Quiet flushing system provided with a siphon

Abstract

The invention relates to a flushing system (10) comprising a tank (110), a water supply means and a siphon (120), the siphon comprising a descending pipe that opens into a toilet bowl and an ascending pipe that comprises at least one opening connecting the tank to the descending pipe, such that, after the flushing system has been actuated, the water contained in the ascending pipe flows back towards the tank, wherein: • - the tank comprises, at its base, a narrow portion forming a water collection cavity configured to collect at least some of the water flowing back from the ascending pipe to the tank after the flushing system has been actuated; and • - the water supply means comprises a pipe provided with an end (131) that opens into the collection cavity and is positioned so as to be submerged by the water flowing back into the tank after the flushing system has been actuated. According to the invention, the flushing system comprises a means (250) for unpriming the siphon (300), and the flow of air through the duct (252) of the unpriming means (250) is controlled by a solenoid valve (254).

Description

Title of the invention: SILENT TOILET FLUSHING SYSTEM EQUIPPED WITH A SIPHON TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a flushing system comprising a tank provided with a siphon for discharging water into a bowl.

[0002] The present invention relates more particularly to such a flushing system in which the cistern comprises at its base a narrow part forming a water collection cavity which is at least partly filled by the water flowing back from the rising pipe towards the cistern after a flushing operation, so as to immerse the end of a water supply pipe and to allow silent filling of the cistern between two flushing operations. STATE OF THE ART

[0003] The prior art discloses siphons positioned in a tank and initiated by the rise in the level of a liquid, usually water, in the tank up to a trigger threshold. The rise in the water level is usually caused by the action of a user, by pressing a button or turning a lever for example. The rise in the water is then initiated by adding water to the tank, by a water supply means, or initiated by immersing a volume in the water contained in the tank, as described in patent BE 395179. In all cases, the rise in the water level has the effect of causing the water contained in a rising water pipe forming one part of the siphon to overflow into a descending pipe forming the other part of the siphon.A siphon effect then begins, which is maintained until air is introduced into the downcomer, which has the effect of disabling the siphon, i.e. interrupting the flow of water from the tank to the downcomer.

[0004] Prior to each flush, the tank is filled to a predetermined height which is usually just below of the height corresponding to the siphon trigger threshold. Usually, the means of supplying water to the tank is placed at the top and on the side of the tank and consists of a water supply pipe equipped with a valve whose opening is controlled according to the level of water contained in the tank by means of a float. The float closes the valve at a predetermined height.

[0005] The end of the water supply pipe opening into the tank is usually placed high in the tank, which causes flow noises throughout the entire time the tank is being filled. OBJECTS OF THE INVENTION

[0006] The present invention aims to improve the flushing systems known from the prior art. One objective of the invention is to reduce noise when filling the cistern of the flushing system.

[0007] To this end, according to a first aspect, the invention relates to a flush toilet comprising a tank, a water supply means and a siphon configured to discharge water from the tank into a toilet bowl when the water height in the tank exceeds a priming height of the siphon, the siphon comprising a descending pipe opening onto the toilet bowl and an ascending pipe comprising at least one opening connecting the tank to the descending pipe, so that, after actuation of the flush toilet and discharge of a portion of the water from the tank into the bowl, the water contained in the ascending pipe flows back towards the tank, and in which: - the tank has at its base a narrow part forming a water collection cavity configured to collect at least part of the water flowing back from the rising pipe towards the tank after the flush has been activated, and - the water supply means comprises a pipe having one end opening into said collection cavity and positioned to be submerged by the water flowing back into the tank after the flush is activated.

[0008] A flush cycle is described below, involving the discharge of water from a toilet cistern into a toilet bowl. Prior to a flush cycle, the water level in the cistern, and therefore in the siphon riser pipe, will have been raised just below a priming threshold. During the flush cycle, the water level is still to exceed the priming threshold. Beyond this threshold, water overflows from the pipe. up to the down pipe of the siphon and primes the siphon. Water continuously flows through the up and down pipes to the bowl, until air from the tank or introduced by a depriming means primes the siphon.

