AP8A

AP8A - Lavatory cistern.

Info

Publication number: AP8A
Application number: APAP/P/1986/000032A
Authority: AP
Inventors: Gosta Hammarstedt
Original assignee: Arcu Armaturind; Ifoe Sanitaer Ab
Priority date: 1985-04-04
Filing date: 1986-04-01
Publication date: 1988-01-04
Also published as: GB2173525B; IN164102B; MX164576B; AP8600032A0; CN86101333A; GB2173525A; GB8508973D0; BR8601477A; CN1007278B

Abstract

A lavatory cistern which provides a rapid discharge of a predetermined

Description

Lavator£_Cistern_x

This invention relates to two part lavatory cisterns adapted to discharge rapidly a fixed quantity of flushing water from a metering portion supplied from a larger storage portion.

In countries and areas where mains water supplies are inadequate or lacking there is a need for a simple device 10 which will provide efficient water flush cleansing for wash basins and water closets. Such devices must be able both water and to discharge a series of flushes before for refilling. In most cases water will be supplied from buckets so that the cistern must be able to 15 withstand sudden inrushes of water when being refilled.

The flushing system must be economical in the amount of water used so that many flushes can be obtained before the cistern needs refilling.

to store the need

Two part lavatory cisterns have been proposed for use in railway carriages, for instance in United Kingdom patent 19,021 of 1897, and for use in country areas, for instance in United Kingdom patent 297,299. These cisterns are designed to be constructed from metal components and include complex water release valves which are expensive to manufacture. The reliability of those systems which have been produced has been poor. Flushing time has tended to be slow causing inadequate removal of faeces, etc. so that the operator has tended to use multiple flushes negating the objective to conserve water. With the advances in water supply services in the more technologically developed areas of the world no development has taken place in this field for many years.

The object of the present invention is to provide an improved lavatory cistern which is reliable, inexpensive to manufacture and provides a series of rapid water discharges

BAD ORIGINAL before refilling. A further object is to provide a cistern which economises the use of water and is ideally adapted for use in countries and areas where water is scarce. Another object is to provide a cistern which can be easily filled using buckets and similar containers.

These and other objects of the invention are achieved according to the present invention by means of a lavatory cistern having a major storage tank and an interconnected minor flush tank, and containing externally operated valve means which allow the rapid discharge of the contents of the flush tank through an exit pipe, characterized in that, while flushing, said valve means is adapted for vertical movement to uncover the exit pipe with a first part, meanwhile a second part of said valve means is urged against holes in the partition between the storage tank and the flush tank to prevent ingress of water therefrom when said valve means is raised.

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Lavatory cisterns according to the invention are able to store 5 to 30 or so litres of water and rapidly discharge from 1 to 3 liters of water at each flush. When filled the cistern will be able to provide from 10 to 20 or more flushes before replenishment. The rapid discharge is ensured by using a simple but efficient valve mechanism to cover a large diameter outlet pipe. Discharge takes place when a manually operated plunger is raised and the water flows out of the flush tank under the action of gravity. Air inlet means ensure that air flows rapidly into the flush tank as the water discharges. The flush tank is refilled from the storage tank through interconnecting flow holes which are closed by the valve mechanism while the discharge plunger is operated. The quantity of water discharged at each flush and its force is independant of the amount of water in the storage tank.

Due to the design of the lavatory cistern according to the invention it can be easily manufactured using synthetic polymers by conventional mass production methods. The choice of materials for fabricating the components of the lavatory cistern is dependant upon the method of

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-3manufacture chosen. Preferably the materials from which they are made must be capable of withstanding chemical sterilisation treatments. In general most thermoplastic synthetic polymers are suitable such as polystyrene, polyolefins, polyvinyl esters, polyvinylacetals, polycarbonates, cellulose esters, polyamides, acrylic polymers and copolymers such as ABS. Other materials that may be used for fabricating some or all of the components of the lavatory cistern include laquered, stainless or enamelled sheet metal, cast-iron, aluminium, sanitary porcelain, fire-clay or wood.

