BACKGROUND TO THE INVENTION It is becoming ever more important that fresh water supplies be conserved in urban areas. One approach to achieve conservation has been directed towards the use of less water from water cisterns in toilets.

A general approach has been widely adopted to provide cisterns which will allow two different volumes to be delivered from the cisterns each of which can separately be selected by the toilet user.

OBJECT OF THE INVENTION It is an object of the present invention to provide a mechanism whereby this can be satisfactorily achieved.

SUMMARY OF THE INVENTION According to this invention there is provided a cistern flushing mechanism comprising

a flushing valve and a first float assembly including an upstanding valve stem within a casing the valve stem connectable to an operating handle a plunger releasably securable to the casing connected to a second operating handle and movable selectively with or longitudinally relative to the valve stem a second float movable relative to the casing to operate a latching means for securing the plunger to the casing with the second float in a raised position, the plunger and first float assembly co-operating for relative downward movement of the plunger to cause closure of the flushing valve characterised in that the mechanism includes means for damping the closure movement of the valve at least during half flush operations.

Further features of this invention provide for the means to be the plunger and valve stem assembly or casing providing co-operating surfaces shaped to induce reduction in pressure in a space between them when separated and for these surfaces to be located within the casing, for the surfaces to be outwardly tapering and located on the lower end of the plunger and partway along the length of the valve stem. The space will be vented when reaching a predetermined size.

The invention further provides for the plunger to be weighted, for the plunger to be a tube slideable relative to the valve stem or a radial flange extending from such a tube.

The invention also provides for the second float to be annular and located around an extension to the casing, to have upper and lower sections with an opening through the wall between the sections and for the float to be adjustable in height relative to the casing.

Still further features of this invention provide for the second float to be adjustable on a guide slideable on the casing with the guide including means for engaging the latching means and for the latching means to be a lever pivotally supported on the casing and carrying a suitable slide or roller or other friction reducing member contactable by the guide.

Still further features of this invention provide for there to be a pair of latching means positioned on the casing diametrically opposed to each other with respect

to the valve stem and for the plunger to have a rack formed thereon engageable by a pawl formed on the latching lever.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features of this invention will become apparent from the following description of preferred examples described below with reference to the accompanying drawing in which FIG 1 shows a longitudinal section of one form of cistern flushing mechanism; FIGS 2 and 3 are similar views of an alternative embodiment showing the valve open and closed ; and DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS Referring to Fig 1 the flushing mechanism (1) includes a flushing valve seat (2) forming part of a fitting (3) to be located in sealing engagement with an aperture through the base of a cistern (not shown). The fitting (3) provides, in the usual way, a base to which a casing (4) for the valve assembly is releasably attached.

In this embodiment the casing (4) is stepped at (5) for the purposes described below.

A flushing valve (7) closes on seat (2) and has an upstanding hollow valve stem (8) which forms a cistern overflow pipe in well known manner. The valve stem (8) carries adjacent the valve (7) an air float (9) also in conventional manner.

This float operates normally to prevent closure of the valve (7) onto seat (2) prior to a full flush operation of the mechanism.

The upper free end of the valve stem (8) is adapted to be connected to a manipulating handle (not shown) which will be mounted to the outer front face of the cistern or to the cistern lid.

Slidable on and guided by the valve stem (8) is a plunger (10) in the form of a hollow rod (11). This rod has a weighted collar (12) which moves in a recess (13) provided therefor in the upper end of casing (4).

The free end of rod (11) carries a stop (14) which engages the upper end of the casing to limit the downward travel of the rod.

The upper end of the rod (11) is engaged by the end (15) of a lever (16) forming part of a linkage to a second manipulating handle (not shown).

The step (5) provides a mounting (17) for a cranked catch (18) one arm (19) of which is movable to pass through an appropriate slot in the casing to engage a peripheral rack or other detent providing formation (13A) on the lower end of the hollow rod (11) to releasably secure the latter to the casing (4) when the hollow rod is in its raised position.

