GB2276640A - W.C. cistern - Google Patents

Abstract

An improvement in the W.C. cistern described in GB 2205595 includes first and second devices to initiate a discharge of the vessel by syphonic action. Operation of the first such device initiates a discharge which continues until the cistern is empty, but operation of the second such device both initiates a discharge and actuates a means to halt that discharge before the cistern is empty. The two devices may each be in the form of buttons (27, 39), depression of which squeezes bellows (25, 26). After operation of the second device, discharge may be halted by breaking the syphonic action when the liquid in the cistern falls to a certain level. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO CISTERNS This invention relates to cisterns, for water closets or the like. It relates particularly to so-called dual-flush cisterns, that is to say cisterns that can be operated so as to deliver either a full flush in which substantially the full liquid contents are discharged, or a short flush in which the discharge is halted before the cistern is empty. A common characteristic of known dual-flush cisterns is that they have had only a single handle or other discharge-initiating device, just like conventional cisterns. The only distinguishing feature has often been a small label stuck to the outside of the cistern, instructing the user to depress the handle and release immediately - i.e. the normal method of operation - if a short flush is required, but to depress it and hold it down for a long flush.Unfortunately many users do not or cannot read such a notice, with the result that when a long flush is required they operate the handle in the normal way, so initiating a short flush which is insufficient and therefore wastes water.

The present invention arises from appreciating the advantage of applying the opposite logic to a dual-flush cistern, so that the user must positively decide which one of the two flushes short or long - to select, and preferably for the long flush to be in some way preferential, so that an inattentive user tends to select the long flush. The invention is defined by the claims, the contents of which are to be considered as included within the disclosure of this specification, and the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a cistern schematically; Figure 2 shows the short flush valve in perspective and in the closed position, and Figure 3 is similar to Figure 2 but shows the valve in the open position.

The cistern 1 of Figure 1 contains a sinuous-shaped syphon conduit 2. The cistern is filled from a mains water supply 3 by means of an inlet 4 controlled by a conventional ball valve 5, and reference 6 indicates the water level in the cistern when it is full. The syphon conduit 2 is essentially of the kind described in Patent Specification GB-B-2205595, and has an open inlet 7 located at a low level 8 within the cistern. At its other end the conduit 2 passes through a seal 9 in the base of the cistern, and continues in direction 10 towards a point of use. When the water falls to level 8, the cistern is effectively empty and any syphonic action within conduit 2 is broken: in the course of a full flush, the water within the cistern falls to this level.

Following a flush, and as described in detail in Specification 2205595, as the water rises to level 6 within the body of the cistern it also rises to equal levels 12, 13 and 14 in limbs 15, 16 and 17 of conduit 2. In this process the pressure of the air trapped in the region 19 of the conduit, between limbs 15 and 16, is raised. A pressurised airlock is thus set up, preventing a syphonic discharge through the conduit until it is broken. During the filling process the water also fills a "U"-shaped vent tube 20 having an inlet 21 to limb 16 just above level 13, and an outlet 22 to limb 17 just above level 14. An air tube 24 connects vent tube 20 to full flush bellows 25. One end 28 of a further tube 29 is connected at high level to the final limb 18 of conduit 2. The other end of tube 29 is located at a lower level 31 within the cistern, and carries a flap valve 32.This valve is operable by a plunger 33 carried by valve-operating bellows 34, which are connected pneumatically to short flush bellows 26 by a tube 35. As indicated at 30, in the course of its length tube 29 passes above the full water level 6, to avoid the possibility that water might discharge continuously from the cistern if the valve 32 should start to leak.

A full flush operating button 27 carries a plunger 23 which engages main flush bellows 25, and a short flush operating button 39 carries plungers 40 and 41 engaging the main and short flush bellows 25 and 26 respectively. Buttons 27 and 39 may typically be mounted on the cistern wall 11 above the full water level 6.

