GB2275483A - Variable-flush facility for syphonic-discharge flushing cistern - Google Patents

Abstract

A syphon for a flushing lavatory cistern has an inlet end (2) and an outlet end (1), the inlet end (2), in use, communicating with the interior of the cistern. A vertically extending arcuate slot (4) is provided in the sidewall of the syphon at the inlet end (2) which is closable by means of a rotatable closure disc (9) pivotally mounted on the sidewall of the syphon. The closure disc includes an off-centre hole which may be brought into registry with different portions of the slot (4) in the sidewall, whereby the flushing volume of the a cistern in which the syphon is mounted may be varied. <IMAGE>

Description

VARIABLE FLUSH LAVATORY BYPHON The present invention relates to syphons for flushable lavatory cisterns.

Conventional syphons for use in flushing cisterns comprise an inverted "U" tube with two limbs, one being formed into a "bell" shape. Alternatively, these syphons can consist of an upstanding tube with a movable bell member positioned over it. In each case one end of the syphon (the "bell" end) communicates with the interior of the cistern while the other end leads to the bowl of a WC where it is desired that flushing water should be directed when a flush is initiated. In the case of a coaxial tube and bell, a flush is initiated by raising the bell, whereas in the case of a "U" tube, a diaphragm is provided in the bell which is moved upwardly to initiate a flush.

In each case, the flush ends when the syphonage action is broken by the descending water level in the cistern reaching the open end of the bell, allowing air to enter the syphon.

Dual flush syphons are known in which an aperture is provided at the top of the bell which causes premature termination of the syphoning action. The aperture may be blocked by some means accessible from the exterior of the system, such as by holding the flushing handle down to cause a projection on the diaphragm (in a "U" syphon) to block the aperture, resulting in a "full" flush. It is also known to provide a syphon which is convertible to dual or single flush capability by means of a resilient plastics plug which fits into the aperture. If the plug is fitted, the syphon behaves like a single flush syphon.

Recently, changes in the Water Byelaws in the United Kingdom have meant that requirements for maximum flushing volumes of lavatory cisterns now vary. It has therefore become desirable to be able to supply a cistern and in particular a syphon for a cistern whose maximum flush volume is variable.

It has recently been proposed (in GB2213846) to provide a single or dual flush syphon with an aperture in the sidewall of the bell which is sealable by a resilient plastics plug. Thereby, the maximum flushing volume is selectable between two values, depending upon whether the plug is in place or not. It has also been proposed to provide a number of such sealable holes.

GB2213846 also mentions the possibility of an aperture with a movable shutter, providing in effect an aperture of continuously variable height which would provide a continuously variable flushing volume. GB2213846 does not specifically disclose how to achieve this, but hints that the shutter would be vertically linearly slidable.

Clearly, it is desirable to provide an infinitely variable flushing volume, or at least a flushing volume which is selectable between a number of values. For example, it is not known what new regulations regarding maximum permitted flushing volume may be introduced in the future, and it would be desirable for manufacturers not to have to change the design of syphon, with associated tooling costs, every time the regulations are changed. Furthermore, a syphon with an infinitely variable height aperture could be adjusted to suit a number of different sizes and shapes of cistern which would contain different amounts of water when filled to a given level.

However, it is clearly somewhat more complex to provide a variable aperture than to provide a single aperture with a plug. In particular, a vertically slidable shutter would be complex to incorporate into a syphon, requiring guides in which the movable shutter is to run, and some means for creating a seal between the shutter and the syphon.

According to the present invention, a lavatory syphon for installation in a flushing lavatory cistern includes an inlet end, which, in use, communicates with the interior of the cistern, and an outlet end which communicates, in use, with a lavatory bowl, the inlet end being provided with an aperture in its sidewall adjacent to which a closure member is pivotally mounted so as to be movable across the aperture into a position in which it defines, with the aperture, a path of communication between the interior of the syphon and its surroundings, the level at which the said path communicates with the surroundings being variable by rotation of the closure member with respect to the sidewall of the syphon.

Thus, a syphon is provided in which the flushing volume, when the syphon is installed in a cistern, is easily varied by manually rotating the closure member. The level at which the path of communication between the interior of - the syphon and the exterior meets the surroundings will determine at what stage the flushing action terminates; when the descending water level in the cistern reaches the level at which the communication path opens into the interior of the cistern, air will enter the interior of the syphon via the communication path, thus terminating the syphoning action.

It should be understood that the term "aperture" embraces a hole in the side of the syphon or a cut-away portion of the lower rim of the inlet end of the syphon (i.e. the end which is open to the interior of the cistern, in use).

It should be understood that a syphon is always, in use, oriented in a particular way, that is to say with the "U" bend uppermost and the open ends facing downwards. Terms in this specification and in the claims such as "up", "down", "level", "height", etc in relation to a syphon should be construed accordingly.

