COMBINED TAP AND HAND -DRYER
The present invention relates generally to the field of hand drying, and in particular to
arrangements for hand-drying at a sink such as may be provided in a commercial
washroom or the like.
In washrooms, it is common to provide one or more sinks or water basins for washing,
and one or more separate, wall-mounted hand-dryers which users can then use to dry
their hands.
Figure 1 illustrates one type of wall-mounted hand-dryer 1, which is currently marketed
and sold under the model name AB01, as part of the Dyson Airblade® range of hand
dryers. It works by using a motor-driven fan to force air at high pressure through an
opposing pair of narrow, slit-like nozzles 2, 3, each less than 1mm wide. This creates
two opposing thin sheets, or "blades", of high velocity air which act to strip water from
the front and backs of a user's hands as they are 'dipped' - palms open - between the
opposing nozzles 2, 3.
The drying air is fed to the nozzle 3 via a respective air duct 3a which connects to the
pressure side of a motor-driven fan (not shown) located inside the hand dryer 1. The air
duct 3a flattens near the nozzle so that it spans the width of the nozzle 3. Consequently,
air is fed from behind the nozzles 3, with different portions of the nozzle 3 effectively
being fed in parallel, and the air exits the nozzle 3 "straight-on". This is illustrated in
Figure 1.
Air is fed to the rear nozzle 2 in a similar manner via a separate duct (not shown)
corresponding to the duct 3a. The nozzle 2 is scalloped to follow the back of the user's
hands: this deliberate physical shaping of the rear nozzle encourages "turning" of the
airflow as it passes through the nozzle 2, so that air is angled both into the thumb and
forefinger of the user and also back into the little finger of the user, which improves the
overall drying performance. This is also illustrated in Figure 1.
In some washrooms, hand dryers are instead located over the basin of the sink, so that a
user can conveniently dry their hands at the sink - without having to move - and at the
same time water dripping from the hands can collect in the basin of the sink and drain
into the mains drainage system through the existing waste pipe. One such arrangement
is described in US51991 18A.
The present invention is concerned with hand drying at a sink or water basin.
According to the present invention there is provided a fixture for a sink, the fixture
comprising: a water tap incorporating a spout arranged to project over the basin of the
sink, and two hand-dryer nozzles - at least one for each of a user's hands; wherein each
left-hand nozzle is located on the left-hand side of the spout and each right-hand nozzle
is located on the right-hand side of the spout so that the spout acts as a dividing partition
between the left-hand and right-hand nozzles.
The fixture is thus dual-purpose: it incorporates both a water tap for washing a user's
hands and at least one hand-dryer nozzle for drying each of the user's hands.
Advantageously, the configuration of the fixture means also that the water spout itself is
dual-function: it both conveys water for washing and then usefully functions as a
partition between the hand-dryer nozzles to encourage correct usage of the left-hand
nozzle for drying the left hand and the right-hand nozzle simultaneously for drying the
right hand.
In this context, the "left-hand side"/"right-hand side" is the side which, in use, is on the
user's left/right when the user is standing in front of the sink, facing the fixture.
Similarly, the "left hand nozzle'V'right hand nozzle" is the nozzle nominally intended to
be used to dry a user's left/right hand.
The fixture is preferably arranged so that the spout bisects the two nozzles - thus acting
as a central partition between the nozzles - but this is not essential.
In a particular embodiment, there is provided a fixture comprising i) an opposing pair of
said left-hand nozzles arranged on the left side of the spout for directing air onto the
front and back of a user's left hand as it is passed - with open palm - in between the
opposing nozzles, and ii) an opposing pair of said right-hand nozzles arranged on the
right hand side of the spout for directing air onto the front and back of a user's right
hand as it is passed - with open palm - in between the nozzles.
Thus, the nozzles provide an advantageous, "double-sided" hand-drying action.
Positioning the opposing nozzles on the fixture - rather than, for example, the opposing
walls of the sink - allows the separation between opposing nozzles to be optimized.