As shown, and in practice, button 27 will typically be the larger of the two, or otherwise more prominent than button 39, but what is essential is that when either button is fully depressed, it squeezes main bellows 25, so expelling enough air down tube 24 to expel all liquid both from tube 24 and from the connected vent tube 20. This allows the pressurised air in region 19 to escape to the ambient pressure in limb 18, thus causing a syphonic discharge to begin through conduit 2. When the main button 27 is pressed, only bellows 25 are squeezed, and a full flush results with the water falling to level 8 until the syphonic action within conduit 2 is broken. When the short flush button 39 is pressed, the short flush bellows 26 are squeezed also by plunger 40 expelling air down tube 35 so as to expand the bellows 34 and so cause the plunger 33 to open the flap valve 32 as shown best in Figure 3. A non-return valve 37 and an air bleed 38 in tube 35 regulate the rate at which bellows 34 then collapse again, so that plunger 33 continues to hold flap valve 32 at least partly open long enough for the water to fall at least to level 31 as the cistern discharges, but allows the valve to re-close fully before the cistern can refill again. The result is that when the discharging water falls to level 31, air reaches inlet 28 in limb 18 of conduit 2 by way of the open valve 32 and tube 29.

Syphonic action therefore ceases after only a fraction of the water within the cistern has been discharged: the result is a short flush.

Claims (13)

1. A cistern for a WC or the like, including first and second devices to initiate a discharge of the vessel by syphonic action, in which operation of the first such device Initiates a discharge which continues until the cistern is empty, whereas operation of the second such device both initiates a discharge and actuates means to halt that discharge before the cistern is empty.

2. A cistern according to Claim 1 in which the means to halt the discharge operates by breaking the syphonic action when the liquid within the cistern falls to a predetermined level.

3. A cistern according to Claim 2 in which the means to halt a discharge includes a valve in communication with the syphon and located at the predetermined level, and pneumatic means which cause the valve to open when actuated by operation of the second discharge-initiating device.

4. A cistern according to Claim 3 in which the pneumatic means comprises bellows which extend when actuated.

5. A cistern according to Claim 4 in which the pneumatic means also include a pneumatic device which, when itself activated by operation of the second discharge-initiating device, activates the bellows.

6. A cistern according to Claim 3 in which the pneumatic means include a timing mechanism which causes it, once actuated, to hold the valve open for longer than the time it takes for the cistern to empty, but shorter than it takes for the cistern both to empty and to refill again.

7. A cistern according to Claim 6 in which the timing mechanism is in the form of an air bleed.

8. A cistern according to Claim 3 in which the valve is a flexible flap valve.

9. A cistern according to Claim 1 in which operation of each of the first and second devices initiates a discharge by pneumatically breaking an airlock within the cistern, so allowing the start of the syphonic action which the airlock had previously prevented.

10. A cistern according to Claim 9 in which operation of both of the first and second devices compresses a common bellows, so discharging air from it and using the discharge to break the airlock.

11. A cistern according to Claim 9 in which the first and second devices are in the form of buttons, depression of which squeezes bellows.

12. A water closet, fitted with a cistern according to any of the preceding claims.

Amendments to the claims have been filed as follows 1. A cistern for a WC or the like, including first and second devices to initiate a discharge of the vessel by syphonic action, in which operation of the first such device initiates a discharge which continues until the cistern is substantially empty, whereas operation of the second such device both Initiates a discharge and actuates means to halt that discharge before the cistern is substantially empty.

2. A cistern according to Claim 1 in which the means to halt the discharge operates by breaking the syphonic action when the liquid within the cistern falls to a predetermined level.

3. A cistern according to Claim 2 in which the means to halt a discharge includes a valve in communication with the syphon and located at the predetermined level, and pneumatic means which cause the valve to open when actuated by operation of the second discharge-initiating device.

4. A cistern according to Claim 3 in which the pneumatic means comprises bellows which extend when actuated.

5. A cistern according to Claim 4 in which the pneumatic means also include a pneumatic device which, when itself activated by operation of the second discharge-initiating device, activates the bellows.

6. A cistern according to Claim 3 in which the pneumatic means include a timing mechanism which causes it, once actuated, to hold the valve open for longer than the time it takes for the cistern to empty, but shorter than it takes for the cistern both to empty and to refill again.

7. A cistern according to Claim 6 in which the timing mechanism is in the form of an air bleed.

8. A cistern according to Claim 3 in which the valve is a flexible flap valve.

9. A cistern according to Claim 1 in which operation of each of the first and second devices initiates a discharge by pneumatically breaking an airlock within the cistern, so allowing the start of the syphonic action which the airlock had previously prevented.

10. A cistern according to Claim 9 in which operation of both of the first and second devices compresses a common bellows, so discharging air from it and using the discharge to break the airlock.

11. A cistern according to Claim 9 in which the first and second devices are in the form of buttons, depression of which squeezes bellows.

12. A water closet, fitted with a cistern according to any of the preceding claims.

13. A cistern according to Claim 1, substantially as described with reference to the accompany drawings.