The major components can be made by the vacuum forming process using a sheet of thermoplastic material such as polystyrene. Alternatively the injection moulding process can be used to form the major components using a thermoplastic resin such as polypropylene. The synthetic polymers used in either method of manufacture can be pigmented and contain other additives, such as stabilisers, according to conventional practice. Where small numbers are involved the cistern receptacle and other components may be made from low temperature curing resins such as unsaturated polyester and epoxy resins reinforced with glassorotherfibre.

The invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a vertical cross section of one embodiment of the lavatory cistern according to the invention,

Figure 2 is a side view of the right side of the embodiment shown in Figure 1,

Figure 3 is a top plan view of the cistern receptacle shown in Figure 1,

Figure 4 is a top plan view of the partition element of the cistern shown in Figure 1

Figure 5 is an inverted plan view of the cover plate used in the embodiment of Figure 1

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Figure 6 is a vertical cross section of a second embodiment of a lavatory cistern according to the invention,

Figure 7 is a side view of the right side of the embodiment shown in Figure 5 ,

Figure 8 is a top plan view of the partition element of the cistern shown in Figure 6,

Figure 9 is a top plan view of the cover plate used in the embodiment of Figure 6 ,

Figure 10 is a vertical cross section of a third embodiment of a lavatory cistern according to the invention,

Figure 11 is a vertical cross section of a fourth embodiment of a lavatory cistern according to the invention, and

Figures 12 to 21 are cross sections of alternative valve systems for use in the lavatory cistern according to the invention.

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In the first embodiment of the invention described the major components are intended to be fabricated from a thermoplastic polymer, preferably polypropylene, polyethylene or ABS, by injection moulding.

A receptacle 3, see Figure 1, has a vertical rear wall 4, two downwardly converging side walls 5 and 6, see Figure 2, and a converging front wall 7. The lower portion of the receptacle 3 is recessed on both sides by bottom parts 8 and 9 extending horizontally towards each other from the side walls 5 and 6. The bottom parts 8 and 9 each have a length about one quarter of the width of the receptacle 3 so that it is divided into an upper storage tank 10, and a lower flush chamber 11. The volume of the flush chamber 11 is defined by the lower part of the rear wall 4, the substantially recessed continuations 5' and 6' of the side walls 5 and 6, the slightly recessed continuation of the front wall 7 and the base 12. The base 12 is slightly inclined downwards from the walls towards the centre. At the centre there is an exit hole and outlet pipe 13 which

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-5is moulded integrally with the receptacle 3 and is adapted to fit into a flush pipe 14, see Figure 2.

The section of the flush pipe 14 immediately below the outlet pipe 13 preferably contains a venturi sleeve, not shewn, which improves the rate of flow of the flushing water when it leaves the flush chamber 11.

The flush chamber 11 is divided from the storage tank 10 by means of a loose fitting partition plate 15. The construction of the plate 15 is shown in greater detail in Figure 4 . The partition plate 15 is constituted by a flat rectangular plate 16 with smoothly rounded corners. The upper surface of the plate 16 has a thin flexible flange 17 along the edge. The flange 17 is preferably about 0.2 mm thick and at least 2 mm wide. The flange 17 forms an easily deflected sealing lip which ensures a sufficiently good seal when the plate 16 is pressed into engagement with the walls 4, 5, 6 and 7 against a ridge or seat 18. Some leakage between the storage tank 10 and the flush chamber 11 is permissible and does not impair the operation of the cistern. This method of manufacture avoids the need for close tolerances on the dimensions of the receptacle 3 and the plate 15.

The seat 18 is formed partly by a horizontal shoulder 19 between the front wall 7 and its lower recessed part 7' and partly by similar shoulders 20 and 21 between the bottom parts 8 and 9 on the one side and the wall continuations 5' and 6' on the other. Ribs 22 project into the flush chamber 11 from the rear wall 4 and the base 12. The ribs 22 are parallel to each other and equidistant. The ribs 22 are preferably bevelled upwardly so as to form a support for the base 12. The upper edge of the ribs 22 ends on the same horizontal level as the shoulders 19, 20 and 21 in order to form additional support for the plate 16. The

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-6ribs 22 serve many purposes apart from those described.

