METHOD AND SYSTEM FOR DISCHARGING A WASTE STREAM FROM A TOILET AND SIPHON INSTALLATION FOR USE THEREWITH

The invention relates to a method for discharging a waste flow which consists of liquid and solid parts and comes from the flushing of a toilet, wherein the waste flow is accelerated at least once. Such a method is known, for instance from the international patent publication WO 98/03743 of applicant.

Particularly in situations where a toilet is flushed with a relatively small amount of water, as is the case in a modern, water-saving toilet having a cistern of small volume, the speed of the waste flow is often not sufficient to transport the solid parts over the full length of the discharge pipe into the sewer system. The consequence hereof is that these solid parts are left somewhere in a relatively flat part of a discharge pipe, and there form an obstacle blocking the solid parts of subsequent flushes. This eventually brings about an accumulation which will result in blockage of the discharge pipe.

In order to prevent this it is therefore known to locally accelerate the waste flow consisting of liquid and solid parts. Use is often made for this purpose of a flow increaser or ^λ booster' through which the waste flow is guided. In this flow increaser the waste flow is temporarily stored in a tank of reservoir until, after several flushes, the level in the tank has risen so far that it overflows. A siphoning action then results whereby the waste flow is as it were ^λ sucked' out of the tank of the flow increaser. The waste flow hereby acquires a considerably greater speed than it had when leaving the cistern, so that the solid parts will be entrained over a greater distance, and the risk of blockage of the discharge pipes is thus reduced.

A drawback of the known method is that the flow increaser must be given a relatively voluminous form in order to ensure a sufficient capacity, and thus a sufficiently- great acceleration of the waste flow, and to also prevent blockage by solid parts which do after all remain for some time in the flow increaser. A flow increaser is for instance marketed at the moment by applicant under the name "Gustavsberg' s Water Saving System", which is intended to be incorporated in a shared discharge pipe of a number of households. This known flow increaser is provided with a relatively narrow but high tank which is so large that it is only suitable for application in high-rise projects.

In addition, as stated, a method of applicant is also known for discharging a waste flow which is described in WO 98/03743, and wherein use is made of a flow increaser with a relatively flat structure which is intended for installation in the crawl space of low-rise residential buildings. While this flow increaser is lower than the above described model, it is also wider so that a relatively large amount of space must also be left clear therefor. Furthermore, as a result of the low structure and the associated large surface area, special hydrodynamic measures are necessary in this flow increaser in order to ensure that an adequate siphoning action is still obtained when there is a small rise in the liquid level.

In addition to their large dimensions, both the known types of flow increaser have the drawback that their operation can be very adversely affected, particularly by fat residues which are for instance present in waste water- from bathrooms or kitchens. Such fat residues are deposited in the flow increaser when the waste flow is standing still therein and adhere strongly to all surfaces so that they are not readily flushed away. Such fat residues ultimately result in

(partial) clogging of the flow increaser, whereby the flow speed in the whole discharge system can become insufficient to ensure a reliable transport, particularly of the solid parts, to the sewage system. The invention now has for its object to provide a method of the above described type, wherein the stated drawbacks do not occur. According to the invention this is achieved in such a method in that the acceleration of the liquid takes place when it flows out of the toilet, or immediately thereafter. In this way it is possible to suffice with a very small amount of water to flush the toilet, because the transport function is already supported by the acceleration immediately upon leaving the toilet. The flow increaser can also be embodied very compactly since it only has to deal with the waste flow from the toilet. In addition, the risk of clogging of the flow increaser is considerably reduced because fat residues are no longer carried therethrough.

The waste flow is preferably accelerated by means of a siphoning operation, wherein the waste flow is collected and only accelerated after reaching a determined volume. Use can hereby be made for the acceleration of a simple system without moving parts which is operated by the waste flow itself. Furthermore, the effect of the acceleration is thus enhanced by accumulating the waste flow. This is particularly the case when the volume required for the acceleration is reached only after at least three successive flushes of the toilet. Using for instance a flush volume of only 2.5 litres, as used in a so-called Ultra-Low Flush Toilet (ULFT), a volume of 6 litres (the present standard) can thus still be achieved for the transport through the discharge pipes.

Prior to acceleration at least a part of the liquid is preferably separated from the waste flow, and only this

separated liquid is accelerated and fed back again to the waste flow. By guiding only that part of the waste flow which actually contributes toward the acceleration, i.e. the liquid, through the flow increaser, this flow increaser can be given a considerably more compact form. In addition, the response behaviour of the flow increaser is in this way improved because it will no longer be influenced by the presence of solid parts in the flow increaser, while the acceleration caused by the flow increaser moreover becomes reproducible.

