Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Dryiniz Apparatus
The invention relates to drying apparatus which inalces use of a narrow jet of
high
velocity, high pressure air to dry an object, including part of the human
body.
Particularly, but not exclusively, the invention relates to a hand dryer in
which the air jet
is emitted through a slot-like opening in the casing of the hand dryer.
The use of air jets to dry hands is well lcnown. Examples of hand dryers which
emit at
least one air jet through a slot-like opening are shown in GB 2249026A, JP
2002-
034835A and JP 2002-306370A. However, in practice it is very difficult to
achieve an
evenly distributed airflow of sufficiently high momentum to dry the user's
hands
efficiently in an acceptably short length of time. The prior ai-t does not
achieve this.
It is an object of the invention to provide drying apparatus which, in use,
emits an air jet
through a slot-like opening which is capable of drying an object in a short
time as
compared to the prior art. It is another object to provide a hand dryer which
is capable
of drying the user's hands in a short time in comparison to the prior art. It
is a further
object of the invention to provide an improved hand dryer in which the drying
efficiency is iinproved in comparison to the prior art.
The invention provides drying apparatus having a casing, a cavity formed in
the casing
for receiving an object, a fan located in the casing and capable of creating
an airflow,
and at least one slot-like opening communicating with the fan and arranged in
the casing
so as to direct an airflow transversely across the cavity, wherein the slot-
like opening
has a maximum width which is no greater than 1.0 mm.
By providing a slot-like opening having a width of no more than 1.0mm, the
momentum
of the airflow emitted through the opening is greatly increased in comparison
to that of
the prior art devices. This increases the efficiency of the dryer by virtue of
the fact that
more water is blown from the object during each pass thereof through the
airflow
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exiting the slot-like openings. The distribution of the airflow along the slot-
like
openings is also comparatively even when compared to the prior art.
In one preferred embodiment, the slot-like opening has a constant width, more
preferably a width of at least 0.3mm and advantageously no more than 0.4mm.
These
preferred dimensions provide the airflow with a particularly effective level
of
momentum.
In a preferred embodiment, a hand dryer has two opposed slot-like openings,
one in the
front wall of the cavity and one in the rear wall. Preferably, the width of
the slot-like
opening in the front wall of the cavity is smaller than the width of the slot-
like opening
in the rear wall of the cavity. This arrangement allows a greater proportion
of the
airflow to be emitted onto the baclcs of the user's hands which enhances the
drying
process.
In a further preferred embodiment, the slot-like opening has a width which
varies along
its length, with the maximum width being greatest at the centre of the slot-
like opening.
The maximum width of the slot-like opening is preferably no more than twice
the
minimum width. This provides an arrangement in which a larger mass of air is
emitted
from the centre of the slot-like opening which is advantageous when the slot-
like
openings are provided in a hand dryer.
Embodiments of the invention, both in the form of a hand dryer, will now be
described
with reference to the accompanying drawings, in which:
Figure 1 is a side view of a hand dryer according to a first embodiment of the
invention;
Figure 2 is a perspective view of the hand dryer of Figure 1;
Figure 3 is a side sectional view of the hand dryer of Figure 1;
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Figure 4 is a side sectional view, shown on an enlarged scale, of the upper
ends of the
air ducts forming part of the hand dryer of Figure 1;
Figure 5 is a schematic sectional side view, shown on a further enlarged
scale, of the
slot-like opening located in the front wall of the cavity of the hand dryer of
Figure 1;
Figure 6 is a scheinatic sectional side view, shown on the same further
enlarged scale,
of the slot-like opening located in the rear wall of the cavity of the hand
dryer of Figure
1; and
Figure 7 is a schematic front view of the rear slot-like opening forming part
of a hand
dryer according to a second embodiment of the invention.