They reinforce the sides of the receptacle 3 so that it is able to maintain its shape under stress, e.g. when 10 to 30 litres of water is poured rapidly into the storage portion. The ribs 22 also assist in directing the flow of the water from the flush chamber 11 into the outlet pipe 13.

The various recesses and shoulders moulded into the receptacle 3 generally assist in strengthening the structure so that thinner walls may be used than without this reinforcement and less moulding polymer used overall. The various converging or inclined surfaces also assist in this purpose so that a substantial amount of water can be stored without distortion or rupture.

The difference in height between the upper surface of the shoulders 2 0, 21 and the adjacent bottom parts 8 and 9 is preferably about 7 mm while the thickness of the plate 16 is preferably about 3 mm. These dimensions ensure that the flange 17 in this region may be deflected to abut the vertical part of the shoulders 20 and 21. The plate 16 also abuts the rear wall 4 and the front wall 7 providing an excellent seal. From their shape it will be seen that while the flanges 17 are deflected upwards when the plate 16 is pressed downwards they wilt engage the wall surface in a manner which will resist upward movement. As can be seen from Figure 3 the seat formed by the shoulders has rounded corners which match those of the plate 16.

The receptacle 3 is preferably suspended by two special suspension profiles 23 and 24, see Figure 2, having the shape of a flat U in cross section and projecting above the upper and below the lower side of the storage tank 10. Each suspension profile has a fixing hole 25 for the insertion of a screw, hook or other fastening device. The profiles are moulded integrally with the rear wall 4 of the receptacle 3 and as well as providing suspending means they bad original .li

-7reinforce the wall 4. The downwardly projecting profile ends are interrupted by the bottom parts 8 and 9 but this causes no problem when the receptacle is manufactured by injection moulding.

In accordance with a preferred embodiment of the invention, the main or intermediate part of the suspension profiles is formed with an

Ή' cross section.

The shanks of the H' facing rearwardly, are shorter than the shanks located 10 inside the storage tank. The end portions of the suspension profiles do not show the shorter shanks which are filled in to increase their strength and ability to take strain. The shorter shanks are not visible in Figure 3 due to the presence of a ledge 26 which extends around the upper edge of the receptacle 3.

The ledge 26 reinforces the upper part of the receptacle 3 and provides support for a cover plate 27. The plate 27 is preferably narrow, about 50 mm width, and acts as a guide and a support rather than a complete cover. The cover plate 27, see Figure 1, bridges the upper opening of the receptacle 3 and holds together the rear wall 4 and the front wall 7. For this purpose the ends of the base 28 are provided with protrusions 29 and 30 pointing downwards and abutting the rear wall 4 and front wall 7. The surface of the protrusion 29 is inclined to match the inclination of the wall 7. This protrusion houses a threaded brass insert 31 into which is turned a screw 32 through a hole 33 in the front wall 7.

The protrusion 30 is preferably a flat rim having holes 34, through which screws 35 may extend from the inside of the storage tank. These screws engage with nuts 36 fitted into recesses 37 in the outer surface of the rear wall 4.

The wall 4 is thicker at the edge where the recesses 37 are located. Each recess includes a hole 38 through the wall for the passage of the threaded portion of the screw. The bad ORIGIN At

-810 cover plate 27 thus counteracts the expansion forces caused by the weight of water when the receptacle is full which otherwise would tend to push the walls 4 and 7 apart. The cover plate 27, see figure 5, carries an integral longitudinal beam 39 which is centrally located and continuous between the protrusions 29 and 30 except for where it is formed into a guide sleeve 40 the purpose of which will be described later. The upper surface of the plate 27 carries a rocker support 43, which is located at about half the distance between the protrusion 29 and the sleeve 40. The rocker support 43 is preferably I shaped when viewed from above the web extending crosswise in relation to the plate 27; see dashed portion in Figure 3. The flanges are bevelled as shown in Figure 1.

