AU664095B2 - A cistern mechanism - Google Patents

Description

-1- The present Invention relates to dual flush cistern mechanisms and, In particular, to a flush volume adjusting attachment able to be retrofitted to a known dual flush cistern mechanism.

Australian Patent No. 559,249 (Application No. 32581/84) describes a known dual flush cistern mechanism. Essentially this mechanism takes the form of a flush valve which Is operable by a generally vertical valve stem. The valve stem Is position.d above the valve. Water Is admitted Into the cistern via an inlet valve which Is opened and closed by one end of a pivoted float arm. The other end of the float arm carries a float which floats on the water within the cistern.

Consequently the float arm rises and falls In accordance with the level of water in the cistern, A flush selector Is used to determine whether a full flush or a partial flush Is to be operated. The flush selector has a latch mechanism including at least two Inter-engagable pawls. One of these pawls Is mounted at one end of a pivoted knock down arm. The other end of the pivoted knock down arm carries an upwardly facing water retaining receptacle which Is at least partially open at Its top so that any water located above the receptacle can flow Into the receptacle.

Also provided Is a lifting mechanism which enables the cistern to be flushed, To Initiate the flushing action, tho lifting mechanism is operated so as to raise the valve stem which thereby opens the flush valve.

Normally -he flush valve closes under the weight of the valve stem when the flow of water through the flush valve reduces below a predetermined value at which time the cistern Is nearly empty. During this action the knock down arm Is latched In position and Is unable to pivot.

In order to bring about a partial flush, the flush valve Is prematurely closed at a first levl of water In the cistern. This Is I ibought about by the flush selector latch being released which allows the knock down arm to pivot with the falling water level In the cistern under the Influence of the weight of water in the receptacle. When the first lev1 of water Is reached the knock down arm strikes the valve stem (or a small projection thereon) thereby prematurely closing the flush valve.

This mechanism works well and has been commercially successful.

However, in recent times some water supply authorities in both Australia and New Zealand have changed their regulations as to the standard volumes required for a full flush and a partial flush. The Impetus for HRW/0584o i such change Is to reduce water consumption and thereby postpone the necessity to build further water storage dams.

Hithereto, the standard full flush was from approximately 9 litres to 11 litres whilst the standard partial flush was approximately litres. The new standard to which such authorities are moving In piecemeal fashion is now generally 6 litres for a full flush and 3 litres for a half flush. The situation Is further complicated by some authorities stipulating an upper limit to the flush volumes. Hithereto, flush volumes have been specified as a minimum volume regarded as being adequate to reliably flush a toilet bowl, and such volumes have now been reduced, in part owing to Improved toilet bowl design.

However, under the impetus of water saving, maximum flush volumes are Increasingly being specified in order to prevent more than a prescribed maximum volume of water being used for a full flush and a lesser prescribed maximum volume of water being used for a partial flush.

Although prima facle, under the Influence of Closer Economic Relations, the purchasers of cisterns in Australia and New Zealand can be regarded as a single market, the area covered by a single water supply jurisdiction Is relatively small. In particular, such jurisdictions are often limited to a single city or rer' n and the requirements of each jurisdiction are not identical. This makes it very difficult to achieve high volume, and therefore low cost, production levels since, in theory at least, different cisterns should be sold In different water supply jurisdictions. For the above reasons It is highly desirable to have a cistern mechanism which enables the flush i volumes to be adjusted or selected without the need to alter the overall configuration of the cistern itself.

Furthermore, there are a large number of cisterns already Installed and such cisterns and their operating mechanisms have a relatively long operating life. Coupled with the supply authority's 4 desire to reduce water consumption Is a move towards charging water .f consumers on a volume basis rather than such consumers being rated on a property valuation basis.

For all the above reasons, there Is an Increasing demand for an attachment which can be retrofitted to an existing Installed cistern, or can be easily incorporated Into an existing cistern production line, so as to reduce the flush volumes at which the cistern operates.

HRW/0584o 1 i I- -3- It is the object of the present invention to respond to the above mentioned commercial pressures by the provision of a retrofittable flush volume adjusting attachment for a known dual flush cistern mechanism, the attachment being able to be retrofitted to an existing installed cistern, fitted in the factory so as to convert a cistern 6 to particular flush volumes, or fitted by a plumber at its time of installation so as to comply with the then current regulations of the local water supply authority, bearing in mind that the cistern may be manufactured and supplied to retailers within the authority's jurisdiction prior to the implementation date of revised regulations of the authority.