Referring firstly to Figures 1 and 2, the hand dryer 10 shown in Figures 1 to
6
coinprises an outer casing 12 having a front wall 14, a rear wall 16, an upper
face 18
and side walls 20, 22. The rear wall 16 can incorporate fixing devices (not
shown) for
securing the hand dryer 10 to a wall or other structure prior to use. An
electrical
connection (not shown) is also provided on the rear wall or elsewhere on the
casing 12.
A cavity 30 is formed in the upper part of the casing 12 as can be seen from
Figures 1
and 2. The cavity 30 is open at its upper end and delimited thereat by the top
of the
front wall 14 and the front of the upper face 18. The space between the top of
the front
wall 14 and the front of the upper face 18 forms a cavity entrance 32 which is
sufficiently wide to allow a user's hands to be introduced to the cavity 30
through the
cavity entrance 32. The cavity 30 is also open to the sides of the hand dryer
10 by
appropriate shaping of the side walls 20, 22.
The cavity 30 has a front wall 34 and a rear wall 36 which delimit the cavity
30 to the
front and rear respectively. Located in the lowermost end of the cavity 30 is
a drain 38
which communicates with a reservoir (not shown) located in the lower part of
the casing
12. The purpose of the drain and reservoir will be described below.
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As shown in Figure 3, a fan 40, which is driven by a motor (not shown), is
located
inside the casing 12. The motor is connected to the electrical connection and
is
controlled by a controller 41. The inlet 42 of the fan 40 communicates with an
air inlet
44 formed in the casing 12. A filter 46 is located in the air passageway
connecting the
air inlet 44 to the fan inlet 42 so as to prevent the ingress of any debris
which might
cause damage to the motor or the fan 40. The outlet of the fan 40 communicates
with a
pair of air ducts 50, 52 which are located inside the casing 12. The front air
duct 50 is
located primarily between the front wall 14 of the casing 12 and the front
wal134 of the
cavity 30, and the rear air duct 52 is located primarily between the rear wall
16 of the
casing 12 and the rear wall 36 of the cavity 30.
The air ducts 50, 52 are arranged to conduct air from the fan 40 to a pair of
opposed
slot-like openings 60, 62 which are located in the front and rear walls 34, 36
respectively of the cavity 30. The slot-like openings 60, 62 are arranged at
the upper
end of the cavity 30 in the vicinity of the cavity entrance 32. The slot-like
openings 60,
62 are each configured so as to direct an airflow generally across the__cavity
entrance 32
towards the opposite wall of the cavity 30. The slot-like openings 60, 62 are
offset in
the vertical direction and angled towards the lowermost end of the cavity 30.
The air ducts 50, 52 are arranged -to conduct air from the fan 40 to a pair of
opposed
slot-like openings 60, 62 which are located in the front and rear walls 34, 36
respectively of the cavity 30. The slot-like openings 60, 62 are arranged at
the upper
end of the cavity 30 in the vicinity of the cavity entrance 32. The slot-like
openings 60,
62 are each configured so as to direct an airflow generally across the cavity
entrance 32
towards the opposite wall of the cavity 30. The slot-like openings 60, 62 are
offset in
the vertical direction and angled towards the lowermost end of the cavity 30.
Figure 4 shows the upper ends of the air ducts 50, 52 and the slot-like
openings 60, 62
in greater detail. As can be seen, the walls 54a, 54b of the air duct 50
converge to form
the slot-like opening 60 and the walls 56a, 56b of the air duct 52 converge to
form the
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slot-like opening 62. Even greater detail can be seen in Figures 5 and 6.
Figure 5
shows that the slot-like opening 60 has a width of Wl and Figure 6 shows that
the slot-
like opening 62 has a width of W2. The width Wl of the slot-like opening 60 is
smaller
than the width W2 of the slot-like opening 62. The width W1 is 0.3mm and the
width
5 W2 is 0.4mm. In this einbodiinent, both widths W 1 and W2 are constant
across the
length of each respective slot-like opening.