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The support 43 is intended to support a rocker arm 44, which preferably has an inverse U” shape, the middle part of its web 45, resting on the support 43 and the inside of its flanges 46 abutting the longitudinal edges of the cover plate 27. Thus a very simple and efficient means of mounting and guiding the rocker on the rocker support is achieved. The rear end of the rocker web is provided with a hole 47 through which extends the upper end of a flush bar 49 which terminates in a handle 48. The latter can be mounted upon mounting the rocker or it is possible to arrange the flush bar by inserting it, with its lowermost end first, through the rocker hole and the bearing.

The partition bottom 15, see Figure 4, has to withstand the mass of water above it in the storage tank 10 during periods of flushing and replenishment when it refills.

For this reason the upper surface of the partition bottom 15 carries ribs 50 which project perpendicularly and extend radially from a centrally located guide sleeve 51, to the edge flange 17. The ribs 50 are bevelled with their lowest point by the flange 17. The guide sleeve 51 encircles the flush bar 49 leaving an annular air space

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-9around it apart from a small bearing wall 52. The bearing wall 52 extends across the central channel of the sleeve 51 at approximately half its height. The bearing wall 52 has a central bore which serves to position the flush bar 49 centrally but allows it to slide in a vertical direction. The upper part of the guide sleeve 51 is formed as a recessed bore 54 for housing the lower end of a ventilation pipe 55. The ventilation pipe 55 extends vertically to the top of the receptacle 3 where it fits into the inside of guide sleeve 40 in the cover plate 27. The internal width of the pipe 55 is preferably at least double that of the diameter of the flush bar 49.

The flush bar 49, see Figure 1, is completely isolated from the interior of the tank 10 by the pipe 55 and is maintained in a coaxial position by the bearings 41 and 52. The ventilation pipe 55 communicates with the atmosphere at its upper end through ventilation cavities 42 within the guide sleeve 40 in the cover plate 27. The lower end of the ventilation pipe 55 communicates with the flush chamber 11 via an exhaust pipe 56. The pipe 56 extends outwardly from the interior of the guide sleeve 51 close to, but above, the guide sleeve 51 and slopes down to the edge of the partition 15 close to the rear wall 4. The pipe 56 terminates at the lower surface of the partition 15. The pipe 56 also serves as a reinforcing member for the partition plate 15. The bore of the exhaust pipe 55 is approximately the same as that of the pipe 55 with which it communicates. The ventilation system comprising the pipes 55 and 56 allows air to enter the flush chamber 11 during flushing and replace the water. After flushing the system allows air to leave the flush tank 11 as it refills. The particular configuration shown minimises the entry of water into the pipes 55 and 56 during flushing. This feature is most important as any such water will be projected out of the cavities 42 with some force during refilling. In the final stage of refilling, water will rise in pipes 55 and

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-1056 to the same level as in the storage tank, but there is r.o substantial push up any longer and water will not be thrown out of the pipe 55. What should be prevented is too early ingress of water into pipes 55 and 56 when the chamber 11 is being refilled.

The partition bottom 15 contains a number of flush holes 57 which, when unobstructed, allow water to flow into the flush chamber 11 from the storage tank 10. Each hole 57 is surrounded with a downwardly protruding collar 58. The holes 57 are located circumferentially about the guide sleeve 51 and between the ribs 50. In the preferred embodiment shown there are no flush holes between the two rear ribs under the exhaust pipe 56. Instead small bosses 60 are positioned along the circumference. The height of the bosses 60 and the collars 58 are the same. The total area of the holes 57 is such that the flush chamber 11 will be refilled in 5 to 60 seconds, preferably 10 to 15 seconds. From a functional point of view, a shorter refit time is preferred, but the longer a refill takes, the smaller the holes 57 and the easier to close them and keep them closed during flushing.

For control of the discharge and refilling of the flush chamber 11, a valve system is used. In the first embodiment the system comprises a valve disc 59 slidably mounted on the lower portion of the flush bar 49 where it extends below the partition 15 into the chamber 11. The upwards movement of the disc 59 is constrained by a stop ring 61 or similar device attached to the flush bar 49.

