WO2008039063A1

WO2008039063A1 - Device and system for draining water from a storage tank

Info

Publication number: WO2008039063A1
Application number: PCT/NL2007/000242
Authority: WO
Inventors: Johannus Donaes Jacobus Platteel; Sjoerd Peter Wouda
Original assignee: Ecoplay International BV
Current assignee: Ecoplay International BV
Priority date: 2006-09-25
Filing date: 2007-09-25
Publication date: 2008-04-03
Anticipated expiration: 2009-03-25
Also published as: NL1032567C2

Abstract

The present invention relates to a device for draining water from a storage tank, comprising: a closing member which is arranged movably between a first position closing a discharge opening in a bottom of the storage tank and a second position leaving the discharge opening substantially clear; and opening means for keeping the second position open during draining of the storage tank. The invention also relates to a system for the reuse of greywater comprising such a device.

Description

DEVICE AND SYSTEM FOR DRAINING WATER FROM A STORAGE TANK

The present invention relates to a device for draining water from a storage tank, and to a system provided with such a device .

Known from the prior art are devices for draining water from a storage tank, such as for instance a cistern of a toilet. Although mains water is usually used to flush a toilet, it is also possible to use lightly contaminated water for this purpose. In order to make efficient use of energy and environment, less clean non-potable water is used for some applications, such as for instance flushing a toilet, instead of mains water which has been treated with great effort and at great cost in wastewater purification plants. It is thus possible to envisage the use of collected rainwater and the reuse of lightly contaminated bath and shower water, also referred to as greywater. In addition to saving water for the user, the use of greywater furthermore results in a proportional reduction in the impact on the sewage system.

In conventional systems used to discharge water present in a storage tank such as a cistern, a quantity of water remains behind in the storage tank after each flush. Although this does not cause problems when mains water is used, this will however generally be the case when greywater is applied. Because greywater is lightly contaminated water, this can eventually result in undesirable odour nuisance, and the water already present in the storage tank for a longer period of time can infect the water freshly supplied to the storage tank. In order to prevent odour nuisance and for instance legionella, and be able to discharge as much as possible of the contamination accumulated in the storage tank during flushing, there is a need for a device for draining water from a storage tank which is able to empty the storage tank almost completely or completely.

The present invention therefore has for its object to provide a device for draining water from a storage tank which avoids the above stated problems and wherein, particularly after a flushing, less water remains behind in the storage tank than is the case with conventional draining systems.

Said object is achieved with the device for draining water from a storage tank according to the invention, comprising:

- a closing member which is arranged movably between a first position closing a discharge opening in a bottom of the storage tank and a second position leaving the discharge opening substantially clear; and - opening means for keeping the second position open during draining of the storage tank.

When water present in the storage tank flows out through the discharge opening in the bottom of the storage tank, this outflowing water exerts an upward force on the closing member. This upward force - to which reference is made in this patent text as the pushing force of the outflowing water, or in short pushing force - is caused according to the Newton's third law (the law of action and reaction) . In addition, the closing member will be partially submerged in the water, whereby an amount of water is displaced and, according to Archimedes' law, an upward force is exerted on the closing member. According to Archimedes' law a body which is wholly or partially submerged in a liquid is subjected to an upward force which is equal to the weight of the displaced liquid. The more water flows out of the storage tank, the more the pushing force will decrease and the quantity of water displaced by the closing member will decrease, whereby the upward force according to Archimedes' law will also decrease.

Because the device according to the present invention comprises opening means which hold back the closing member when the resultant upward force - which is the sum of the pushing force of the water and the upward force according to Archimedes' law - exerted on the closing member is smaller than the force of gravity acting on the closing member, the closing member according to the device of the present invention will remain longer than is the case in conventional systems in a position in which the discharge opening to the discharge conduit is not closed. The opening means according to the invention are additional compared to a conventional system. In conventional systems the closing member will be displaced to a closing position when the resultant upward force is smaller than the force of gravity acting on the closing member. Since the device according to the present invention holds the closing member for a longer time in a non-closing position, more water will be drained via the discharge opening and the discharge conduit, whereby less water remains behind in the storage tank than is the case with conventional flushing systems .

In a preferred embodiment of the present invention the opening means pass through an unstable intermediate position between the first position of the closing member closing the discharge opening and the second position of the closing member leaving the discharge opening clear. Because it requires some effort to pass through this unstable intermediate position, which is a ^λdead point', the opening means are suitable for at least retaining for a longer time the second position of the closing member leaving the discharge opening clear. More water can hereby be drained via the discharge opening. In a preferred embodiment of the present invention the opening means comprise a moment-transmitting member which is arranged pivotally on the storage tank and which is connected pivotally to the closing member, and tensioning means arranged between the moment-transmitting member and the storage tank.