The other arm (20) of catch (18) carries a protrusion (21) movable by the stepped end (22) of a tubular member (23) and preferably affords reduced friction contact between the components. The tubular member (23) is slideable on the outer surface of the upper end of the casing. This movement will pivot the cranked catch (18) to move the arm (19) through the slot in the casing and allow the end of arm (19) to run against the hollow rod (11). The member (23) is externally screwthreaded to be engaged by a second tubular member (24) which carries a second float (25). This arrangement enables the height of float (25) to be adjusted in the flushing mechanism. Preferably a catch (18) will be provided on each side of the assembly for symmetrical operation. The members (23) and (24) may alternatively be releasably and longitudinally adjustably connected together through a rack and pawl arrangement.

The lower part of the casing (4) and the valve stem (8) provide an annular chamber (26) for the air float (9).

Adjacent the lower end of the hollow rod (11) a formation (27) provides an outwardly tapered surface. This surface co-operates with the surface (28) formed around the outwardly expanding section of the wall of the hollow valve stem (8). Complementary shoulders (29) are provided on these two components which abut when the hollow rod (11) is raised by lever (16) on operation of the second handle (not shown). The exterior surface of the valve stem is stepped inwardly at (29A).

It will be appreciated that separation of the tapered surfaces will tend to provide an evacuated chamber between them exercising a force tending to draw them

together. This chamber will be vented when the end of surface (27) reaches the step (29A) on relative movement of surfaces (27) and (28). The use to which this is put is explained below.

In use the flushing mechanism can be operated to provide either a full flush or a half-flush."Half"here is meant to be a part flush which can be varied, as described below, by varying the relative position of the second float (25) on the tubular member (23).

Initially the cistern is filled and the valve (7) closes onto the seat (2) around the outlet from the cistern. The plunger (10) has fallen to its lowest position on the valve stem (8). Water filling the cistern lifts float (25) and consequently the second tubular member (24) is moved upwardly. As a result when the float (25) has risen to its uppermost position the protrusion (21) on arm (20) will have been moved pivoting arm (20) and causing the arm (19) to contact the hollow rod (11) through the slot in the casing.

The movement of float (25) and tubular member (24) is small and need be only enough to cause pivoting of the catch.

The cistern is ready to flush.

For a full flushing, operation is effected by operating the handle connected to the valve stem (8). The valve (7) is lifted off its seat and float (9) is located in the chamber (26) formed in the casing. The link (16) remains in place because its associated handle has not been moved.

As the cistern empties the valve (7) drops back onto its seat (2) when the float (9) loses its buoyancy effect. This is the normal operation of this kind of flushing valve.

However, simultaneously with the above the float (25) drops with lowering of the water level in the cistern and moves second tubular member which results in pivoting of the catch (18) to swing arm (19) out of contact with the hollow rod (11).

The cistern flushes fully, valve (7) drops to the closed position and the float (25) rises with the appropriate water level. Initially float (9) does not rise as it is held in

position by the downward thrust of the water in the cistern. When the valve (7) is lifted so that the float is raised into the chamber in the casing out of the flow path of the water stream the buoyancy of the float (9) becomes effective to retain the valve (7) open.

The rising of the second float (25) pivots the catch (18) and the arm (19) again engages against the hollow rod (11).

When a half flush is required, the half flush handle is operated. This lifts the plunger (10) and valve (7) together. The normal linkage to the full flush operating handle at this time will be moved with the half flush handle. The movement of the hollow rod (11) enables the arm (19) of the catch (18) to engage with the rack (13A) on the plunger (10) of the hollow rod (11).

The cistern begins to flush and lowering of the water level results in dropping of float (25) and the second member (24). This causes release of the catch (18) from the raised plunger (10) which drops under the influence of weight (12).

It is now that the effect of the two tapered surfaces (27) and (28) takes place.