It will be understood that pivotal mounting of the closure member is considerably simpler than mounting the closure member to be linearly slidable; fastening of the closure member to the sidewall of the syphon need be effected at only one point, and it is easy to make this attachment secure. It is also easier to operate a rotating closure member than a linearly sliding one.

It would be possible for the aperture to be surrounded by a flange or boss projecting from the sidewall of the inlet end of the syphon, and the closure member bearing against the flange to form a seal. However, in the preferred embodiment, the aperture is formed in a portion of the syphon sidewall having a substantially planar outer surface, against which the closure member bears to form the seal.

This simple and cheap arrangement provides a sufficiently effective seal between the closure member and the syphon body substantially to prevent the premature ingress of air into the syphon when the descending water level in the cistern passes the closure member.

In one embodiment, the closure member is provided with an aperture off-set from the centre of rotation of the closure member and arranged to be brought into registry with the aperture in the syphon by rotation of the closure member. In this event, the aperture in the syphon is preferably an arcuate slot which, in the embodiment, is part-circular with its centre of curvature coincident with the centre of rotation of the closure member.

Preferably the closure member is biassed against the flange.

It has been found that a simple and effective way of mounting the closure member is by means of a resilient spigot on the closure member engaging in a recess or aperture in the syphon sidewall (or vice versa). An interference fit between the spigot and recess/aperture may retain and possibly also biass the closure against the sidewall to form the seal. The spigot may be a separate member or may be integrally moulded with the closure member or syphon sidewall.

A calibrated scale could be provided on the closure member or sidewall of the syphon which would indicate, for a given shape and size of cistern, the flushing volume associated with given positions of the closure member.

The syphon, including closure member, is preferably made from polypropylene but could be made from other suitable material such as another plastics material.

In an alternative embodiment, the closure member at least partially defines a channel communicating between the aperture in the sidewall of the syphon and the surroundings, the level at which the channel communicates with the surroundings being movable by rotation of the closure member.

This arrangement would be desirable if, e.g. it were not desired to make a large hole in the sidewall of the syphon.

A specific embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a side view of the syphon in accordance with the invention; Figure 2 is a scrap section on the line X-X in Figure 1 on an enlarged scale; and Figure 3 is a view similar to Figure 2 of an alternative embodiment of the invention.

Referring to Figure 1, an inverted "U" shaped syphon comprises an outlet end 1 and a flared inlet end or bell 2. When the syphon is installed in the cistern of a WC, the outlet end 1 will pass through the floor of the cistern and be connected to the bowl of the WC. The bell remains in the cistern and thus the downwardly directed opening 3 defined by the bell communicates with the interior of the cistern.

Formed in a slightly raised portion 14 of the sidewall of the bell is a part-circular slot 4. At the centre of curvature of the slot 4 is a circular aperture 11 in the sidewall.

The syphon body is moulded as a single unit from plastics material, e.g. polypropylene.

Rotatably mounted on the sidewall is a closure disc 9 having an off-centre aperture 10. The aperture 10 is located at the same radius from the circular aperture 11 in the sidewall as the slot 4.

The closure disc is of plastics, e.g. polypropylene, and also has a central aperture 12. It is mounted on the syphon sidewall by means of a resilient plastics spigot 13 (e.g. of polypropylene) which is moulded as a separate unit, although it could be formed integrally with the syphon wall or the closure. The spigot 13 is an interference fit in the central aperture in the closure and in the circular aperture 11 in the sidewall.

This-arrangement has the advantage of simply and securely retaining the closure 9 against the syphon sidewall, and also to a certain extent biassing the closure 9 against the sidewall. A seal is provided between the interior plane face of the disc and the plane surface of the raised portion 14 of the sidewall. The interference fit provides resistance against turning the closure disc 9 and thereby ensures that the disc 9 remains at whatever position it is moved to.

Referring to Figure 3, in an alternative arrangement, a spigot 6 projecting from the sidewall or closure disc could be provided with an enlarged head portion 8 and a reduced diameter portion 7 by means of which the spigot 6 is a snap fit in an aperture in the closure or sidewall, respectively. Figure 3 also shows an alternative arrangement for the seal, i.e. the closure disc bearing against a flange 5 projecting from the sidewall and extending around the periphery of the arcuate slot 4. In another alternative arrangement, the disc could be retained by means of a clip, e.g. a steel "star washer" with teeth around its inner circumference which bite into the spigot. Alternatively, the end of the spigot could be provided with an annular groove into which a "C" clip is received.

In the alternative embodiments described with reference to Figure 3, the disc is made of polypropylene and is pressed against the flange 5 by virtue of its resilience to form a seal, the centre of the disc being retained at a position slightly further inwards towards the sidewall of the bell than the outermost extent of the flange 5.

In use, the aperture 10 in the disc 9 may be brought into and out of registry with the slot 4 by manually rotating the disc 9. When the aperture 10 is completely out of registry with the slot 4, e.g. if the disc were to be rotated, say, 90' clockwise from the position shown in Figure 1, the slot 4 is completely sealed. When a flush is initiated, the syphon action is only terminated when the descending water level in the cistern reaches the bottom of the bell, at which point air enters the syphon and breaks the syphoning action.