Sensors 64 are positioned in the front and rear walls 34, 36 of the cavity 30
immediately
below the slot-like openings 60, 62. These sensors 64 detect the presence of a
user's
hands which are inserted into the cavity 30 via the cavity entrance 32 and are
arranged
to send a signal to the motor when a user's hands are introduced to the cavity
30. As
can be seen fioin Figures 1 and 3, the walls 54a, 54b, 56a, 56b of the ducts
50, 52
project slightly beyond the surface of the front and rear walls 34, 36 of the
cavity 30.
The inward projection of the walls 54a, 54b, 56a, 56b of the ducts 50, 52
reduces the
tendency of the user's hands to be sucked towards one or other of the walls
34, 36 of the
cavity, which enhances the ease with which the hand dryer 10 can be used. The
positioning of the sensors 64 iinmediately below the inwardly projecting walls
54a, '54b,
56a, 56b of the ducts 50, 52 also reduces the risk of the sensors 64 becoming
dirty and
inoperative.
As can be seen from Figure 2, the shape of the cavity entrance 32 is such that
the front
edge 32a is generally straight and extends laterally across the width of the
hand dryer
10. However, the rear edge 32b has a shape which consists of two curved
portions 33'
which generally follow the shape of the backs of a pair of human hands as they
are
inserted downwardly into the cavity 30 through the cavity entrance 32. The
rear edge
32b of the cavity entrance 32 is substantially symmetrical about the centre
line of the
hand dryer 10. The intention of the shaping and dimensioning of the front and
rear
edges 32a, 32b of the cavity entrance 32 is that, when a user's hands are
inserted into
the cavity 30 through the cavity entrance 32, the distance from any point on
the user's
hands to the nearest slot-like opening is substantially uniform.
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The hand dryer 10 described above operates in the following manner. When a
user's
hands are first inserted into the cavity 30 through the cavity entrance 32,
the sensors 64
detect the presence"of the user's hands and send a signal to the motor to
drive the fan
40. The fan 40 is thus activated and air is drawn into the hand dryer 10 via
the air inlet
44 at a rate of approximately 20 to 40 litres per second and preferably at a
rate of least
25 to 27 litres per second, more preferably air is drawn into the hand dryer
10 at a rate
of 31 to 35 litres per second. The air passes through the filter 46 and along
the fan inlet
42 to the fan 40. The airflow leaving the fan 40 is divided into two separate
airflows;
one passing along the front air duct 50 to the slot-like opening 60 and the
other passing
along the rear air duct 52 to the slot-like opening 62.
The airflow is ejected from the slot-like openings 60, 62 in the form of very
thin,
stratified sheets of high velocity, high pressure air. As the airflows leave
the slot-like
openings 60, 62, the air pressure is at least 15 kPa and preferably
approximately 22 to
23 kPa.
Furthennore, the speed of the airflow leaving the slot-like openings 60, 62 is
at least 80
m/s and preferably at least 100 or 150 m/s, more preferably approximately
180m/s.
Because the size of the slot-like opening 62 located at the end of the rear
duct 52 is
greater than the size of the slot-like opening 60 located at the end of the
front duct 50, a
larger volume of air is emitted from the duct 52 than from the duct 50. This
provides a
greater mass of air for drying the backs of the user's hands which is
advantageous.
The two thin sheets of stratified, high velocity, high pressure air are
directed towards the
surfaces of the user's hands wliich, during use, are inserted fully into the
cavity 30 and
are subsequently withdrawn from the cavity 30 via the cavity entrance 32. As
the user's
hands pass into and out of the cavity 30, the sheets of air blow any existing
water off the
user's hands. This is achieved reliably and effectively because of the high
momentum
of the air leaving the slot-like openings 60, 62 and because the airflow is
evenly
distributed along the length of each slot-like opening 60, 62.