In accordance with one aspect of the present invenition there is disclosed a retrofittable partial flush volume adjusting attachment for a dual flush cistern mechanism known per se, said mechanism comprising a flush valve operable by a generally vertical valve stem positioned above said valve, an inlet valve operable by one end of a pivoted float arm, the other end of which carries a float, and a pivoted 1i knockdown arm having a flush selector latch pawl at one end and a first upwardly facing at least partially open topped water retaining receptacle at the other end, said cistern mechanism being partially flushable by a lifting mechanism arranged to raise said valve stem and open said flush valve, said flush valve being normally closable Sunder the weight of said valve stem when the flow of water through said flush valve 20 reduces below a predetermined value, and said flush valve being prematurely closable at a first level of water in said cistern by said flush selector latch pawl releasing said knockdown arm which falls with the water level in said cistern under the influence of the weight of water in said receptacle to strike said valve stem; said attachment comprising a second upwardly facing at least partially open topped water retaining receptacle attachable to said knockdown arm other end to make said knockdown arm less buoyant and close said flush valve at a second, higher, water level, Preferably a knockdown rod is attachable to said float arm above said valve stem to strike said valve stem and close said flush valve at a third water level lower than said second level, In accordance with another aspect of the present invention there is disclosed a S3 method of reducing tne partial flush volume of a dual flush cistern having a pivoted 'knockdown arm including a first upwardly facing at least partially open topped water retaining receptacle, said arm in operation striking a valve stem of said dual flush cistern to prematurely close same; said method comprising the step of attaching a second upwardly facing at least partially open topped water retaining receptacle 3o adjacent to the free end of said pivoted knockdown arm.

O INlIBI0OIO2:cg Ai 4 One embodiment of the present invention will now be described with reference to the drawings in which: Fig. 1 is a schematic front elevation of a cistern illustrating various water levels, a Fig. 2 is a partially cut away front elevational view of the cistern of the preferred embodiment, Fig. 3 is a plan view of the interior of the cistern of Fig. 2, the lid of the cistern being removed, and Fig. 4 is a cross sectional view taken along the line IV-IV of Fig, 3, As seen in Fig. 1, a dual flush cistern 10 can have a number of possible water levels, The uppermost level 5 is the level at which the cistern is full, The lowermost level 4 is the level at which, during flushing, the flow of water through the flush valve reduces in volume sufficiently to enable the flush valve to close under the weight of the valve stem, Accordingly, the normal volume (9 litres) of the full flush is the volume 1i indicated by the letter A in Fig. 1. In order to bring about a partial flush of 4.5 litres the valve stem is prematurely knocked down at the first water level 1, Thus the volume indicated by the letter B in Fig. 1 corresponds to approximately 4,5 litres.

In order to bring about a reduced volume flush of approximately 3 litres, Sstarting from the same full level 5, it is necessary to prematurely close the flush valve when the water reaches tile second level 2, Thus this reduced partial flush volume is indicated by the letter D. Similarly, in order to bring about a full flush volume of only 6 litres starting from the full water level 5, it is necessary to close the flush valve when the water level in the cistern 10 reaches the third level 3. Thus the volume of water corresponding to a 6 litre full flush is indicated by the letter C in Fig. 1.

The preferred cistern mechanism for bringing about either of these operating regimes is illustrated in Figs. 2 to 4 inclusive, As explained above, the basic operating principle of the cistern mechanism is as described in the above mentioned Australian Patent No. 559,249 (Application No, 32581/84). Essentially this cistern mechanism takes the form of a flush valve 11 which S3 is operable by a generally IN::'"~UBOOIOOQ14: vertical valve stem 12. The valve stem 12 Is positioned directly above the valve 11, Water Is admitted Into the cistern 10 via an Inlet valve 13 which Is opened and closed by one end 15 of pivoted float arm 14.

The other end 16 of the float arm 14 carries a float 17 which floats on the water within the cistern 10, Consequently, the float arm 14 rises and falls in accordance with the level of water (not illustrated) in the cistern 10, A flush selector 21 mounted In the cistern lid 28 is used to determine whether a full flush or a partial flush Is to be operated.

The flush selector has a latch mechanism 22 Including at least two Inter-engagable pawls 23,24. One of these pawls 24 is mounted at one end 19 of a pivoted knock down arm 18.

The other end 20 of the pivoted knock arm 28 carries a first upwardly facing water retaining receptacle 25 which Is open at Its top so that any water located above the receptacle 25 can flow Into the receptacle 25. Also provided is a lifting mechanism 26 which enables the cistern to be flushed.

To initiate the flushing action the lifting mechanism 26 is operated so as to raise the valve stem 12 which thereby opens the flush valve 11. Normally the flush valve 11 closes under the weig:t of the valve stem 12 when the flow of water through the flush valve 11 reduces Sbelow a predetermined value at which time the cistern 10 is nearly empty. During this action the knock down arm 18 Is latched In position via pawl 24 and is unable to pivot.

In order to bring about a partial flush, the flush valve Is prematurely closed at a first level of water in the cistern. This Is bought about by the flush selector latch mechanism 22 being released which allows the knock down arm 18 to pivot In an anti-clockwise direction as seen In Fig. 2 with a falling water level In the cistern The partially bouyant knock down arm 18 pivots under the Influence of the weight of water In the receptacle. When the first level of water Is reached the knock down arm 18 strikes a small projection 27 on the valve stem 12 to thereby prematurely close the flush valve 11.

As best seen In Figs. 2 and 3, a second receptacle 30 having a pair of spaced apart downwardly facing U-shaped arms 31 and 32, and a single upwardly facinq U-shaped arm 33 Is snap-engagable with the free end of the first receptacle 25. Both the first and second receptacles 30 face upwardly and have an open top so that when the water in the ItRW/0584o cistern 10 rises above the receptacles 25, 30 then they both fill with water.