[0009] Thanks to the provisions of the invention according to its first aspect, the end of the water supply pipe is submerged by the volume of water flowing back from the rising pipe of the siphon, once the siphon is unprimed. Thus, when water is brought through the water supply pipe to fill the cistern, this water is brought through the submerged end of the pipe, which has the effect of reducing the filling noise. Indeed, when the end of the water supply pipe opens into the upper part of the cistern, as is the case for most known flushes of the prior art, the filling noise is mainly due to the fall of the water which impacts the water already present in the cistern or its bottom when the cistern is empty.

[0010] It is emphasized that, in order to achieve this effect, the volume of water contained in the rising pipe flowing back towards the tank when the siphon is unprimed, must be sufficient to sufficiently fill the narrow part at the base of the tank, so as to immerse the end of the water supply pipe.

[0011] In other words, the volume delimited by the collection bowl is less than or equal to the volume delimited by the rising pipe.

[0012] It is further emphasized that, in order to achieve the effect intended by the invention, it is understood that the flush is configured so that the water flowing back from the tank flows towards the narrow part of the tank.

[0013] 11 It is understood that the volume of the riser pipe corresponds to the volume of water contained in the riser pipe flowing back towards the tank when the siphon is unprimed. Thus, the dimensions of the riser pipe, the dimensions of the narrow part of the tank and the positioning of the end of the water supply pipe must be chosen so as to immerse the end of the water supply pipe by the volume of water flowing back from the riser pipe.

[0014] According to the first aspect of the invention, the tank has at its base a narrow part forming a water collection cavity. By "narrow part" is meant a part of the tank whose dimensions are smaller than the average dimension of the tank. Thus, the tank observed in cross-section will have, at the level of the narrow part of the tank, sections whose perimeter is smaller than the average perimeter of the sections over the entire height of the tank, for example. On the tank observed in longitudinal section, the narrow part may be characterized by the reduction in the width of the tank, in the bottom of the tank. So that the tank observed in longitudinal section may have a funnel shape or include a deformation constituting the water collection cavity.

[0015] It is emphasized that the narrow part of the tank may be delimited by the walls of the tank, as is the case in examples illustrated in the present application, or may be formed by added parts arranged in the tank. Thus, one or more parts weighted or fixed to the tank may be arranged in the bottom of the tank, so that the walls of said parts delimit a collection cavity within the meaning of the present application.

[0016] Due to the presence of the narrow portion, the water height in the water collection cavity formed by this portion of the cistern rises sufficiently to submerge the end of the water supply pipe. Cisterns known from the prior art usually have a flat bottom, so that the water rises little in the cistern when water flows back from the riser pipe after a flush actuation. In contrast, the water rises high in the narrow portion of the cistern, even with the small volume of water flowing back from the riser pipe.

[0017] Another advantage of the presence of the narrow part forming the collection cavity is that the dimensions and shape of the siphon can be selected to ensure good siphon performance, i.e. easy priming, good water flow and prevention of untimely loss of priming without being constrained by the choice of the volume of the downcomer. Indeed, by adjusting the dimensions of the narrow part of the siphon and the positioning of the end of the water supply pipe, it will be possible to obtain the effect of immersing the end of the water supply pipe by the volume of water flowing back from the upcomer.

[0018] In embodiments, the at least one opening connecting the reservoir to the riser pipe is positioned in the water collection cavity.

[0019] These arrangements increase the amount of water discharged from the cistern to the bowl. The reduced size of the narrow part of the cistern has the effect of keeping the opening connecting the cistern to the downpipe submerged for a longer time when the water level in the cistern empties following a flush. Thus, the entry of air through said opening is delayed.

[0020] In embodiments, the narrow portion of the reservoir has the shape of a cone truncation. Preferably, the narrow portion has the shape of a right cone truncation.

[0021] It is emphasized that any other shape making it possible to delimit a narrow part within the meaning of the invention may be implemented. As a non-limiting example, a narrow part of tubular shape, parallelepiped shape or in the form of a truncation of a sphere may be cited.

[0022] In embodiments, the reservoir has a portion whose cross-section is reduced in size and which is positioned at the priming height of the siphon.