Downward movement of the hollow rod (11) causing separation of the surfaces (27) and (28) drags the valve stem (8) and float (9) from the raised position where they would normally be held until the cistern has been fully flushed. The valve stem (8) is held by suction to follow the hollow rod (11) and the weight (12) is chosen to ensure that valve (7) is closed after half-flushing the cistern. When the end of surface (27) reaches the step (29A) the space under reduced pressure is vented and a small amount of water will enter this space.

The release of the vacuum between the tapered surfaces also tends to avoid the too rapid closing of valve (7). If necessary this can be further avoided by a cushioning chamber being included between the outer wall of the float (9) and the casing (4) or the valve and the fitting (3).

The rise in the water level lifts float (25) and the catch (18) locks the casing and hollow rod together so that the full flush mechanism can again be operated without affecting the half-flush mechanisms.

Referring to Figs 2 and 3 the flushing mechanism (101) illustrated includes a flushing valve seat (102) forming part of a fitting (103) to be located in sealing

engagement with an aperture through the base of a cistern (not shown). The fitting (103) provides, in the usual way, a base to which a casing (104) for the valve assembly is releasably attached.

In this embodiment the casing (104) is stepped at (105) and (106) for the purposes described below. However it will be appreciated that, if desired, the casing can be of the same diameter throughout its length.

A flushing valve (107) closes on seat (102) and has an upstanding hollow valve stem (108) which forms a cistern overflow pipe in well known manner. The valve stem (108) carries adjacent the valve (107) an air float (109) also in conventional manner. This float operates normally to prevent closure of the valve (107) onto seat (102) prior to a full flush operation of the mechanism when a full flush is necessary.

The upper free end of the valve stem (108) is adapted to be connected to a manipulating handle (not shown) which will be mounted to the outer front face of the cistern or to the cistern lid.

Slidable on and guided by the valve stem (108) is a plunger (110) on the end of a hollow rod (111). The plunger is weighted as indicated at (112) and a peripheral rack formation (113) is provided on the outside of rod (111). The free end of the rod (111) is located normally by the stop (114) on the end of casing (104).

The rod (111) is engaged by the end (115) of a lever (116) forming part of a second linkage to a second manipulating handle (not shown).

The steps (105) and (106) in the casing provide chambers (117) and (118) in which the float (109) and plunger (110) can move during operation of the mechanism as described below.

The step (106) provides a mounting for a pair of latching means (119). Each latching means (119) consists of a lever (120) pivotally supported on the step (116) of the casing (104). The lever (120) carries an upper roller (121) and lower roller (122). Opposite these rollers (121) and (122) is a pawl (123). Pivoting of the levers (120) causes the pawl (123) to pass through a slot in the casing (104) to engage the rack formation (113) when the rod (111) is raised. This is described more fully below. The lever (120), rollers (121) and (122) are

designed to enable the lever (120) to pivot the pawl (123) when the plunger (110) is moved upwardly but to lock the rod (111) to the casing (104) and prevent unintentional downward movement of the plunger (110). The pair of latching means provides symmetry to the assembly but only one such means is essential to the operation of the valve assembly.

On the outside of the casing (104) operatively above the latching means (119) is slideably supported a tubular guide (124) which has a radially outwardly extending projection carrying cam surface (125). This latter is positioned to engage the upper roller (121) of each latching means to assist in relative movement between the surface (125) and the respective rollers (121) causing the pivoting movement of the lever (120) to enable the pawls (123) to engage the rack formation (113).

The upper end of guide (124) is screwthreaded or racked so that a second float (126) can be adjustable positioned thereon.

This second float (126) may be divided into two chambers (127), (128) with apertures (129) through the outer wall of the float. This divides the float into an upper air containing chamber (127) and a lower water filled chamber (128). The effect of this construction of the float is to ensure a positive downward movement of the guide (124) as the water level drops. The water trapped in the float increases the weight acting on the float. When the water level rises the water becomes part of the mass of water in which the float moves and thus does not resist the buoyancy effect of the air in the upper chamber (127). This construction is not essential and a simple air trap float can be used. In the latter case only a single step need be provided in the shape of the casing as no space for the water filled chamber is necessary.