To ensure rigidity the lower surface of the disc 59 carries a sleeve or guide shaft 66. The lower end of the flush bar 49 is rigidly attached to a valve head 64. Between the lower surface of the disc 59 and the upper surface of the head 64 is a pressure spring 62. The spring 62 is retained by recess 65 in the upper surface of the valve head 54 and a groove 63 on the lower surface of the disc

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-1159. In order to ensure a good seal over the outlet pipe 13, the valve head 64 is held against the bottom of the chamber 12 by a further pressure spring 67. The pressure spring 67 is located around the flush bar 49 exerting pressure on the top of the valve disc 59 and a recess in the inside of the guide sleeve 51. As illustrated in other embodiments, it is possible to use gravity alone to hold the valve disc 64 against the outlet pipe 13.

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When it is i s

While the lavatory cistern according to the invention is filled with water and dormant the chamber 11 will be full of water and also the tank 10. The pressure of the spring 67 will hold the valve head 64 against the base 12 of the chamber 11 so that the outlet pipe is covered.

desired to release flushing water the rocker 44 depressed. The rocker 44 pivots about a fulcrum provided by the rocker support 43 and its further end engages the lower end of the handle 48 on the flush bar 49. Continued force on the rocker 44 raises the flush bar 49 and the associated valve head 64 causing the contents of the flush chamber 11 to flow rapidly, under the action of gravity, into the outlet pipe 13. While the water flows out of the chamber 11 it is replaced by an equivalent quantity of air which flows in from the outside atmosphere through the ventilation pipe 55 and the exhaust pipe 56.

The movement of the rocker 44 is restricted when its end reaches the surface of the cover plate 27. At this stage the upper surface of the valve disc 59 will be urged against the lower surface of the partition 15 obstructing the flush holes 57 and preventing the flow of water from the storage tank 10 into the flush chamber 11. The force on the lower surface of the valve disc 59 is provided by the upper surface of the valve head 64 via the spring 62.

When the rocker 44 is released the flush bar drops under the action of the spring 67 and the valve head 64 again

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-12covers the outlet pipe 13. The valve disc 59 will no longer obstruct the flush holes 5? and water will flow through them into the chamber 11 from the tank 10 under the action of gravity. The air in the chamber 11 will be 5 vented out by the same route as it entered through the pipe 50 and 55. The time taken to replenish the chamber 11 will depend upon the area of the holes 57 and the quantity of water in the tank 10.

In the second embodiment of the invention, see Figures 6 to 9, the cistern receptacle and other major components are intended to be fabricated from thermoplastic sheet, preferably high impact polystyrene, by the vacuum forming process. In many cases the component parts are similar and have been given the same reference numerals as those for the equivalent parts in the first embodiment.

The receptacle 3, see Figures 6 and 7, has a vertical rear wall 4, two downwardly converging side walls 5 and 6 and a converging front wall 7. The lower portion of the receptacle walls 5,6 and 7 converge at a greater angle at a line 75. A partition plate 76 which is located along the line 75 divides the receptacle 3 into an upper storage tank 10, and a Lower flush chamber 11. The volume of the flush chamber 11 is defined by the lower part of the rear wall 4 , the convergent portions 5', 6' and 7' of the walls 5, 6 and 7. The base 12 is slightly inclined downwards from the walls towards the centre. At the centre there is an exit hole and outlet pipe with integral flange 13 which is fitted into the exit hole. The outlet pipe 13 is adapted to fit into a flush pipe 14.

The flush chamber 11 is divided from the storage tank 10 by means of the partition plate 76. The construction of the plate 76 is shown in greater detail in Figure 8. A central support member 77 is fitted into the centre of the plate 76. The combination forms a flat r ec t a ng u IQp|£j|NAL (f

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-13with smoothly rounded corners. The plate 76 and support member 77 are preferably separate components to assist assembly and maintenance. The edge of the plate 76 is formed with a smooth bend which forms a good seal when the plate 76 is pressed into engagement with the walls 4, 5, 6 and 7 where the latter three converge sharply along the line 75. This method of manufacture avoids the need for close tolerances on the dimensions of the receptacle 3 and the plate 76. If necessary the seal may be strengthen ed by use of a suitable adhesive or ultra-sonic welding.