[0023] In other words, the tank is formed of several tank parts superimposed on each other and a tank part positioned at the level of the siphon priming height has a reduced section size.

[0024] By reduced section size we mean that the perimeter of the section is smaller than the average perimeter of the sections of the tank.

[0025] Thanks to these provisions, the volume of water that needs to be poured into the cistern to increase the water height in the cistern is lower in the part of the cistern positioned at the siphon priming height. Thus, flushing is made easier or faster, because the volume of water that needs to be moved to prime is smaller and the faster rise in the water level makes priming the siphon easier. It is emphasized that the same effect is achieved whether the siphon is actuated by adding water to the cistern or by immersing a volume in the cistern to raise the water level.

[0026] In embodiments, the reservoir further has a reservoir portion positioned above the portion having a reduced cross-sectional size and having a cross-sectional size larger than the cross-sectional size of the portion having a reduced cross-sectional size.

[0027] Thanks to these arrangements, a larger volume is present in the tank above the reduced section portion which is at the siphon priming height. This volume can be used to house elements of the flush, for example part of the water supply means or all or part of a depriming means.

[0028] According to a second aspect of the invention which can be combined with the first, the invention relates to a flush toilet comprising a tank, a water supply means and a siphon configured to discharge water from the tank into a toilet bowl when the water height in the tank exceeds a priming height of the siphon, the siphon comprising a downpipe opening onto the toilet bowl and an upflow pipe comprising at least one opening connecting the tank to the downflow pipe, the flush further comprising a means for depriming the siphon, configured to allow the introduction of air into the downflow pipe of the siphon after priming the siphon and thus prematurely deprime the siphon. These arrangements make it possible to reduce the volume of water discharged when a toilet is flushed and thus save water.

[0029] In embodiments, the siphon depriming means comprises a pipe having one end connected to the downpipe and one end connected to an air source, preferably arranged in the gaseous head of the tank, and in which the passage of air through the pipe of the depriming means is regulated by a solenoid valve.

[0030] Preferably, the opening of the solenoid valve is controlled by wireless remote control means.

[0031] Thanks to these provisions, it is not necessary to provide electrical wires between the solenoid valve of the depriming means and the means of controlling the solenoid valve, for example a human-machine interface or an electronic card. The space requirement is therefore reduced, as is the risk of electrical wires coming into contact with the water contained in the tank.

[0032] In embodiments, the siphon depriming means comprises a flexible pipe having one end connected to the downcomer and a movable end configured to be positioned at different heights in the tank.

[0033] The flexible pipe allows air to flow from the cistern to the downcomer, but only when the moving end is exposed to air. Conversely, when the moving end is completely submerged by water contained in the cistern, air does not circulate through it. Thus, when the toilet is flushed, the siphon is primed and water flows from the cistern to the bowl, until the water level in the cistern has dropped to the height where the moving end of the flexible pipe is positioned.

[0034] In embodiments, the defusing means comprises a plurality of supports placed at different heights and a rod secured to the flexible conduit and provided with a means for suspending the rod from the plurality of supports placed at different heights.

[0035] For example, the plurality of supports arranged at different heights is a grid or a ladder-shaped metal piece, each of the rungs of which is a support on which the rod can be suspended.

[0036] For example, the rod suspension means is a curved end of the rod configured to be suspended from the brackets placed at different heights.

[0037] In embodiments, the flush includes a variable-sized balloon that can be filled with a fluid, such as water or air, on command to vary its volume. The balloon is disposed in the cistern at least partially below the priming height of the siphon. The variation in the volume of the balloon causes a variation in the volume of water below the priming height of the balloon, thereby changing the volume of water discharged to the bowl when the flush is actuated.

[0038] According to a third aspect, the invention relates to a method for operating a flush toilet comprising a tank, a water supply means and a siphon configured to discharge water from the tank into a toilet bowl when the water height in the tank exceeds a priming height of the siphon, the siphon comprising a descending pipe opening onto the toilet bowl and an ascending pipe comprising at least one opening connecting the tank to the descending pipe, in which: - during a flushing step, the siphon is primed and part of the water from the tank flows into the bowl, - during a siphon depriming step, the water contained in the rising pipe flows back towards the tank, towards a water collection cavity and, - during a tank filling step, water is brought into the tank through a pipe opening into said collection cavity and immersed by the water during the siphon depriming step.

