Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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~ FLUSEING MECHANISM AND METHOD OF REDUCING THE FLUSHING
VOLUME OF A CISTERN
This invention relates to flushing mechanism including a
forcing means which clo6es an outlet valve when the water
level reaches a predetermined lower level.
~s pressure to conserve water mounts, authorities
around the world are regulating to decrease the maximum
volume of water which may be flushed from a toilet cistern
during a full flush. To date, lower flushing volumes have
been obtained simply by filling a toilet cistern to a lower
level, so that the volume discharged is less than that
previously discharged. This, however, has the drawback
that there is a lesser head of water to flush the exiting
water into a toilet bowl.
It is an object of the present invention to provide a
flushing mechanism which overcomes or at least minimises
the problems of the prior art, or at least provides the
public with a useful choice.
Further objects of the invention will become apparent
from the following description.
According to one aspect of the present invention there
is provided a flushing mechani~m for reducing the volume of
fluid flushed from a toilet cistern during a full flush,
said mechanism including a valve means which may be opened
by raising a 10at of the valve means and closed by
applying downward force to said float, said mechanism being
provided with forcing means positioned so that, in use,
when the water level in the cistern lowers to a
predetermined level the valve means is closed by the
downward force applied by the forcing means to the float,
closing the valve means prior to the level at which the
valve would close without the ~orcing means.
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According to the invention there i5 also provided a method
of decreasing the volume of fluid flushed from a toilet
cistern during a full flush, said cistern including valve
means which may be opened by raising a float of the valve
means and closed by applying downward force to said float,
said method comprising providing a forcing means which
applies downward force to the float as the water level in
the cistern lowers about the forcing means.
In one embodiment the forcing means consists of a container
which collects water therein and produces downward force on
the outlet val~e as the water level lowers.
According to another embodiment the forcing means is a
bell which, due to the force of suction between the bell
and the water surface, closes the valve as ~he water level
lowers.
Further aspects of this invention, which should be
considered in all its novel aspects, will become apparent
from the following description, given by way of example of
possible embodiments thereof, in which reference is made to
the accompanying drawings in whichs
Fiqure 1: shows the flushing mechanism according to one
possible embodiment.
Figure 2: shows the cup which forms the forcing means in
the embodiment shown in Figure 1.
Fi~ure 3: shows another flushing mechanism in which the
forcing means is a bell
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~g~ shows the bell of the mechanism shown in Figure 3.
Although the present invention may be incorporated into a
flushing m~chanism of any standard toilet cistern,
operation will be described in relation to a dual flushing
mechanism. The descriptions of dual flushing mechanisms in
New Zealand Patent Specification No~ 223066 (corresponding
to Australian specification Serial No. 625514) and New
Zealand Patent Specification No. 233623/234333
(corresponding to Australian application No. 76442/91) are
hereby incorporated by way of reference.
Referring now to Figure 1, a dual flushing mechanism of the
type described in New Zealand Pat~nt Specification No.
234333 is shown. A toilet cistern 1 has an outlet 2
which cooperates with a float 3 to form a valve meansO
Connected to float 3 is a tube 4, which when lifted opens
the valve means formed by float 3 and outlet 2. A bell 5
is provided on tube 4 and is retained between rings 6 and
7. A forcing means 3 is also provided, which is supported
by ring 9 secured to tube 4. Ring 9 can be positioned
anywhere along tube 4 depending upon the desired flushing
volume. The forcing means 8 is preferably formed of a
material less dense than water, such as polypropylene, so
that the forcing means does not apply downward force to
float 3 when under water.
The full water level in the cistern is indicated by
numeral lO. If float 3 is lifted, by raising tube 4, the
valve means formed by float 3 and outlet 2 is opened.
Water flowing out of the ciskern under float 3 keeps the
float raised until sufficient downward force is applied to
tube 3 to overcome this upward force. For a half flush
~ell 5 is not til-ted and remains in the position shown in
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figure lo An air-tight seal is formed between ring 6 and
the top of bell 5. As the water level lowers about the
bell a partial vacuum coupling is created between the bell
and the falling water surface. Bell 5 thus forces down
tube 4 and float 3 as the water level lowers, to close the
valve means at the water level indicated by numeral 11.