This is particularly beneficial for high-speed hand dryers (exit airspeed >100m/s),
because subsequent diffusion of the airflow after it exits the nozzles can cause the
airspeed to fall off dramatically over distances of the order of a few cm, so the ability to
optimize the separation between opposing nozzles is critical to achieving good drying
performance.
The left-hand and right-hand nozzles may conveniently be positioned along respective
parts of the fixture which extend laterally away from the spout. Equally, said opposing
pair of left-hand and right-hand nozzles may conveniently be positioned along
respective opposing parts of the fixture which each extend laterally away from the
spout. Positioning the nozzles on a laterally-extending part of the fixture - rather than
directly on the wall of the spout - allows the nozzles to be located at a more natural
width for the user. The laterally-extending parts of the fixture need not extend
perpendicular to the spout.
A plurality of left-hand nozzles (or plurality of opposing pairs of left-hand nozzles) may
be provided, extending along the respective part (or opposing parts) of the fixture.
Similarly, a plurality of right-hand nozzles (or plurality of opposing pairs of right-hand
nozzles) may be provided, extending along the respective part (or opposing parts) of the
fixture. The nozzles may be arranged in one or more rows on the respective part of the
fixture.
Utilising a plurality of nozzles extending laterally along the respective part of the
fixture, the effective width of the drying jet is increased. A similar effect can be
achieved using fewer nozzles - possibly one nozzle - if the nozzle(s) is (are) elongated.
The laterally extending parts of the fixture may each comprise a supply duct, with the
respective nozzle(s) on that part of the fixture extending axially along the wall of the
supply duct so as to extend across the width of the user's hand when it is held - palm
open - in front of the nozzles. Each supply duct is arranged to communicate at its inlet
end - being the end nearer the user's respective thumb in use - with the output side of a
motor-driven fan for driving an axial airflow through the duct, serially to each of the
nozzles.
Thus, air is fed "inside-to-out" axially along the supply duct. Consequently, the nozzle
exit velocity towards the inlet end of the supply duct has a significant axial component,
which tends to angle the airflow into the thumb and forefinger of the user in use, for
effective drying of that area of the user's hand. This is achieved without the
inconvenience and cost of having to use "shaped" nozzles such as the rear 'scalloped'
nozzle in Figure 1.
A large axial component to the nozzle exit velocity may be less preferable away from
the user's thumb, where straighter nozzle exit velocities may instead be preferred for
providing "square-on" drying of the user's hands. This is addressed by controlling the
axial velocity of the airflow along the supply duct so that it decreases along the length
of the supply duct, thus progressively "straightening" the nozzle exit velocities.
The axial velocity is controlled using a suitable cross-sectional profile for the supply
duct. In one embodiment, the supply duct is arranged to have a generally constant crosssectional
area (preferably cylindrical for ease of manufacture, though this is not
essential). In this case, the axial airflow velocity through the supply duct gradually
decreases along the duct due to serial airflow losses through the nozzle(s).
The use of a constant cross-sectional area along the supply duct is not essential,
however, in order to achieve the aforementioned straightening effect. Alternatively, the
cross-sectional area may vary, provided it does so in a manner which nevertheless
ensures such straightening of the nozzle exit velocity via a corresponding progressive
reduction in the axial flow velocity through the supply duct.
For example, the duct may taper along the length of the supply duct. In this sort of
arrangement, serial flow losses through the nozzle(s) will again tend to reduce the axial
flow velocity through the supply duct. If the taper is a reverse taper, so that the cross
sectional area increases with distance from the inlet end of the duct, then the taper will
contribute a further reduction in axial flow velocity along the supply duct, consistent
with the Continuity Principle.
By contrast, a forward taper will in accordance with the same Principle tend to increase
the axial velocity through the supply duct. In this case, a progressive reduction in the
axial nozzle velocity can nevertheless be achieved simply by ensuring that the
aforementioned effect of the taper does not entirely off-set the reduction in flow
velocity due to serial flow losses through the upstream nozzles (or upstream portions of
the nozzle in the case of an elongate slit). Other cross-sectional profiles may likewise be
employed whilst nevertheless ensuring a net reduction in axial velocity along the supply
duct.
