Note: Descriptions are shown in the official language in which they were submitted.
CA 02310472 2000-08-09
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AUTOMATIC URINAL FLUSHING SYSTEM
Field of the invention
The present invention relates to an automatic urinal flushing system.
Bacl~round of the invention
Historically, urinals were flushed in the same way as toilet pans. That is, a
cistern was provided and a mechanical actuator was used to actuate the cistern
when a
user had finished at the urinal. Since urinals are universally installed in
public
~ o conveniences, places of work, and places frequented by the general public
such as
hotels and clubs, rather than in the home, urinals are used by members of the
general
public who feel no special obligation towards the premises and the maintenance
of
cleanliness in those premises. Therefore the regular operation of user
actuated flushing
cisterns could not be guaranteed with the usual result of a strong smell of
dried urine.
~ 5 In the last decade or so in order to overcome such problems automatic
systems
for the flushing of urinals have been installed and these have provided many
advantages. Included amongst the advantages are the elimination of the problem
of
smell and, particularly since the advent of AIDS, an increased perception of
hygiene
since all users do not have to come into contact with a mechanical flushing
actuator. In
zo the simplest form these automatic flushing urinals operated on a time basis
and flushed
at regular time intervals irrespective of actual use. This therefore wasted
substantial
amounts of water. In order to overcome this problem it has been known to
install a
remote sensing system which is intended to detect the presence of a user at
the urinal
and thereby limit the times of flushing to times immediately after the
detection of a
z5 user.
Such relatively sophisticated systems suffer from a number of problems.
These include the cost of a solenoid valve which controls the flushing
operation. The
power requirements of the solenoid valve which must be held open for the
duration of
the flush, dictate that the power be supplied by a 240 volt AC mains supply.
This
3o applies whether the valve is 240 volt AC or whether it is 12 volt DC (in
which case an
expensive transformer (and rectifier) are required). This therefore
necessitates the
provision of two separate trades (plumbers and electricians) at the
installation,
especially on new building sites where trade demarcations are more rigidly
enforced.
Also the concerns of management about safety are heightened since there is a
fear of
s5 use of 240 volt AC power in conjunction with water and metal pipes as
potentially
constituting a safety hazard. All these factors contribute substantially to
the cost of
installation, the cost of maintenance of such systems, and the reluctance to
install same.
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It is the object of the present invention to provide an automatic urinal
flushing
system which has both a low manufactured cost and a low installation cost.
Summar3r of the invention
According to the present invention, there is disclosed an automatic urinal
flushing system for flushing one or more urinals installed together in a
gentlemen's
toilet, said system comprising:
a cistern having a flush pipe connected to said urinal(s), an inlet pipe
connected to a mains water supply, a float operated inlet valve connected to
said inlet
~ o pipe to set the maximum level of water within the cistern, and a flush
valve connected
to said flush pipe and operable by a mechanically actuated mechanism;
an ultrasonic distance sensor mountable adjacent said urinal to detect the
presence of a urinal user within a predetermined range;
an electrically operable mechanical actuator mountable adjacent said cistern
to
~ 5 actuate said mechanism; and
an electronic control circuit receiving an input from said sensor, providing
an
output signal to said electrically operable mechanical actuator, and having a
stored
control program whereby in response to one or more inputs from said sensor the
time
of said output signal is determined in accordance with said stored control
program.
zo
Brief description of the drawing
An embodiment of the present invention will now be described with reference
to the accompanying drawings in which:
Fig. 1 is a perspective view of a prior art urinal installation;
z5 Fig. 2 is a similar view of another prior art urinal installation;
Fig. 3 is a schematic representation of the automatic urinal flushing system
of
the preferred embodiment; and
Fig. 4 is a schematic side elevation of the installation of the arrangement of
Fig. 3.
Detailed description of the preferred embodiment
Fig. 1 shows a prior art urinal installation in which a gentlemen's bathroom 1
is provided with three individual stall urinals 2 each of which is supplied
with flushing
water via concealed piping 4. The piping 4 is directly connected to a mains
water
supply 5 via a solenoid valve 6 which is connected directly to the 240 volt AC
mains 7.
Each of the urinals 2 is provided with a corresponding infrared sensor 8 which
is commonly mounted at chest height, or similar, and generally central
relative to each
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urinal. Each sensor 8 is connected by concealed wiring 9 to a control unit 10
which is
in turn connected to the solenoid valve 6.