A second attachment in the form of a generally planar knock down rod 36 is also snap-engagable with the float arm 14 at a location, as best seen in Fig. 3, immediately above the valve stem 12.

The function of these two attachments is as follows. The second receptacle 30 when full of water changes the buoyancy of the knock down arm 18. As a consequence, the knock down arm 18 when free to pivot, floats at a lower height in the water within the cistern Accordingly, the undersurface of the knock down arm 18 strikes the valve stem projection 27 sooner than would be the case if the second receptacle 30 were not present. As a consequence, the flushing action is prematurely interrupted at water level 2 in Fig. 1 rather than at water level 1.

It will be apparent to those skilled in the art that the second receptacle 30 Is attached to the edge of the first receptacle furthest from the point about which the knock down arm 18 pivots. This gives a maximum movement for a given size of receptacle 30. This allows the receptacle 30 to be as small as possible.

Similarly, as the float 17 falls with the level of water in the cistern during the flushing operation, so the knock down rod 36 approaches the upper end of the uplifted valve stem 12. The length of the knock down rod 36 can be arranged so that the knock down rod 36 strikes the upper end of the valve stem 12 and closes same when the water level in the cistern is at level 3 as illustrated in Fig. 1. In consequence, the volume of the full flush dnlivered by the cistern mechanism is reduced.

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.

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IHRW/0584o

Claims (7)

1. A retrofittable partial flush volume adjusting attachment for a dual flush cistern mechanism known per se, said mechanism comprising a flush valve operable by a generally vertical valve stein positioned above said valve, an inlet valve 6 operable by one end of a pivoted float arm, the other end of which carries a float, and a pivoted knockdown arm having a flush selector latch pawl at one end and a first upwardly facing at least partially open topped water retaining receptacle at the other end, said cistern mechanism being partially flushable by a lifting mechanism arranged to raise said valve stem and open said flush valve, said flush valve being normally closable under the weight of said valve stem when the flow of water through said flush valve reduces below a predetermined value, and said flush valve being prematurely closable at a first level of water In said cistern by said flush selector latch pawl releasing said knockdown arm which falls with the water level in said cistern under the influence of the weight of water in said receptacle to strike said valve stem; said 16 attachment comprising a second upwardly facing at least partially open topped water retaining receptacle attachable to said knockdown arm other end to make said knockdown arm less buoyant and close said flush valve at a second, higher, water level.

2. An attachment as claimed in claim I wherein said second water retaining receptacle is attachable to that edge of said first water retaining receptacle 20 furthest from the point at which is knockdown arm is pivoted. 3, An attachment as claimed in claim 1 or 2 wherein a knockdown rod is attachable to said float arm above said valve stem to strike said valve stem and close said flush valve at a third water level lower than said second level, 4, An attachment as claimed in claim 3 wherein said knockdown rod pivotally depends from said float arm, An attachment as claimed in claim 3 or 4 wherein the flush volumes corresponding to said third and second levels are in the ratio of approximately 2 to 1.

6. An attachment as claimed in claim 5 wherein said flush volumes are 6 litres and 3 litres respectively, so 7. A method of reducing the partial flush volume of a dual flush cistern having a pivoted knockdown arm including a first upwardly facing at least partially open topped water retaining receptacle, said arm in operation striking a valve stem of said dual flush cistern to prematurely close same; said method comprising the step of attaching a second upwardly facing at least partially open topped water retaining as receptacle adjacent to the free end of said pivoted knockdown arm.

8. A method as claimed in claim 7 wherein said second receptacle after attachment becomes the free end of said pivoted knockdown arm. 9 -11, tu'a60b1001 1- 1 Pr; -7 I~ICiC-~==t--i~ 9, A method as claimed in claim 7 or 8 comprising the step of reducing the full flush volume with which a dual flush cistern flushes, said method comprising the step of attaching a knockdown rod to an inlet valve closing float arm of said cistern at a location above said valve stem, B 10, A method as claimed in claim 9 wherein said knockdown rod pivotally depends from said float arm. 11, A method as claimed in claim 9 or 10 wherein said full and partial volumes are in the ratio of approximately 2 to 1,

12. A method as claimed in claim 11 wherein said full volume Is 6 litres and said partial volume is 3 litres.

13. A retrofittable flush volume adjusting attachment substantially as described with reference to the accompanying drawings,

14. A method of reducing the flushing volumes of a dual flush cistern, said method being substantially as described with reference to the drawings, 1 DATED this Sixth Day of September 1995 Caroma Industries Limited i Patent Attorneys for the Applicant 20 SPRUSON FERGUSON %Ij h6- -11 MAIIRMANAAALIA ;I I A Cistern Mechanism ABSTRACT A retroflttable attachment to reduce the flushing volumes of a dual flush cistern Is disclosed. The partial flush volume Is reduced by an open topped container (25) which Is attached to the free end of a pivoted knock down arm The full flush volume Is reduced by a knock down rod (36) which Is pivotted and hangs from the float arm (14) immediately above the valve stem (12). (Fig. 2) i' \:l HtlR/0584 i