By embodying the opening means as a pivotable moment-transmitting member with tensioning means a system is provided which is able to hold the closing member temporarily in an open position in mechanical manner to enable complete or almost complete emptying of the storage tank. Because use is made of a mechanical principle, this preferred embodiment has the advantage of being a reliable, robust and energetically favourable embodiment requiring little maintenance. Because the system operates in purely mechanical manner, the system does not consume any electrical energy due to the absence of electricity and the danger of short-circuiting moreover need not be taken into account. In a further preferred embodiment of the present invention the moment-transmitting member comprises a first pivot point at which the moment-transmitting member is pivotally connected to the closing member, a second pivot point at which the moment-transmitting member is pivotally connected to the storage tank, and a fixing point at which the moment-transmitting member is connected to the tensioning means, and wherein the two pivot points, together with the fixing point, define a plane. The fixing point is situated some distance from a line through the first and second pivot points . Due to a suitable relative positioning of the first and second pivot points and the fixing point of the moment-transmitting member, a moment-transmitting member is provided which is adapted such that, depending on the position in which the closing member is situated, a determined moment is exerted on the closing member by the moment-transmitting member. When the closing member is situated in a position leaving clear the discharge opening in the bottom of the storage tank, the moment-transmitting member is adapted such that a moment is then exerted on the closing member which is able, together with the resultant upward force resulting from the pushing force and Archimedes' law, to overcome the force of gravity and hold the closing member open in a position leaving clear the discharge opening in the bottom of the storage tank.

It is noted that when the closing member is situated in its position closing the discharge opening to the discharge conduit, a downward directed moment of force is exerted on the closing member by the moment-transmitting member. This enhances sealing of the discharge opening in the bottom of the storage tank and can be deemed an additional advantage of a suitable relative positioning of the two pivot points and the fixing point of the moment-transmitting member.

In a further preferred embodiment of the present invention the distance between the second pivot point and the fixing point of the moment-transmitting member is smaller than the distance between the fixing point of the moment-transmitting member and the fixing point of the storage tank between which the tensioning means are arranged.

Making the distance between the second pivot point and the fixing point of the moment-transmitting member smaller than the distance between the fixing points between which the tensioning means are arranged guarantees that the moment exerted by the moment-transmitting member on the closing member has a transition point, at which the moment changes sign. At this transition point of the intermediate position the moment-transmitting member passes through an unstable position. The device is hereby able on the one hand to hold the closing member open for a longer time in a position leaving clear the bottom of the storage tank, while on the other hand it exerts a downward directed moment on the closing member when this latter is situated in a position closing the bottom of the storage tank, which enhances sealing.

In a further preferred embodiment of the present invention the first and second pivot points and the fixing point have a relative position such that during use a moment exerted on the closing member by the moment-transmitting member changes sign, wherein the moment-transmitting member passes through the unstable intermediate position, as the closing member progresses through the movement from the second position substantially holding open the discharge opening to the first position substantially closing the discharge opening.

In a further preferred embodiment of the present invention the closing member is a substantially elongate hollow body. By giving the closing member an elongate and hollow form it can function as an overflow channel for disposing of excess water fed to the storage tank. An excess of water flows into the closing member at the top and is discharged through the hollow of the closing member to the discharge conduit .

In a further preferred embodiment of the present invention the tensioning means comprise a spring or an elastic . By embodying the tensioning means as a spring or an elastic the device according to the present invention can apply a moment to the closing member in energetically favourable manner via the moment-transmitting member. In a further preferred embodiment of the present invention the device comprises adjusting means which are adapted to fix the tensioning means in different positions on the storage tank. Through the arrangement of adjusting means it is possible to fix the tensioning means in different positions, this making it possible to influence the tensioning force exerted by the tensioning means on the moment-transmitting member and in this way to adjust as desired the moment exerted by the moment-transmitting member on the closing member. A flexibly adjustable system is obtained in this way.

In a further preferred embodiment of the present invention the device further comprises a drive member which is arranged between the storage tank and the moment-transmitting member and which is adapted to move the closing member counter to a moment exerted on the closing member by the moment-transmitting member, and a control unit for controlling the drive member.

It is also possible to exert a moment on the closing member via the moment-transmitting member such that the closing member is held upward in its open position even when all the water has flown out of the storage tank. By arranging a drive member between the storage tank and the moment-transmitting member, this drive member can counteract the moment exerted by the tensioning means on the moment-transmitting member and push the moment-transmitting member over its "dead point' or "transition point' characterizing the unstable intermediate position. The moment herein changes sign so that the closing member can move to a position closing the storage tank. A control unit is arranged for controlling the drive member, for instance at a preset time interval after emptying of the storage tank has been activated. It is noted that the drive member can also drive the closing member directly instead of indirectly via the moment-transmitting member.

In a further preferred embodiment of the present invention the device further comprises a sensor for sensing the water level in the storage tank, and the control unit is adapted to control the drive member subject to the water level present in the storage tank sensed by the sensor.