The nozzle(s) preferably extends across the full width of the user's hand, for effective
drying across the full hand span of the user.
In one embodiment, the nozzles each span a width in the range of 80mm to 170mm, for
example.
Though not essential, a preferred range of widths for the nozzle(s) is 130-170mm (to be
measured across all of the nozzles collectively in the case of a plurality of nozzles). This
tends to ensure that the nozzle(s) will effectively extend across the majority of user's
hands in use. The precise nozzle width will be a trade-off between, on the one hand, a
compact fixture design and, on the other hand, the usability of the fixture for users with
relatively large hands. Accordingly, the preferred width may vary - for example by
country or according to the specific sink design. However, tests show that a width
specification of 150mm for the nozzle(s) (with a tolerance of ±10mm) generally offers a
good compromise in most cases.
In a particular embodiment, the nozzles are fed by an air duct running through the spout.
Utilizing the spout for running the air duct to the nozzles provides for a compact fixture
design. In this case, the aforementioned supply ducts would communicate with the
motor-driven fan via the air duct running through the spout, and in a particularly simple
configuration the supply ducts may effectively be in the form of laterally-extending
branches of the air duct running through the spout - so that the supply ducts and main
air duct together form a unitary part.
The wall of the supply ducts may - and preferably do - form part of the exterior of the
fixture. This tends to reduce the part count and assembly costs.
The laterally-extending parts of the fixture and the spout may all lie in a substantially
common plane. This helps minimize interference of the fixture with the washing of a
user's hands.
The nozzle(s) may be in the form of an elongate slit, less than 1mm in width, extending
along the respective part of the fixture.
According to another aspect of the present invention, there is provided an arrangement
comprising: a sink in combination with a fixture as described above, the fixture being
fitted to the sink with the spout projecting over the basin of the sink, the hand dryer
nozzles on the fixture being fluidly connected to the pressure side of a motor-driven fan
for forcing airflow through the nozzles to dry a user's hands. The motor-driven fan may
be configured to force airflow through the nozzles at an exit speed which exceeds
lOOm/s, preferably between 150m/s and 250 m/s.
The spout itself may be arranged to project downwardly over the basin of a sink at an
angle between 0 and 15 degrees, making it particularly comfortable to 'dip' the hands -
palms open - between the opposing nozzles, particularly if the laterally-extending parts
of the fixture lie in the same plane as the spout.
Embodiments of the invention will now be described by way of example with reference
to the accompanying drawings, in which:
Figure 1 is a perspective view of a conventional hand dryer;
Figure 2 shows a perspective view of an arrangement comprising a fixture fitted to a
sink;
Figure 3 is a front view of the arrangement in Figure 2;
Figure 4 is a section taken along A-A in Figure 3;
Figure 5 is a section taken along C-C in Figure 4;
Figure 6 is a perspective view - partly enlarged - of part of the fixture shown n Figures
2 to 5;
Figure 7 is a view from the front of the fixture illustrated in Figures 2 to 6, illustrating
the fixture in use;
Figure 8 is a plan view corresponding to Figure 6, but additionally illustrating the
nozzle exit velocity profile for one of the supply ducts forming part of the fixture;
Figure 9 is a schematic view of an alternative, tapering supply duct;
Figure 10 is a perspective view of an alternative arrangement comprising a fixture fitted
to a sink;
Figure 11 is a perspective view of an alternative arrangement comprising a fixture
which is wall-mounted above a sink; and
Figure 12 is a perspective view of an alternative arrangement, illustrating ducting of air
along the outside of a spout forming part of the fixture.
Figures 2-5 show various views of an arrangement comprising a conventional sink 1
and a fixture 2.
The sink 1 happens to be a "Belfast-style" sink, but in general the sink may be of any
conventional type.
The fixture 2 is fitted to the sink 1 using a locknut 4 underneath the sink 1 which
engages with an externally threaded, hollow fixing stud 6 to clamp the fixture 2 in place
(the fixture 2 may alternatively be fitted adjacent the sink rather than to the sink itself,
according to the style of sink).