The method according to the invention can be performed in a small space when the waste flow is discharged, when it flows out of the toilet or immediately thereafter, first in a substantially vertical path and, after a bend, in a substantially horizontal path, the separation and acceleration take place in the substantially vertical part of the path and the accelerated liquid is fed back in the substantially horizontal part of the path. The separation can be performed most effectively during a vertical movement of the waste flow, while the horizontal feedback ensures that the total. height of the path where the separation takes place remains limited.

The invention further relates to a system for discharging a waste flow which consists of liquid and solid parts and which comes from the flushing of a toilet adapted to perform the above described method. According to the present invention such a discharge system, which comprises at least one discharge pipe for the waste flow connecting to an outflow opening of the toilet and means connected to the discharge pipe for accelerating the waste flow, is characterized in that the accelerating means are situated at the position of or close to the outflow opening of the toilet.

The accelerating means herein preferably comprise a siphon installation which is adapted to collect the waste flow and which only becomes active for accelerating thereof once a determined volume has been reached. The volume at which the siphon installation becomes active can, as stated, advantageously amount to more than twice the flush volume of the toilet.

According to a preferred embodiment of the invention, the discharge system is provided with means placed between the discharge pipe and the siphon installation for separating out of the waste flow and feeding to the siphon installation at least a part of the liquid, and means connected to the siphon installation for feeding the accelerated liquid back again to the waste flow. The siphon installation is preferably provided with a feed opening connected to a standing part of the discharge pipe, and the separating means comprise an inflow edge at least partially bounding the feed opening and connecting smoothly onto a wall of the standing part of the discharge pipe. In this manner the liquid can be separated very easily, making use of the fact that the liquid will flow for the most part along the walls of the standing part of the discharge pipe, while the solid parts will usually drop downward through the middle of the pipe. In order to further minimize the space occupied, the siphon installation can be arranged to the side of the standing part of the discharge pipe.

For fitting purposes it is recommended here that the standing part of the discharge pipe and/or the siphon installation is formed integrally with the toilet. The toilet can thus be placed with a part of the discharge pipe and the siphon installation by a single fitter in one operation without further operations being necessary elsewhere in the

discharge system. This saves time and cost and moreover reduces the chance of errors.

In view of the limited space available in the vicinity of a toilet, the siphon installation is preferably given a relatively flat form and adapted to feed back the accelerated liquid to a lying part of the discharge pipe. The siphon installation can thus be built in under the toilet.

Finally, the invention further relates to a siphon installation for use in a discharge system as described above, and a combination of a toilet and a standing part of a discharge pipe and/or siphon installation formed integrally therewith.

The invention will now be elucidated on the basis of an embodiment, wherein reference is made to the accompanying drawing, in which:

Fig. 1 shows a section through a toilet with a part of a discharge system according to the invention connecting thereto,

Fig. 2 shows a section through a siphon installation applied in the discharge system of fig. 1, and

Fig. 3 and 4 are views corresponding with fig. 2 of the siphon installation during different stages of uses.

A toilet 1 comprises a toilet bowl 2, a cistern 4 connected thereto via a flush pipe 3 and a liquid trap 6 connecting to an outlet 5 of bowl 2. In the shown embodiment cistern 3 has a very small volume of for instance 2.5 litres, whereby toilet 1 can be characterized as an Ultra-Low Flush Toilet (ULFT) . Liquid trap 6 has an outflow opening 7 to which connects a system 8 for discharging a waste flow F coming from toilet 1. This waste flow F consists of liquid L and solid parts S. This discharge system 8 comprises a discharge pipe 9 with a standing part 10 and a lying part 11 (fig. 1).

The flush volume of toilet 1 is so small that only- bowl 2 can be cleaned herewith and the thereby created waste flow F can be transported through liquid trap 6. This volume is however wholly insufficient for the further transport of waste flow F through discharge pipe 9 to a sewer connection. Discharge system 8 is therefore provided with means 12 for accelerating waste flow F. These accelerating means 12 are arranged according to the invention directly at the outflow opening 7 of liquid trap 6. In the shown embodiment accelerating means 12 comprise a siphon installation arranged round and adjacently of standing part 10 of discharge pipe 9. The siphon installation and the standing conduit part 10 can herein be formed integrally with toilet 1 or be mounted on toilet 1 prior to delivery, so that the fitting operations remain limited to placing of toilet 1 and connection thereof to the lying part 11 of discharge pipe 9.