[0039] The aims, advantages and particular characteristics of the method which is the subject of the present invention being similar to those of the flushing toilet according to the first aspect which is the subject of the present invention, they are not recalled here.

[0040] In embodiments, after the flushing step and before unpriming the siphon, water is brought into the tank through the pipe opening into the collection cavity, so as to increase the volume of water discharged into the bowl.

[0041] These provisions have the effect of preventing the siphon from being unprimed or delaying the siphon from being unprimed because the water brought into the cistern feeds the siphon. Thanks to these provisions, the volume of water discharged into the bowl following a flush can be deliberately increased.

[0042] In embodiments, the step of filling the tank comprises a step of measuring a value representative of the height of water in the tank and pouring the water into the tank until a predetermined height of water, lower than the priming height of the siphon, is reached.

[0043] Thanks to these arrangements, precise filling, controlled by a sensor measuring a value for the water height in the cistern, is achieved. It is emphasized that these arrangements are particularly advantageous for a flush system comprising a siphon as for the flush system of the invention. Indeed, it is important that the water level in the cistern is raised just below the priming height of the siphon between two flushes, in order to allow rapid actuation of the flush. On the other hand, precise control of the water height in the cistern is useful to avoid overfilling the cistern, which would result in untimely priming of the siphon and wasting water. BRIEF DESCRIPTION OF THE FIGURES

[0044] Other advantages, aims and particular characteristics of the invention will emerge from the following non-limiting description of at least one particular embodiment of the flushing toilet which is the subject of the present invention, with reference to the appended drawings, in which:

[0045] [Fig 1] represents, schematically and in longitudinal section view, a flush toilet according to a first particular embodiment of the invention,

[0046] [Fig 2] represents, schematically and in longitudinal section view, a flush toilet according to a second particular embodiment of the invention, and

[0047] [Fig 3] represents, schematically and in longitudinal section view, a flush toilet according to a third particular embodiment of the invention.

[0048] The reference numbers mentioned in the figures relate to: 10, 20, 40 Toilet flush 110 Tank 112 Narrow part at the base of the tank 114 Collection cavity 115 Siphon housing 116, 118 Portions of the reservoir 130 Water supply line 131 End of the supply line 135, 136 Valves 170 Water height sensor 175 Electronic card 180 Toilet flush button 250 Defusing Means 252 Driving 254 Solenoid valve 290 Balloon 291 Stop 300 Siphon 305 Opening between the riser pipe and the tank 310 Upward driving 320 Downhill Driving 350 Connector 380 Joint 438 Float 450 Defusing Means 452 Smooth driving 454 Flexible conduit end 460 Rod 461, 462 Supports 480 Lever 481 Diver volume 800 Support housing the 110 tank 905 Water height corresponding to the priming threshold DETAILED DESCRIPTION OF THE INVENTION

[0049] This description is given without limitation, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment in an advantageous manner.

[0050] This description is given without limitation, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment in an advantageous manner.

[0051] Figure 1 shows a toilet flushing system 10 for sanitary facilities according to a first particular embodiment of the invention, which comprises a siphon 300. The toilet flushing system 10 comprises a tank 110, mounted in a support 800 positioned above a toilet bowl (not shown). The support 800 housing the tank 110 is for example mounted on a wall above a toilet bowl, mounted in a box or even directly attached to the bowl.

[0052] The reservoir 110 is illustrated in longitudinal section. It is emphasized that the cross-section of the reservoir 110 may be circular or rectangular or adopt any other shape, provided that the reservoir 110 has a sufficient volume to dispense the desired volume of water. Advantageously, the cross-section (not shown) of the reservoir is rectangular to reduce the size of the reservoir 110.