The fixture 2 comprises a water tap having a main body 8 which sits adjacent the basin
of the sink 1 and a spout 10 which projects from the main body 8 out over the basin of
the sink 1.
On demand, water for washing is supplied from a main supply line via a water supply
pipe 12, which runs inside the main body 8 and the spout 10 to a downwardly-facing
outlet 10a provided at the fore-end of the spout 10.
The water tap is configured for "hands-free" operation using a conventional sensor and
control loop, which automatically opens a stop valve in the supply line in response to
detection of a user's hands in a washing position. Alternatively, the water tap may be
configured for manual operation.
The fixture 2 also incorporates a hand dryer, which utilizes the inside of the main body
8 and spout 10 as an air duct 11, feeding a plurality of hand-dryer nozzles provided on
the fixture 2.
The hand-dryer nozzles are arranged in two groups: a plurality of left-hand drying
nozzles 14, which are intended in use for drying the user's left hand, and a plurality of
right hand nozzles 16, which are intended in use for drying a user's right hand. The
nozzles 14, 16 have been omitted from Figure 2 for clarity purposes, but are shown in
Figure 6.
The left-hand nozzles 14 are provided on the left-hand side of the spout 10. The righthand
nozzles 16 are provided on the right-hand side of the spout 10.
The left-hand nozzles 14 are arranged in opposing pairs along respective laterallyextending
(in this case perpendicularly-extending) supply ducts 11a, 1lb, which
essentially form integral branches of the air duct 11. Similarly, the right-hand nozzles
16 are arranged in opposing pairs which are positioned along respective laterallyextending
(in this case perpendicularly-extending) supply ducts 11c, l id, which
likewise form branches of the air duct 11.
The nozzles 14, 16 are arranged in two rows along each respective supply duct 1la-d.
Figure 6 shows the specific pattern of nozzles 16 on the respective supply duct 11c,
with the nozzles in one row 26 being laterally offset relative to the nozzles in the
adjacent row 28. The nozzles 16 on the opposing branch 1lb of the air duct 11 are
laterally offset in the opposite sense, indicated by the dotted lines in Figure 6, so that the
pairs of opposing nozzles are not positioned directly opposite one another. This helps to
reduce noise in use by preventing collision between the opposing air jets exiting the
nozzles 16. The left-hand nozzles 14 are arranged in similar fashion on the respective
branches 11a, l lb of the air duct 11.
The air duct 11 is connected to the positive pressure (output) side of a motor-driven fan
unit 30 via a flexible hose 32 which fluidly connects to the inside of the main body 8 via
the hollow fixing stud 6 (if the water supply pipe 12 runs through the fixing stud 6 -
effectively within the air supply line - then adequate provision will need to be made to
route the pipe 12 to the exterior of the air supply line, for connection to the water supply
line). On demand, air is forced by the fan 30 through the air duct 11 and out through
each of the nozzles 14, 16.
The hand dryer is configured for "hands-free" operation using a conventional sensor
and control loop, which automatically switches on the fan unit 30 in response to
detection of a user's hands in a drying position (which should be distinguishable from
the aforementioned washing position - which automatically activates the water tap).
Alternatively, the hand dryer may be configured for manual operation.
In use, a user can perform both washing and hand-drying operations at the sink 1.
To commence the washing operation, the user places his (or her) hands underneath the
outlet 10a as if to wash his hands, and the sensor and control loop operates to deliver
water through the outlet 10a. The user can then proceed to wash his hands in
conventional manner over the basin of the sink 1.
To commence the hand-drying operation, a user dips his wet left-hand - palm open -
between the opposing pairs of nozzles 14 on the left-hand side of the spout 10 and, at
the same time, dips his wet right-hand - palm open - between the opposing pairs of
nozzles 16 on the right hand of the spout 10. The sensor and control loop then operates
to activate the fan 30, which forces air under high pressure through the opposing
nozzles 14, 16: directing high-momentum airflow onto the front and backs of the user's
hands, respectively. To dry his hands, the user then makes one or more generally
'vertical' passes between the slots - palms held open - and the high momentum airflow
strips water from the surface of the user's hands. The general dipping action of the left
hand 34 and right hand 36 is illustrated in Figure 7 (here, looking axially along the
spout 10 from the front), which also illustrates how the spout 10 functions as a central
dividing partition between the hands 34, 36, encouraging correct usage.