Traditional practice is for a maximum of three single stall urinals 2 to be
supplied by a single solenoid valve 6. Therefore if more than three urinals 2
are
provided in a given installation, it is necessary to have more than one
solenoid valve 6
and its associated equipment.
The above described prior art arrangement suffers from the disadvantage that
the three single stalls are supplied by the one valve 6 in order to reduce
installation
costs. But this increases water usage since all three stalls are flushed even
if only one
~ o is used. Since one stall has a required flush volume of approximately 2
litres,
significant amounts of water can be wasted.
Fig. 2 shows another prior art urinal installation in which like items to
those
shown in Fig. 1 are allocated like designation numbers. In Fig. 2, a bathroom
30 is
provided with three slab urinals 32 each of which has a spreader pipe 33 that
is
~ s individually supplied with flushing water via a corresponding cistern 31.
The flush is
controlled by a solenoid valve 36 which is schematically illustrated as being
in the flush
pipe connected between the cistern 31 and spreader pipe 33.
One advantage of the cistern 31 is that the solenoid valve 36 need not be so
expensive as to include a flow reversal protection valve since the mains
supply is
2o protected by the inlet valve (not illustrated but conventional) of the
cistern 31.
The slab urinals 32 require a flushing volume of approximately 2 litres for
each 600mm of urinal length. There is also a problem in using the valve 6 or
36 to
control the flush volume since in fact the valve time of opening does not
directly
control the volume. Instead the volume is determined in large part by the
constriction
25 to flow presented by the pipework 4 including the spreader pipes 33. Thus
in general it
is necessary for each valve 6, 36 to be set up to open for a different time
(generally in
the range of 5-10 seconds) for each installation.
Further problems with the above prior art installations are as follows.
Firstly, the infrared sensors 8, being directly located in full view of the
user of
3o the urinal, represent a tempting target for vandalism. Such sensors 8 are
commonly
blocked by chewing gum and like substances which thereby easily renders them
inoperative. In addition, the bathrooms 1, 30 in modern times are supplied
with hot air
dryers 12 and the heat generated by the use of such dryers often results in
false
triggering of the infrared sensors 8.
as The solenoid valve 6, 36 (and its mounting bracket) is itself relatively
expensive, typically having a purchase price of approximately $80. Either it,
or its
supply transformer, is generally directly wired into the 240 volt AC mains
supply of the
building. Therefore the wiring of the solenoid valve 6, 36 requires the
presence of an
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electrical tradesmen on site at substantially the same time as the other
installation is
completed by a plumber.
In addition, the infrared sensors 8 are susceptible to being triggered by
persons
walking by, for example walking through the doorway adjacent the hot air.dryer
12 and
s passing directly to stalls (not illustrated) containing lavatory pans. In
attempts to
prevent such false triggering, the sensors 8 are provided with a lens
arrangement which
enables the beam direction ete to be set, thereby increasing the cost and
installation
complexity of the overall system.
It is also known to overcome the problem of false triggering by infrared
~ o sensors 8 by using microwave devices, however these are much more
expensive and
therefore again increase the cost of the installation.
Fig. 3 shows a preferred embodiment of the automatic urinal flushing system
according to the invention. The system includes a substantially conventional
cistern 14
having a flush pipe 15 connected to the concealed piping 4 as before. The
cistern 14
also includes a substantially conventional flush valve 16, which is actuated
mechanically by lifting to operate the flushing action, and an inlet pipe 17
having a
conventional float operated inlet valve 18 which determines the height of
water within
the cistern 14. The inlet pipe 17 is supplied from the mains water supply 5.
The
preferred form of cistern and actuating mechanism are those described in
Australian
Zo Patents Nos 673,959 and 673,292.
Located immediately above the cistern 14 is an electrically operated actuator
19 which in its preferred form is a door lock actuator from an automobile. As
a
consequence it operates at 12 Volts DC and is of low manufactured cost and
high
reliability. The electric actuator 19 is positioned immediately above the
flush valve 16
2s and is operable on supply of a pulse of energy (typically 2A or less for a
duration of
SOOmSec or less) which therefore momentarily lifts the flush valve 16.
Thereafter the
flushing water maintains the flush valve 16 in its raised position until the
water has
substantially drained from the cistern 14. As a consequence of this
arrangement, the
electrical energy consumed to initiate the t7ush is low and the electrical
energy
so consumed to maintain the flush for the desired duration of the flush is
nil.