[0053] The flushing system 10 comprises a water supply means configured to fill the tank 110. Said water supply means comprises a pipe 130 connected to a water source, for example to a municipal water circuit, a valve 136 being able to be opened or closed on command of the user of the flushing system or on automatic command. One end 131 of the pipe 130 is positioned in the tank 110, so that the opening of the valve 136 has the effect of discharging water into the tank 110 through the open end 131 of the pipe 130.

[0054] Advantageously, the valve 136 is a solenoid valve controlled by an electronic card 175. The opening of the valve 136 in order to discharge water into the tank can be controlled as a function of a water level contained in the tank 110 or as a function of an interaction of the user with a human-machine interface, for example a button 180. In order to ensure the proper functioning of a flushing cycle, as described previously in the present application, the valve 136 is opened prior to triggering the flush and kept open until the tank 110 is partially filled with water to a height substantially lower than the height corresponding to the threshold 905 for priming the siphon 300.

[0055] Advantageously, the water level in the tank 110 is detected by a means for measuring a value representative of the height of water in the tank 100. For example, this means is an optical sensor 170 measuring the distance between the sensor 170 and the surface of the water. In other embodiments, one or more optical, capacitive or resistive type sensors are implemented.

[0056] In embodiments (not shown), at least one sensor detecting the water height in the tank 110 by immersing the sensor is implemented. For example, a sensor is positioned just below the height corresponding to the priming threshold in the tank 110, so that, when this sensor detects that it is submerged, the valve 136 is cut off. A plurality of sensors detecting the water height in the tank 110 by immersion may be positioned at different heights in the tank to detect the water height in the tank.

[0057] During the flush cycle, following an automatic command or following a press of the button 180 by a user, the water level in the tank 110 can be raised above the priming threshold 905 by opening the valve 136. The water thus added to the tank 110 causes water to overflow from an upflow pipe 310 of the siphon 300 to a downflow pipe 320 of the siphon and primes the siphon. The water continuously flows through the siphon pipes to a bowl, until the water runs out in the tank 110 and air from the tank enters the siphon 300 and deprimes it.

[0058] Advantageously, a second valve 135 is provided on the pipe 130 to stop the flow of water to the tank 110, for example in the event of a leak or during a maintenance operation on the flushing system 10. The valve 136 is for example a tap or a manual valve of the all-or-nothing type. During normal operation of the flushing system 10, the valve 135 is always open.

[0059] It is noted that the valves 135 and 136 are preferentially positioned on sections of the pipe 130 which are housed inside the tank 110, so that water flows at the level of these valves, in the event of a leak or when handling a valve, flow into the tank 110.

[0060] The siphon 300 is for example a cylindrical, preferably tubular, siphon formed by an outer cylinder, an inner cylinder housed in the outer cylinder and a connector 350, configured to establish a sealed connection between the two cylinders. According to the example illustrated in FIG. 1, the siphon 300 is centrally positioned, vertically, in the tank 110. The siphon 300 is mounted in a housing 115 provided in the bottom of the tank 110. The siphon 300 comprises an annular seal 380 which can be inserted into said housing so that the siphon 300 is held vertically in place in the housing 115 and so that the descending pipe of the siphon 300 is made to communicate with a water evacuation pipe towards a bowl. One or more openings 305 are pierced around the perimeter of the siphon 300 at its base in order to allow the circulation of water from the reservoir 110 to the rising pipe 310 of the siphon 300.

[0061] The tank 110 comprises a narrow portion 112 formed by a narrowing of the walls of the tank 110 at its base. The narrow portion 112 forms a water collection cavity 114 configured to collect at least a portion of the water flowing back from the riser 310 to the tank 110 after a flush operation.

[0062] It is emphasized that the pipe 130 of the water supply means has an end 131 opening into the collection cavity 114. The end 131 of the pipe 130 is positioned to be immersed by the water flowing back into the tank 110 after the flush 10 is actuation. Advantageously, one or more openings 305 pierced around the periphery of the siphon 300 are also positioned in the water collection cavity 114.

[0063] In the example shown in Figure 1, the narrow portion 112 of the reservoir 110 has the shape of a truncation of a right cone. In other embodiments, the shape of the narrow portion is hemispherical or rectangular. It is emphasized that the narrow portion can be formed by the walls of the reservoir 110 or be formed by any other structure, for example by inserts of suitable shape placed in the reservoir 110, provided that the structures implemented make it possible to form a collection cavity.