The lateral branch ducts 1la-d lie in generally the same plane as the spout 10, which
extends downwardly towards the user at an angle Q(Figure 4) in the range 5 to 15
degrees, preferably 10 degrees. Thus, rather than the user having to dip his hands
vertically between opposing nozzles, the hand entry-angle is tilted towards the user to
make the dipping action more comfortable.
The waste water driven from the hands is conveniently collected in the basin of the sink
1, where it may drain to the mains through the conventional plumbing system for the
sink 1.
Figure 8 - here, looking down on the fixture 2 from above - shows the nozzle exit
velocity profile along the supply duct 11c (which is also illustrative of the exit velocity
profile for the remaining supply ducts 1la, 1lb, l id).
The exit velocity profile is characterised by a significant axial component to the nozzle
exit velocity Ui nearer the inlet end 12 of the supply duct 11c, due to the high axial duct
velocity Vi. This helps to angle the airflow into the thumb and forefinger for effective
drying of this area of the hand.
Away from the inlet end of the branch ducts 11c, there is a progressive decrease in the
axial duct velocity due to a combination of serial flow losses through upstream nozzles
and the uniform cross-sectional area of the duct 11c. Consequently, there is a
progressive straightening of the nozzle exit velocity along the length of the branch ducts
(the intermediate nozzle exit velocities are illustrated only schematically in Figure 8).
So for example, near the very end of the branch ducts 11c, the axial duct velocity V2 is
relatively small and the exit velocity U2 is relatively straight.
The progressive straightening of exit velocities along the length of the branch ducts 11ad
helps maintain a more neutral "square-on" drying characteristic away from the thumb
and forefinger.
The use of a supply duct having a uniform cross-sectional area is not essential to
provide the straightening effect shown in Figure 8, though use of a cylindrical supply
duct may be preferable for ease of manufacture. For example, Figure 9 illustrates use of
a tapered duct, l ie. Here the taper actually off-sets the reduction in axial velocity
caused by serial flow losses through the nozzles 16 - so the straightening effect is not as
pronounced - but a straightening effect is nevertheless achieved by ensuring that the
taper angle is sufficiently shallow that there is still a net reduction in axial velocity
along the duct: in other words, serial flow losses through the nozzles 16 remain the
dominant factor in determining the axial velocity V2.
The use of opposing pairs of nozzles is not essential. Figure 10 shows a "single-sided"
arrangement in which the fixture 200 has a row of left-hand nozzles 140 on the lefthand
side of the spout 100 and a row of right-hand nozzles 160 on the right-hand side of
the spout 100. The nozzles 140, 160 - which in this case are single rows of circular
nozzles - are arranged along respective laterally-extending branch ducts 110a and 110b:
one provided for each set of nozzles 140, 160.
The spout 100 projects forward of the two branch ducts 110a and 110b, so as to act as a
central dividing partition between the left-hand nozzles 140 and the right-hand nozzles
160. The lateral branch ducts are again arranged in the same plane as the spout 100,
which is likewise angled downwardly towards the user at an angle of 10 degrees to
provide user comfort during use.
The fundamental hand drying action is similar to the "double-sided" arrangement of
Figure 2 : the user dips his left hand - palm-open - in front of the left-hand nozzles 140
and at the same time dips his right hand - palm-open - in front of the right-hand nozzles
160. However, because the nozzles 140, 160 only direct air onto one side of the user's
hands, the user must then flip over his hands and repeat the same process for the reverse
side of the hands.
Figure 11 shows a wall-mounted arrangement, in which a fixture 2000 is mounted to the
wall behind the sink 1. The fixture 2000 is configured to provide "double-sided"
drying, via an opposing pair of left-hand nozzles 1400: in this case a pair of elongate
slits which in use span the width of a user's hand, and an opposing pair of right hand
nozzles 1600: likewise taking the form of a pair of elongate slits.