As the receptacle 3 in this embodiment is fabricated by vacuum forming there are no strengthening ribs. Rigidity is ensured by means of a cover 80, which has a rim which encloses the rim of the receptacle 3. The cover, see

Figure 9, has a large filling aperture 81, which allows the contents of buckets and similar containers to be tipped into the cistern. The central portion of the cover 80 has the rocker support 43 formed into it. Two caps 83 and 84 are formed into the cover 80 to retain a ventilation pipe 68 and a protecting tube 72, for the flush bar 49.

The rim of the cover 80 carries fixing holes 82 (one shown) which allows the cover to be fixed to the top of the receptacle 3 by means of aligned holes by any of the known fixing devices for sheet materials. In Figure 6 the front wall 7 is attached to the cover 80 by means of a screw 32 having an expanding rubber bush. The rear wall 4 is fixed using a screw turned into a threaded bracket. The latter is fixed to the rear wall 4 using, e.g. pop-rivets.

The cover 80 carries the support 43 which acts as a fulcrum for the rocker arm 44, which may be the same as that described with reference to the first embodiment. The rear end of the rocker web is provided, in the manner previously described, with the hole 47 through which extends the upper end of the flush bar 49 which terminates bad original

-14i n the handle 48.

The section of the flush pipe 14 immediately below the outlet pipe 86 contains a venturi sleeve 87 which improves the rate of flow of the flushing water when it leaves the flush chamber 11.

The operation of the second embodiment of the invention is substantially the same as that described with respect to the first embodiment using a similar valve system. In the dormant condition the spring 67 holds valve head 64 against the outlet pipe 13. Depressing the rocker arm 44 initiates the release of flush water from the chamber 11. After the rocker 44 is released the chamber 11 refills from the reservoir of water in the storage tank 10. The differences between the two embodiments are related to the different routes taken by the air which enters and is vented from the chamber 11.

When water flows out of the chamber 11 in the second embodiment it is replaced by an equivalent amount of air which flows in from the outside atmosphere through the ventilation pipe 68. When the chamber 11 refills the air is vented out through the same pipe 68.

In a third embodiment, see Figure 10, the cistern receptacle 3 comprises an upper storage tank 10 with a lower flush chamber 11 attached to its base. In the centre of the base of the attached chamber 11 is an exit hole and outlet pipe 13. The outlet pipe 13 is connected to the flush pipe 14 which, as described with reference to previous embodiments, may contain a venturi sleeve. The outlet 13 is normally held closed by the valve head 64 which is urged downwards by the mass of the water and the rod 49. The flush rod 49 extends upwardly through the base of the storage tank 10 through the ventilation pipe 55 to its handle 48. The rod 49 is maintained in a vertical

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-1 5position by the pipe 55 and, optionally, by one or more guide sleeves.

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When the handle 48 is raised, the outlet pipe 13 ceases to 5 be obstructed and the water in the chamber 11 flows out rapidly. The volume of water flowing out is replaced by an equivalent amount of air through the ventilation pipe 55. Water begins to flow into the chamber 11 from the storage tank 10 through the flush holes 57. The holes 57 have a small diameter and do not contribute appreciably to the flush discharge. When the handle 48 is released the continuing flow of water through the holes 57 refills the chamber 11 and the displaced air flows out through the pipe 55 .

In a further embodiment, see Figure 11, the cistern receptacle 3 is divided into the storage tank 10 and the flush chamber 11 by the rectangular plate 16. The plate 16 rests on a seat 18 fixed to the side walls 5 and 6.

Functionally this embodiment operates in the same manner as the previous one.

A number of different valve systems may be used with each of the four described embodiments to control the discharge and replenishment of the flush chamber 11. The simplest system, described with reference to figures 11 and 12, relies on gravity alone to maintain the valve head 64 against the outlet pipe 13.

A double valve system, see Figures 12 and 13, uses gravity to hold the valve head 64 against the outlet pipe 13 in the dormant condition. The valve disc 59, slidably mounted on the lower portion of the flush bar 49, is held against the stop ring 61 by the pressure spring 62. When the rod 49 is raised, see Figure 13, the upper surface of the valve head 64 increases pressure on the spring 62 and the stop ring 61 enters the pipe 55. The upper surface of the disc bad original

-1659 covers the holes 57 and prevents water flow ing into the flush chamber during a flush discharge.