[0064] The tank 110 has a portion 116 whose section is of reduced size. This portion of the tank is positioned at the priming height 905 of the siphon 300. This narrowing of the tank at this level makes it possible to raise the water level more quickly when the flush 10 is activated.

[0065] The tank 110 further comprises a portion 118 of the tank 110 placed above the portion 116, the cross-section of which is of reduced size. The cross-section of the portion 118 is larger than the cross-section of the portion 116. Thus, the tank 110 has a larger interior volume on its upper part. This shape is advantageous because it makes it possible to house in the tank 110 elements, 130, 135, 136 of the water supply means, in particular the valves 135 and 136, which discharge water into the tank 110 in the event of a leak or during maintenance of the flush 10.

[0066] Figure 2 shows a toilet flushing system 20 for sanitary facilities according to a second particular embodiment of the invention. The elements of the toilet flushing system 20 bearing the same reference number as the elements of the toilet flushing system 10 are similar and are not described again here.

[0067] The flush 20 is distinguished from the flush 10 in that it comprises a means 250 for depriming the siphon, configured to introduce air into the descending pipe 320 of the siphon after priming the siphon 300 and thus prematurely depriming the siphon.

[0068] The depriming means 250 comprises a tubular pipe 252 placed vertically in the tank 110. The pipe 252 of the depriming means 250 comprises a first end secured to the connector 350 and connected to the descending pipe 320. The other end of the pipe 252 opens into the gaseous airspace of the tank 110. A solenoid valve 254 is fixed to the pipe 252, preferably at the end opening into the gaseous airspace. The passage of air through the pipe of the depriming means is regulated by a solenoid valve.

[0069] The opening of the solenoid valve 254 is controlled by wireless remote control means, for example integrated into the electronic card 175. In embodiments, an interface is provided allowing the user of the flush 20 to choose a water-saving flush actuation, in which the depriming means interrupts the discharge of water into the bowl prematurely, after a determined duration, counted from the actuation. This time can be pre-recorded or configured by the user of the flush 20.

[0070] In embodiments, the flush 20 comprises a balloon 190 disposed in the tank 110 at least partly below the priming height 905 of the siphon 300. The balloon is filled on command with a fluid, preferably with air or with water, conveyed to the balloon by means of a pipe and a pump or a valve [not shown]. The balloon is preferably formed of a flexible and deformable polymer. Particularly when the balloon 190 is configured to be inflated by air, a stop 191 may be provided to prevent the balloon 190 from floating to the top of the tank 110. It is emphasized that the implementation of a portion 116 of the tank 110 of narrow section is particularly suitable in this case, because it has the double advantage of facilitating the priming of the siphon 300 and of forming the stop 191.

[0071] Figure 3 shows a toilet flushing system 40 for sanitary facilities according to a third particular embodiment of the invention. The elements of the toilet flushing system 40 bearing the same reference number as the elements of the toilet flushing system 10 or 20 are similar to the latter and are not described again here. It is noted that the toilet flush 40 differs from the toilet flushes 10 and 20 in that it does not include a support housing the tank 110. The tank 110 is therefore visible from the outside and self-supporting.

[0072] The flush 40 is distinguished in that the opening of the valve 136 is controlled as a function of the position of a float 438, so as to keep the valve 136 open unless the level of the water contained in the tank 110 exceeds a predetermined height. The actuation of the siphon 300 of the flush 40 is carried out by means of a lever 480 articulated with a plunger volume 481 configured to be lowered on command of the lever 480 in order to raise the water level in the tank 110 and thus prime the siphon 300.

[0073] The flush 40 comprises a means 450 for depriming the siphon, configured to introduce air into the descending pipe 320 of the siphon after priming the siphon 300 and thus prematurely deprime the siphon.

[0074] The siphon depriming means 450 comprises a flexible pipe 452 comprising a first end secured to the connector 350 and connected to the descending pipe 320 and a second end 454 which can be moved by the user and configured to be positioned at different heights in the tank 110.