The left-hand nozzles 1400 are provided on the left-hand side of the spout 1000,
whereas the right-hand nozzles 1600 are provided on the right-hand side of the spout
1000. The spout 1000 thus acts as a central dividing partition between the nozzles 1400,
1600.
The fixture 2000 may be fitted to the wall using conventional wall fixings.
The main air supply duct for the nozzles does not have to run through the spout: for
example, in the arrangement in Figure 2, separate air ducts may instead be provided
which run in side-by-side relation with the spout 10. This is illustrated in Figure 12
(only one air duct, 1If, is visible). The spout 10 nevertheless acts as a dividing partition
between the left-hand and right-hand nozzles.
CLAIMS
1. A fixture for a sink, the fixture incorporating a water tap and a hand dryer,
the water tap comprising a spout arranged to project over the basin of the
sink, and the hand dryer comprising two or more hand-dryer nozzles - at
least one for each of a user's hands; wherein each left-hand nozzle is located
on the left-hand side of the spout and each right-hand nozzle is located on
the right-hand side of the spout such that the spout acts as a dividing
partition between the left-hand and right-hand nozzles.
2. A fixture according to claim 1, wherein the left-hand and right-hand nozzles
are positioned on respective parts of the fixture which extend laterally away
from the spout.
3. A fixture according to claim 2, comprising a plurality of said left-hand and
right-hand nozzles extending laterally along said respective parts of the
fixture.
4. A fixture according to claim 1, comprising:
i) an opposing pair of said left-hand nozzles arranged on the left side of the
spout for directing air onto the front and back of a user's left hand as it is
passed - with open palm - in between the opposing nozzles, and
ii) an opposing pair of said right-hand nozzles arranged on the right hand
side of the spout for directing air onto the front and back of a user's right
hand as it is passed - with open palm - in between the nozzles.
5. A fixture according to claim 4, wherein the opposing left hand and right
hand nozzles are positioned on respective opposing parts of the fixture which
extend laterally away from the spout.
A fixture according to claim 5, comprising a plurality of said opposing lefthand
nozzles extending laterally along said respective opposing parts of the
fixture and a plurality of said opposing right hand nozzles extending along
said respective opposing parts of the fixture.
A fixture according to any of claims 2 to 6, wherein the nozzles are arranged
in one or more rows along the respective part of the fixture.
A fixture according to any of claims 2 to 7, wherein said laterally extending
parts of the fixture each comprise a supply duct, the respective nozzle(s) on
that part of the fixture extending axially along the wall of the supply duct so
as to extend across the width of the user's hand when it is held - palm open
- in front of the nozzles, each supply duct communicating at its inlet end -
being the end nearer the user's respective thumb in use - with a motordriven
fan for driving an axial airflow through the duct, serially to each of
the nozzles.
A fixture according to any of claims 8, wherein the supply ducts each
communicate with the motor-driven fan via an air duct running through the
spout.
A fixture according to claim 9, wherein the supply ducts are laterallyextending
branches of said air duct running through the spout.
11. A fixture according to any of claims 2 to 10, wherein said parts of the
fixture and the spout all lie in a common plane.
12. A fixture according to any of claims 2 to 11, wherein each nozzle is in the
form of an elongate slit, less than 1mm in width, extending along the
respective part of the fixture.
13. An arrangement comprising: a sink in combination with a fixture according
to any preceding claim, the fixture being fitted with the spout projecting
over the basin of the sink, the hand dryer nozzles on the fixture being fiuidly
connected to the pressure side of a motor-driven fan for forcing airflow
through the nozzles to dry a user's hands.
14. An arrangement according to claim 13, wherein the motor-driven fan is
configured to force airflow through the nozzles at an exit speed which
exceeds lOOm/s.
15. An arrangement according to claim 13or 14, wherein the spout extends
downwardly at angle between 5 and 15 degrees.