A similar valve system, see Figure 14, uses a balloon valve 5 formed by an oblate spheroid of resilient material 74.

The rod 49 enters the balloon through an aperture 78 in its upper surface and is attached to the inside lower surface. In the dormant state the balloon covers the outlet pipe 13 and is forced against it due to the mass of the rod 49.

When the flush rod 49 is raised, see Figure 15, the upper surface of the balloon engages the bottom of the plate 16 and deforms to cover the holes 57.

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A valve system in which the valve head 64 is held against the outlet pipe 13 by spring force, see Figure 16, uses a pressure spring 67 which surrounds the rod 49. The spring 67 exerts pressure between the bottom of the plate 16 and the top of the valve head 64. When the bar 49 is raised, see Figure 17, the upper surface of the valve head presses against the ends of tubes 79 which extend downwardly from the holes 57. As long as the upwards force is maintained water cannot flow into the chamber 11 through the holes 57.

The balloon valve system described with reference to Figure 25 14 can be combined with a pressure spring 67, see Figure

18. The lower surface of the balloon 74 is held against the outlet hole 13 by the force of the spring acting on the inside of the balloon 74 and the plate 16. When the bar 49 is raised, see Figure 19, water is released from the chamber 11 and the holes 57 are covered as descibed earlier.

A double spring valve system, see Figure 20, uses a pair of pressure springs 62 and 67. The slidable valve disc 59 is located between the two springs whose opposite ends act against the plate 16 and the upper surface of the valve head 64. In the dormant condition the combined action of

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-17the two springs 62 and 67 urge the valve head against the outlet 13. When the rod 49 is raised, see Figure 21, the upwards pressure -from the upper surface of the valve head 64 is transmitted through the spring 62 to the lower surface of the disc 59. The disc 59 covers the ends of the tubes 79 preventing water from flowing through them.

The invention is not restricted to the described and illustrated embodiments, and modifications can be made within the scope of the invention as defined in the following claims.

Claims

1. A lavatory cistern providing rapid discharge of predetermined amounts of water comprising a major storage tank and an interconnected minor flush tank, containing externally operated valve means which allow the rapid discharge of the contents of the flush tank through an exit pipe, characterized in that, while flushing, said valve means is adapted for vertical movement to uncover the exit pipe with a first part, meanwhile a second part of said valve means is urged against holes in the partition between the storage tank and the flush tank to prevent ingress of water therefrom when said valve means is raised.

2. A lavatory cistern as claimed in claim 1 characterized in that it is made from a thermoplastic polymer, preferably polyethene, polypropene or ABS and is fabricated by injection moulding.

3. A lavatory cistern as claimed in claim 1 and 2 characterized in that the side walls and the front wall converge downward and that the lower portion of the walls converges at a greater angle and the partition abuts the walls at the line where convergence changes.

4. A lavatory cistern as claimed in claim 1, characterized in that said first part is a valve head and said second part is a disc, pressure spring means being provided between these parts and/or between said disc and the partition.

5. A lavatory cistern as claimed in claim 4 characteri zed in that the valve head is connected to a flush bar adapted for vertical movement and extending through the tanks to the top of the receptacle.

6. A lavatory cistern as claimed in claim 5 characterized in that the disc is slidably mounted on the flush bar.

7. A lavatory cistern as claimed in any of the preceding claims characterized in that ventilation means allows air to enter and leave the flush tank from the surrounding atmosphere, the ventilation means being a pipe extending from the flush tank through the storage tar^ to the too of the receptacle. 'BAD ORIGINAL

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2. A lavatory cistern as claimed in claims 5 and 7 character!zee in tnat the flush bar is coaxially aligned within the ventilation pipe, and that the flush bar is movable up and down in a vertical direction by means of a lever.

9. A lavatory cistern as claimed in claim 8 characterized in that the lever consists of a rocker bar pivoting about a rocker support carried by a cover plate on the receptacle, the rocker support being formed integrally with the cover plate.