Preferably, the electric actuator 19 takes the form of a small DC electric
motor, a gearbox and a rack and pinion mechanism. The moving rack initiates
the
flushing action. Preferably the rack moves against a spring which provides a
restoring
force. Alternatively, the cost of the spring can be avoided and a reverse
polarity pulse
3s applied to the motor to re-set the actuator 19.
The electric actuator 19 is connected to, and controlled by, a control unit 20
to
which is connected one or more ultrasonic sensors 28. Again the ultrasonic
sensors 28
are known from automotive applications where they are used as range finders at
the
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rear of vehicles such as trucks which are intended to reverse into a loading
bay. As
with the actuator 19, the sensors 28 have a low manufactured cost and high
reliability.
The sensors 28 are used to provide the driver of the vehicle with an
indication as to the
distance between the moving vehicle and the stationary loading bay. As-
indicated in
s Fig. 3, the ultrasonic sensor 28 operates by sending out one or more
ultrasonic
outgoing pulses 21 which are then reelected from an object so as to create an
incoming
echo pulse 22.
The control unit 20 is supplied with low current (eg 500 mA or less) from a
low cost encapsulated battery recharging pack 23 which is simply plugged into
an
i o existing 240 volt AC power point 24 by the plumber. Therefore no
electrician is
required on site at the time of installation. Because of the low power to the
electric
actuator 19, the low cost encapsulated battery recharging pack 23 is able to
be utilised
as the supply of electric energy.
Alternatively, as indicated by dotted lines in Fig. 2, the control unit 20 can
be
i 5 supplied with energy from a solar cell 25 which derives its energy from
the lighting
provided within the bathroom 1. In the event that a solar cell 25 is used, the
control
unit 20 is provided with a small storage battery (not illustrated) to provide
sufficient
energy for a flush and is recharged by the solar cell 25 between flushes.
As indicated in Fig. 4, the ultrasonic sensors 28 are preferably located at
zo approximately ankle height immediately below each individual urinal 2.
The overall arrangement provides a number of advantages.
Firstly, the sensors 28 are very difficult to see and therefore are not
expected
to come to the notice of vandals.
Secondly, the cistern 14 is able to have its internal level set at either 2, 4
or 6
z5 litres flush volume. As a result each individual urinal 2 can have a
corresponding
cistern 14 (and because of the low overall cost of the arrangement this
becomes feasible
from an installation cost, it certainly being the most economical in terms of
water
usage). Or each pair of urinals 2 can share a cistern 14. The other
possibility is for
the one cistern 8 to supply three individual urinals 2. This is indicated in
Fig. 4 by the
so three different water heights illustrated within the cistern 14.
In addition, the control unit 20 can be arranged so that any detection of a
person for a period less than, say, 10 seconds is not regarded as a positive
detection of
a person using a urinal. This in large part overcomes the problem of false
triggering.
Thus the control unit 20 is not inadvertently triggered by persons walking
past the
ss urinal but not using them. Further, the ultrasonic sensors 28, being
independent of any
heat, are not falsely triggered by heat sources other than humans, such as a
hot air
dryer 12. An alternative arrangement, not illustrated, is to mount the sensors
28 in the
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ceiling and direct same downwardly towards the step (or similar) on which the
user
stands to urinate.
The above described arrangement provides a number of very substantial
advantages. Firstly, the manufactured cost of the components of the system is
very low
s since pre-existing units such as the battery recharging pack 23, the
electric actuator 19
and the ultrasonic sensors) 28 are able to be used, the cistern 14 is a high
volume
production article of low cost, and the expensive solenoid valve 6 is avoided.
As a
consequence the manufactured cost of the embodiment illustrated in Fig. 2
(excluding
the solar cell 25) is very substantially reduced compared with the
manufactured cost of
~o the solenoid valve arrangements illustrated in Figs. 1 and 2.
Further, on installation, only a plumber is required and therefore only a
single
trade is required to be supplied and coordinated, compared with two in the
prior art.
Thirdly, the incidence of vandalism is expected to be much less since the
ultrasonic sensors 28 are quite unobtrusive and are not thought to present a
target to
i 5 vandals.
The foregoing describes only one embodiment of the present invention and
modifications, obvious to those skilled in the art, can be made thereto
without departing
from the scope of the present invention.
