This invention relates to an improved operating mechanism for dual-flush toilet cisterns.

It is compulsory in some areas of the world to provide dual-flush cisterns, and as the authorities become more aware of the need to conserve water, more areas will prescribe dual-flush cisterns.

Flushing mechanisms for lavatories are generally unsatisfactory. They conventionally consist of mechanical linkages, and in some dual-flush systems are quite complex. Most if not all of the prior mechanisms are prone to breakdowns in particular the more complex dual-flush arrangements.

One non-mechanical flushing mechanism for conventional cisterns includes a push-button for applying an increased pressure to air in a tube, the action of which breaks a seal and allows water to flow from the cistern to the lavatory pan.

It is an object of this invention to provide an improved mechanism for actuating dual-flush cisterns.

The invention may provide, in a broad aspect, apparatus for applying a pressure in a fluid in a selected one of two systems, including a button member, movement of which causes fluid to be expelled from two .chambers or to be pressurized therein, said button member containing two passages communicating with respective chambers, each of said passages being adapted to be closed off to ensure that fluid from a predetermined chamber is expelled at a predetermined point or pressurized compared to the other.

Preferably said passages exit at the top surface of said member and are closed by a digit being placed over a respective one to act as a seal.

Preferably, ridge means is provided between said apertures to prevent accidental simultaneous sealing of both apertures.

Preferably, said chamber is adapted to communicate with respective air-pressure operated mechanisms for dispensing fluid.

Preferably, the apparatus is used to operate a dual flush toilet systems.

An embodiment of the invention which may be preferred, will be described in detail hereinafter, with reference to the accompanying

drawings, in which:-

Fig. 1 is a perspective view of a button unit in accordance with an embodiment of the invention;

Fig. 2 is an exploded perspective view of the nit of Fig. 1; and

Fig. 3 is a vertical section through the unit of Fig. 1.

Fig. 4 is one example of a dual flush mechanism capable of adaptation and operation by the mechanism of the invention.

The unit 10 includes a button 12 which is adapted to move axially relative to a casing 14. button 14 has an annular flange 16 with an 0-ring 17 located to seal against the internal wall of a first chamber 18 of casing 14.

A second, flange 20 is located on the base of button 12. In this preferred embodiment the flange 20 is secured to button 12 by a countersunk screw 22. An 0-ring 24 is located to seal flange 20 against the internal wall of second chamber 26 of casing 14. The second chamber 26 is provided with an air bleeding hole 60 to allow the seal flange 20 to return to the operating position abutting the underside of the annular flange 32.

A spring 28 is located in chamber 26 between flange 20 and a cap 30 which is adapted to be screwed onto the base of casing 14. Spring 28 normally biases button 12 upwards to the position where the top of flange 20 abuts the underside of annular flange 32 which separates chambers 18 and 26.

At the top of casing 14 there is a retainer cap 34 which is adapted to be screwed onto casing 14. Nut 36 allows the unit 10 to be located in an aperture in a lavatory cistern, it being adapted to screw onto cap 34.

Casing 14 has a spigot 38 extending therefrom, communicating with chamber 18. Casing 14 also has a similar spigot 40 extending from it, which communicates with chamber 26.

Button 12 has two passages 42,44 therein. Passage 42 communicates with chamber 26, and passage 44 communicates with chamber 18. Passages 42,44 are open to the air at respective apertures 46,48 on the top surface 50 of button 12. A diametric ridge 52 separates apertures 46,48.

In use, a first tube 62 is attached at one end to spigot 38

and at the other end to a conventional air- pressure operate mechanism Fig. 4 for breaking a seal and dispensing a cistern of predetermined amount of water. A second tube 63 is attached a one end to spigot 40 and at the other end to a conventiona air-pressure operated mechanism Fig. 4 for breaking a seal an dispensing a predetermined amount of water from a cistern.

We shall say that the tube attached to spigot 38 provides fo a 'full' flush, and that leading from spigot 40 providing a 'half flush.

To actuate the 'full flush', a user will place a digit ove aperture 48 on the top surface 50 of button 12. That seals th passage 44. When the button 12 is pushed down, the compressiv effect of the movement of flange 16 will increase pressure in the tube attached to spigot 38, and will allow the mechanism to which the tube is attached to break a seal and dispense a full amount of water from a cistern into a pan.

For a 'half flush, the digit would be placed over aperture 46. The apparatus would operate in a similar way as described for aperture 48.

Ridge 52 is positioned to prevent accidental coverage of both apertures with a single digit.

Preferably, all the components of the unit 10 are formed from brass, except the 0-rings 17,24 the spring 28 (which may be of spring steel) and the screw 22, which may also be brass.

More preferably, all the components of the unit 10 are formed of plastic, except the 0 rings and springs and screw.

It can be seen that the present invention provides an improved and elegantly simple mechanism for a dual flush system.