For a full flush, bell 5 is tipped to create an air
gap between the aperture in the top surface of bell 5 and
the tube 4. Accordingly, as the water level in the cistern
falls, following the raising of float 3, no partial vacuum
coupling is formed between valve 5 and the loweriny water
level. Accordingly, the water level continues to ~all
below bell 5 until it reaches the level indicated by
numeral 12. At this point water held within forcing means
8 increasingly acts down upon float 3 as the water
contained therein is raised above the lowering water level.
This continues until the downward weight exceeds the
resistance of float 3 to closure. The float 3 then closes
on outlet 2.
Where the words "full flush" are used in this
specification reference is made to the maximum volume of
fluid flushed by a dual flushing mechanism or the volume of
water ~lushed by a single flush mechanism.
For a half flush the volume of water discharged is
indicated by the letter H. For a full flush the volume of
water discharged is indicated by the letter F. The
residual volume of water always remaining in the cistern is
indicated by the letter R.
Accordingly, the volume of water displaced for a half
and full flush can be set by altering the heights of rings
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6 and 9. An important feature is that the volume of water
flushed for a half and full flush is independent of the
capacity of the cistern.
For the embodiment shown in Figure 1, forcing means 8
is a container mounted upon tube 4 which applies downward
force on flo2t 3 as the water level drops below the level
of the water contained in container 3. It is to be
appreciated that any shape of container may be used. A
container of truncated conical form i5 however preferred.
As the forcing means 8 always ensures closure is
effected at lower water level 12, a higher head of water
can be achieved for low volume flushing cisterns. In ~he
prior art~ the level the cistern is filled to is adjusted
so that the cistern contains the required volume for a full
flush. This means that a lower static head is available
when a lower flush volume of water is used for a full
flush. Accordingly to the present invention however, the
maximum head of pressure available in a cistern can be used
for reduced volume flushing.
Figures 3 and 4 show a preferred embodiment in which
the forcing means 21 is a bell, rather than a cup as shown
in Figure 1. The mechanism shown in Figure 3 operates in
the same way as the mechanism shown in Figure 1, except
that the forcing means 21 forces tube 23 down due to the
partial vacuum coupling formed between water surface 24 and
bell 21, rathex than by a weight of water supported above
the water level (as in Figure 1).
A ring 22 is secured to tube 23. Tube 23 passes
through aperture 25 in bell 21. The top edge of the bell
adjacent aperture 25 sits on ring 22. As the water level
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in the cistern drops below ring 22, water is left between
ring 22 and the top surface of bell 21 adjacent the ring
22. The water between bell 21 and ring 22, ensures that an
air tight seal is formed therebetween. When the water
level 24 is close to the bottom of bell 21 a partial vacuum
or coupling is formed between the water surface 24 and bell
21. ~s the water level 24 lowers, bell 21 is drawn
downwardly by the partial vacuum coupling and applies
downward force to tube 23 via ring 22. This embodiment
has the advantage that the water level at which the valve
closes can be accurately controlled.
The forcing means will be positioned to reduce the
volume of water released from a cistern by a desired
amount. Typically the forcing mean~ is positioned so that
half or less of the maximum volume of the cistern is always
retained. It is to be appreciated that bell 21 or cup 8
may be formed integrally with tube 23 or 4. Alternatively,
bell 21 or cup 8 may be secured directly to tube 23 or 4 by
adhesive etc to form an airtight seal therebetween.
Where in the aforegoing description reference has been
made to intergers or components having ~nown equivalents
then such equivalents are herein incorporated as if
individually set forth, For example it is to be
appreciated that the forcing means could apply downward
force to the float via a sleeve etc without requiring the
forcing means to be secured to the tube.
Although this invention has been described by way of
example and with reference to a possible embodiment thereof
it is to be appreciated that improvements and/or
modifications may be made thereto without departing from
the scope of the invention defined in the appended claims.