[0075] To do this, the depriming means 450 comprises a plurality of supports, 461, 462, placed at different heights in the tank 110. Said supports, 461, 462, are configured to cooperate with a rod 460 secured to the second end 454 of the flexible pipe 452. The rod is for example a rigid rod, preferably metallic or made of plastic. A suspension means is provided for hanging the rod 460 from a support, 461, 462. The suspension means is for example a curved end of the rod 460 configured to be housed in a support 461, 462. The plurality of supports can be formed by a ladder-shaped part, each of the rungs of which is a support on which the rod 460 can be suspended.

[0076] The position of the end 454 determines the volume of water that will be discharged into the bowl when the flush 40 is actuated. In fact, the water will gradually descend into the tank after the siphon 300 has been primed, until the end 454 of the flexible pipe 452 is exposed to the air, which will have the effect of introducing air into the descending pipe 320 and depriming the siphon.

Claims

CLAIMS

1. A flushing device [10, 20, 40] comprising a tank [110], a water supply means and a siphon [300] configured to discharge water from the tank (110) to a toilet bowl when the water height in the tank [110] exceeds a priming height (905) of the siphon (300), the siphon comprising a downcomer opening onto the toilet bowl and an upcomer (310) comprising at least one opening (305) connecting the tank to the upcomer (310), such that, after actuation of the flushing device and discharge of a portion of the water from the tank to the bowl, the water contained in the upcomer (310) flows back towards the tank, characterized in that: - the tank (110) comprises at its base a narrow part (112) forming a water collection cavity (114) configured to collect at least part of the water flowing back from the rising pipe (310) towards the tank (110) after actuation of the flush, and - the water supply means comprises a pipe (130) provided with an end (131) opening into said collection cavity and positioned to be immersed by the water flowing back into the tank after actuation of the flush and which comprises a depriming means (250) of the siphon (300), configured to introduce air into the descending pipe (320) of the siphon (300), in which the depriming means of the siphon comprises a pipe (252) provided with an end connected to the descending pipe (320) and an end connected to an air source, preferably arranged in the gaseous headspace of the tank (110), and in which the passage of air through the pipe (252) of the depriming means (250) is regulated by a solenoid valve (254).

2. A flush valve (10, 20, 40) according to the preceding claim, wherein the at least one opening (305) connecting the reservoir (110) to the riser pipe (310) is positioned in the water collection cavity.

3. A flush toilet (10, 20, 40) according to any preceding claim, wherein the narrow portion (112) of the reservoir (100) has the shape of a cone truncation.

4. A flush [10, 20, 40] according to any preceding claim, wherein the reservoir [110] has a portion [116] of reduced cross-section which is positioned at the priming height (905) of the siphon (300).

5. A flush toilet (10, 20, 40) according to the preceding claim, wherein the reservoir (110) further comprises a reservoir portion (118) placed above the portion (116) whose cross-section is reduced in size and whose cross-section is larger than the cross-section of the portion (116) whose cross-section is reduced in size.

6. A method of operating a flush toilet according to one of claims 1 to 5, comprising a reservoir, a water supply means and a siphon configured to discharge water from the reservoir to a toilet bowl when the water height in the reservoir exceeds a priming height of the siphon, the siphon comprising a descending pipe opening onto the toilet bowl and an ascending pipe comprising at least one opening connecting the reservoir to the ascending pipe, characterized in that: - during a flushing step, the siphon is primed and part of the water from the tank flows into the bowl, - during a siphon depriming step, the water contained in the rising pipe flows back towards the tank, towards a water collection cavity and, - during a tank filling step, water is brought into the tank through a pipe opening into said collection cavity and immersed by the water during the siphon depriming step.

7. A method of operating a flush toilet according to the preceding claim, wherein, after the step of actuating the flush toilet, water is brought into the tank through the pipe opening into the collection cavity, so as to increase the volume of water discharged into the bowl.

8. A method of operating a flush toilet according to claim 6 or 7, wherein the step of filling the tank comprises a step of measuring a value representative of the height of water in the tank and a discharge of water into the tank until a predetermined water height, lower than the siphon priming height, is reached.

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