In use the flushing mechanism can be operated to provide either a full flush or a half-flush."Half"here is meant to be a part flush which can be varied, as described below, by varying the relative position of the second float (126) on the guide (124).

Initially the cistern is filled and the valve (107) closes onto the seat (102) around the outlet from the cistern. The plunger (110) has fallen to its lowest position in the bottom of chamber (118). Water filling the cistern lifts float (126) and consequently guide (124) is moved upwardly. As a result when the float (126)

has risen to its uppermost position and surfaces (125) carried by the tubular guide (124) have driven rollers (121) to pivot the levers (120) so that pawls (123) engage the hollow rod (111).

The movement of float (126) and guide (124) is small and need be only enough to cause pivoting of the levers (120).

The cistern is ready to flush.

For a full flushing, operation is effected by operating the handle connected to the valve stem (108). The valve (107) is lifted off its seat and float (109) is located in chamber (107). The link (106) remains in place because its associated handle has not been moved.

As the cistern empties the valve (107) drops back onto its seat (102) when the float (109) loses its buoyancy effect. This is the normal operation of this kind of flushing valve.

However, simultaneously with the above the float (126) drops with lowering of the water level in the cistern and lower surface (125) contact rollers (122), releasing pawls (123).

The cistern flushes fully, valve (107) drops to the closed position and the float (126) rises with appropriate water level. initially float (109) does not rise as it is held in position by the downward thrust of the water in the cistern. When the valve (107) is lifted so that the float is raised into chamber (107) out of the flow path of the water stream the buoyancy of the float (109) becomes effective to retain the valve (107) open.

The movements of the guide, rollers, levers and pawls does not affect the filling of the cistern. Raising of float (126) causes the pawls (123) engage the rod (111).

When a half flush is required, the half flush handle is operated. This lifts the plunger (110) and valve (107) together. The normal linkage to the full flush operating handle at this time will be moved with the half flush handle. The pivoted levers (121) engage the pawls (123) with the rack formation (113) and this holds the plunger (110) raised in chamber (108).

The cistern begins to flush and lowering of the water level results in dropping of float (126) and guide (124). This causes release of the raised plunger (110) which drops under the influence of weight (112) to contact the top of the lifted float (109). This in turn disturbs the buoyancy of float (109) and valve (107) is forced to close against the flow through the cistern outlet.

The cistern refills after only a part flush which is determined by when the adjustable upper float drops to activate the latching mechanism.

Once the cistern has refilled it is ready for the next flushing operation. it is advantageous to damp the closing movement of the valve (107) after a half flush operation to reduce the effect of the weight of water in the cistern acting to close the valve (107). Figure 3 indicates two alternative means of achieving this desired result. The choice of which of these constructions, or further alternative constructions, will depend on circumstances such as difficulties in tooling and whether or not the damping action is to be effective on both flushing operations or only on the half flush operation.

Figure 3 shows the position of the components after the plunger (110) has dropped to its lowest point but before the flushing valve (107) has completely closed. A damping action on the final closing of valve (107) is achieved by the provision of a chamber (130) between the outside of float (109) and the casing (104). The restricted outlet (131) from the chamber (130) provides the damping effect.

This damping effect will take place during both. full and half flush operations.

Alternatively a damping chamber (132) is created between the hollow valve stem (108) and the rod (110). This damping chamber is effective for half flush operation only. In this operation the water level (133) remains above the chamber (132). However, on full flush operation the water level drops below the bottom of chamber (132) and there is no damping effect on the movement of valve (107) at final closure.

Other means for damping may be incorporated into the cistern flushing mechanism if these prove to be more convenient.

The invention provides a compact effective unit for a dual flushing operation. Its symmetrical construction lends itself to smooth operation and the provision of a skirt depending from upper float (126) hides the latching mechanisms from view giving the mechanism an attractive overall appearance.