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Each stratified sheet of air is directed towards the wall of the cavity 30
which is remote
from the slot-like opening througll which the respective sheet of air is
emitted. Because
the slot-like openings 60, 62 are also- inclined towards the lowermost end of
the cavity
30, the emitted airflows are directed into the cavity 30. This reduces the
risk of
turbulent air movement being felt by the user outside the casing, eg in the
user's face.
It is envisaged that it will take only a small nuinber of "passes" of the hand
dryer
described above to dry a user's hands to a satisfactory degree. (By "pass", we
mean a
single insertion of the hands into the cavity and subsequent removal therefrom
at a
speed which is not unacceptable to an average user. We envisage that a single
pass will
have a duration of no more than 3 seconds.) The momentum achieved by the
airflows is
sufficient to remove the majority of water found on the surface of the user's
hands after
washing during a single pass.
The water removed by the airflows is collected inside the cavity 30. Each
airflow will
rapidly lose its momentum once it has passed the user's hands and the water
droplets
will fall to the lower end of the cavity 30 under the forces of gravity whilst
the air exits
the cavity 30 either through the cavity entrance 32 or via the open sides of
the cavity 30.
The water, however, is collected by the drain 38 and passed to a reservoir
(not shown)
where it is collected for disposal. The reservoir can be emptied manually if
desired.
Alternatively, the hand dryer 10 can incorporate some form of water dispersal
system
including, for example, a heater for evaporating the collected water into the
atinosphere.
The means by which the collected water is dispersed does not form part of the
present
invention.
The second embodiment of the invention is identical to the embodiment
described
above in all respects save that of the width of the slot-like opening 62
located at the end
of the rear duct 52. Whereas the width W2 of the slot-like opening 62 is
constant in the
first embodiment, it is not constant in the second embodiment. A front view of
the slot-
like opeiung (shown schematically for clarity) is shown in Figure 7.
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In this second embodiment, the lower edge 62a of the slot-like opening 62 is
straight, as
it is in the first einbodiment. However, the upper edge 62b of the slot-like
opening 62 is
curved in the central area 1 thereof so that the widtll of the slot-like
opening 62 increases
fiom a minimum width w to a maximum width W. Outside the central area 1, the
minimum width w of the slot-like opening 62 is constant aiid the preferred
value of the
ininiinuin width w is 0.4mm. The preferred value of the maximum width W is
less than
twice the value of the minimum width w, in this case 0.7mm.
In this embodiment, the central area 1 covers substantially one half of the
entire length L
of the slot-like opening 62. The distance between the upper edge 62b and the
lower
edge 62a begins to increase at a point approximately one quarter of the way
along the
slot-like opening 62 from either end thereof. The shape of the upper edge 62b
is
syminetrical and takes the form of a smooth curve having its highest point in
the centre
of the slot-like opening.
In use, the hand dryer according to the second embodiment is capable of
emitting an
increased mass of air through the centre of the rear slot-like opening 62 in
comparison
to the first embodiment. This is advantageous because the area of the hands
which is
often most difficult to dry using this type of hand dryer is that around the
thumbs and
forefingers. The emission of an increased mass of air in that region of the
hands
improves the ability of the dryer to dry the hands evenly.
It will be appreciated that, in this second embodiment, the width of the rear
slot-like
opening 62 can be varied by altering the shape of either or both edges and
that the
precise shape of the slot is not limited to that shown in Figure 7.
In a further alternative embodiment, the slot-like openings 60, 62 can be
arranged so
that the sheets of air which are emitted therefrom are directed generally
along planes
which are substantially parallel to one another. This minimises the amount of
turbulent
flow present inside the cavity 30 whilst the drying apparatus is in use.
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The invention is not intended to be limited to the precise detail of the
einbodimeiit
described above. Modifications and variations to the detail which do not alter
the scope
of the iuZvention will be apparent to a skilled reader. For example, the shape
of the
cavity 30 and its entrance 32 may be altered without departing from the
essence of the
present invention.