In order to prevent the operation of the siphon installation being affected by the solid parts S in waste flow F, means 13 are arranged on the inflow side of the siphon installation for separating at least a part of the liquid L from waste flow F. These separating means 13 here comprise an inflow edge 15 fitting smoothly onto a wall 14 of the standing conduit part 10 and inclining radially outward, and a deflecting edge 16 which is located opposite inflow edge 15 and which inclines radially inward as seen in the dropping direction (fig. 2). These two edges 15, 16 bound an annular feed opening 17 of the siphon installation.

The siphon installation itself comprises a tank 18 which is connected to feed opening 17 and provided with a siphon conduit 19 which debouches on the underside of tank 18. The volume of tank 18 is such that a number of flushes can be stored therein in order to enable a considerable

quantity of flushing liquid to be introduced into the discharge pipe at one time. Tank 18 is for instance dimensioned such that 6 litres of flushing liquid are delivered, since many pipe systems are dimensioned for this quantity.

Siphon conduit 19 is formed by a riser pipe 20 which is connected over a bend part 21 to a drop pipe 22. Arranged on the underside of drop pipe 22 is a pipe part 23 which is curved in a U-shape and which functions as a liquid seal, but which is dimensioned such that it is open in the rest position. This U-shaped pipe part 23 functioning as liquid seal debouches, as stated, on the underside of tank 18 into discharge pipe 9, this in the lying part 11 thereof. Because the feed side and the discharge side of the siphon installation communicate with each other via discharge pipe 9, no vent line is required therebetween as in conventional flow increasers.

The operation of discharge system 8 is now as follows. When toilet 1 is flushed, the waste flow F coming therefrom will reach discharge pipe 9 via outlet 5, liquid trap 6 and outflow opening 7. Here the waste flow F flows through the standing conduit part 10 to the lying conduit part 11. In standing part 10 the liquid L here flows mainly along the pipe wall 14, while the solid parts S drop through the middle of pipe 9. At the position of the siphon installation the liquid L then follows the inflow edge 15 which connects smoothly onto pipe wall 14, and thus flows into tank 18 where in the first instance it is collected (fig. 3) . The solid parts S drop together with a small part of the liquid L further through the middle of pipe 9. Because there is thus only little liquid available for further transport of the solid parts S, these will accumulate at the beginning of the lying conduit part 11. With each flushing

the liquid level increases further in tank 18 and in riser pipe 20 until it eventually reaches bend part 21.

When in this situation extra liquid flows into tank 18, riser pipe 20 will overflow via bend part 21 into drop pipe 22. As long as the amount of liquid flowing into tank 18 is small, the liquid flowing out of riser pipe 22 to drop pipe 22 will eventually flow via the U-shaped pipe part 23 to the outlet without this pipe part 23 herein being completely filled with liquid and thus functioning as liquid seal. However, as soon as a larger amount of liquid flows into the tank 18 already filled to its edge, as will be the case when toilet 1 is flushed, so much liquid flows out of riser pipe 20 into drop pipe 22 that the U-shaped pipe part 23 is completely filled with liquid, and thus functions as liquid seal. When the liquid L from this pipe part 23 flows to the discharge pipe, an underpressure is hereby created in drop pipe 22, whereby liquid is once again drawn out of riser pipe 20. This liquid once again fills pipe part 23, whereby it functions once again as liquid seal, and an underpressure is again generated in drop pipe 22 when pipe part 23 empties. This repeated opening and closing of the liquid seal takes place more and more quickly, whereby an uninterrupted flow of liquid will eventually be drawn out of riser pipe 20 into drop pipe 22 and through liquid seal 23 (fig. 4) . This continues until tank 18 is empty, whereby air will be drawn into riser pipe 22 and the underpressure in drop pipe 22 will be removed.

Since in this manner the whole content of tank 18 flushes through discharge pipe 9 at one time, a relatively high flow speed will be created therein, whereby the solid parts S which have settled in the lying conduit part 11 are flushed away.

The waste flow, by being accelerated immediately upon leaving the toilet or at least the liquid present therein being accelerated, can thus be transported in reliable manner through the discharge pipe to a sewer connection despite the relatively small volume of flushing water flowing through the toilet per flush. The flow increaser used herein can further be given a relatively small form, while the risk of blockage by fat residues is wholly obviated. Furthermore, due to the structural integration of the accelerating means with the toilet, the installation thereof can be considerably simplified.

Although the invention is elucidated above on the basis of an embodiment, it will be apparent to the skilled person that it is not limited thereto. Many variations in the configuration of the siphon installation and the separating means can be envisaged. The scope of the invention is therefore defined solely by the appended claims.