When the disc 9 is in the position shown in the figures, i.e. when the aperture 10 is in registry with the upper end of the slot 4, the syphoning action will terminate when the descending water level in the cistern reaches the level "L" in Figure 1 and air is allowed into the syphon. Clearly, the volume of the flush in this case is considerably reduced from the case where the slot 4 is completely closed-off by the disc 9. Intermediate flushing volumes may be provided by rotating the disc to vary the height of the aperture 10. The height of the aperture determines the point at which the syphoning action ceases, provided the aperture is in registry with the slot.

An infinitely variable flush volume is thus provided, within limits. It is envisaged however, that "click stops" could be provided according to well known means, such as interlocking projections and detents on the disc and bell sidewall, e.g. on the right hand side of the disc in Figure 1. The click stops would of course correspond to specific flushing volumes for a given size and shape of cistern, given that the syphon is installed at a particular height in the cistern.

It is also envisaged that a calibrated scale or markings could be provided on the bell sidewall and/or disc to indicate the flushing volume corresponding to particular positions of the disc or to indicate which positions of the disc will result in a given flushing volume for different models of cistern.

In an alternative embodiment, not shown in the drawings, the disc itself could define the upper and lower limits of the variable range of flushing volumes. A smaller circular aperture could be provided in the sidewall of the bell 2. The disc could be provided with a flange similar to the flange 5 in Figure 3 except that the flange would project inwardly towards the sidewall and would have a cut-away portion at its lower end. The flange, disc and bell sidewall would then define an arcuate channel communicating with the aperture in the bell sidewall.

The cut-away portion of the flange would allow air to enter the channel and thus the level of the cut-away portion would determine when the flush is terminated.

The level of the cut-away portion is of course varied by rotating the disc.

Alternatively, the disc could be provided with a flange extending around its circumference, with a cut-away portion at one point on the circumference. The position of the aperture in the sidewall would then be immaterial, so long as it was covered by the disc. A flow path would again be defined between the aperture in the bell and the cut-away portion of the circumferential flange, the flow path occupying the whole area covered by the disc.

Rotation of the disc would. again determine the flushing volume, by altering the level of the cut-away portion.

Claims (16)

1. A syphon for installation in a flushing lavatory cistern comprising an inlet end which, in use, communicates with the interior of the cistern and an outlet end which communicates, in use, with a lavatory bowl, the inlet end being provided with an aperture in its sidewall adjacent to which a closure member is pivotally mounted so as to be movable across the aperture into a position in which it defines, with the aperture, a path of communication between the interior of the syphon and its surroundings, the level at which the said path communicates with the surroundings being variable by rotation of the closure member with respect to the sidewall of the syphon.

2. A syphon as claimed in Claim 1 wherein the aperture is formed in a portion of the syphon sidewall having a substantially planar outer surface against which the closure member bears to form a seal.

3. A syphon as claimed in Claim 1, wherein the aperture is surrounded by a flange projecting from the sidewall of the syphon and the closure member bears against the flange to form a seal.

4. A syphon as claimed in any of the preceding claims wherein the closure member has an off-centre aperture arranged to be brought into registry with the aperture in the sidewall of the syphon by rotation of the closure member.

5. A syphon as claimed in Claim 4 wherein the aperture in the sidewall is constituted by an arcuate slot.

6. A syphon as claimed in Claim 5 wherein the slot is part-circular, the centre of curvature being substantially coincident with the centre of rotation of the closure member.

7. A syphon as claimed in any preceding claim in which the closure member is biassed against the sidewall.

8. A syphon as claimed in any preceding claim in which the closure member is pivotally mounted by means of a spigot projecting from one of the closure member and the syphon sidewall engaging in a circular aperture or recess in the other of the closure member or syphon sidewall.

9. A syphon as claimed in Claim 8 in which the spigot is an interference fit in the said circular aperture or recess whereby the closure member is retained against the syphon sidewall.

10. A syphon as claimed in Claim 8 or Claim 9 wherein the spigot is moulded as a separate member.

11. A syphon as claimed in any preceding claim including a calibrated marking or markings on the sidewall and/or closure member indicative of the flushing volume provided by the syphon at particular positions of the closure member when it is installed in a given size and shape of cistern.

12. A syphon as claimed in any preceding claim comprising plastics material.

13. A syphon as claimed Claim 12 comprising polypropylene.

14. A syphon as claimed in Claim 1 wherein the closure member at least partially defines a channel which communicates between the aperture in the sidewall of the syphon and the surroundings, the level at which the channel communicates with the surroundings being movable by rotation of the closure member.

15. A cistern including a syphon as claimed in any preceding claim.

16. A lavatory syphon substantially as specifically herein described with reference to the accompanying drawings.