A more flexibly adjustable system is obtained by adding a sensor. In a further preferred embodiment of the present invention the device comprises a sensor for sensing the water level in the storage tank, and a control unit for controlling the opening means subject to the water level present in the storage tank sensed by the sensor. A system is obtained in this manner which is able to control the opening means without tensioning means. It is for instance possible to envisage an electric motor activating means which engage with the closing member for the purpose of holding this member temporarily upward under the control of the control unit.

In a further preferred embodiment of the present invention the opening means comprise at least an electromagnet which is connected to the control unit and which is adapted to hold the closing member in an open position subject to a signal received by the control unit.

By embodying the opening means as an electromagnet the closing member can, when it is also provided with a magnetic part, be held in a raised position by energizing the electromagnet with the control unit. This provides a practical alternative embodiment.

The present invention further relates to a system for the reuse of greywater, wherein a device according to any of the embodiments described in this patent specification is applied.

Although complete emptying of a storage tank offers multiple advantages, such as for instance the option of applying a smaller storage tank while having the same flushing volume, the most important advantage of the present invention is that lightly contaminated water can be wholly drained, and a system is thereby provided which is less susceptible to odour nuisance and infection. The present invention therefore relates particularly to systems which reuse greywater.

In the following description preferred embodiments of the present invention are further elucidated with reference to the drawing, in which:

Figure 1 shows a cross-sectional front view of a preferred embodiment for draining water from a storage tank according to the present invention in a first situation, wherein the storage tank is filled with water;

Figure 2 shows the device of figure 1 in a second situation; Figure 3 shows the device of figure 1 in a third situation;

Figure 4 shows the device of figure 1 in a fourth situation;

Figure 5 is a front view of a second embodiment of the present invention; and

Figure 6 is a front view of a third embodiment of the present invention.

The preferred embodiment of the present invention as shown in figures 1-4 comprises a cistern 2, wherein cistern 2 has an upper wall 4 which can also function as cover, side walls 6, a bottom 12 and (not shown) rear wall 8 and front wall 10. Arranged in a side wall 6 in figure 1 are means for supplying water 14 which comprise an external feed conduit 16, closing means 18 and an internal feed conduit 20. Such water supply means 14 can also be arranged in one of the other walls, such as for instance rear wall 8.

Closing means 18 of water supply means 14 are operated by means of a switching mechanism 22 comprising a float 24 and arms 26 and 28 which rotate about a pivot point 30. Arranged in bottom 12 of cistern 2 is a discharge opening 32 to which is connected a discharge conduit 34. In the situation shown in figure 1 discharge conduit 34 is closed by a flush pipe 36 which comprises a seal 38 on its side located close to bottom 12.

By means of moving operating handle 60 in upward direction manually or using a drive member the device is activated and a toilet connected to discharge conduit 34 is provided with water from cistern 2. Operating handle 60 is herein moved away from upper wall 4 of cistern 2 whereby, via an operating rod 58 situated between operating handle 60 and flush pipe 36, flush pipe 36 is moved upward from the bottom 12 of cistern 2 such that discharge opening 32 in bottom 12 is left clear and water is drained from cistern 2 to the toilet via discharge conduit 34.

In the situation shown in figure 1 cistern 2 is filled with so much water that switching mechanism 22 holds closing means 18 of water supply means 14 in a closing position. When the water level in cistern 2 rises, float 24 is displaced in upward direction whereby arms 26 and 28, which pivot about pivot point 30, move closing means 18 into a closing position.

Flush pipe 36 is situated in a first position in which it closes the discharge opening 32 to discharge conduit

34. The device further comprises a knee-piece 44 mounted on cistern 2 at a pivot point 46. Knee-piece 44 is connected pivotally to flush pipe 36 at a first pivot point 42. Knee-piece 44 is a further connected at its fixing point 50 to a spring 52 arranged between fixing point 50 of knee-piece 44 and a fixing point 54 of cistern 2. It will be apparent to a skilled person that other tensioning means, such as for instance an elastic, can also be applied instead of a spring.

In a preferred embodiment of the present invention the fixing point 54 at which spring 52 is mounted on cistern 2 takes an adjustable form. In figure 1 fixing point 54 is displaceable using adjusting means 56, which in this embodiment comprise a plurality of recesses. The unstable intermediate position, where the moment exerted by spring 52 on knee-piece 44 changes sign, will shift due to displacement of fixing point 54. The system can be adjusted in this manner. Figure 2 shows the situation in which operating handle 60 is moved upward, whereby flush pipe 36 is also moved in upward direction away from bottom 12 of cistern 2 by means of operating rod 58. Because discharge opening 32 is no longer sealed by sealing member 38 in the upwardly moved position of flush pipe 36 as shown in figure 2, the water present in cistern 2 will be drained to the toilet via discharge opening 32 and discharge conduit 34. When flush pipe 36 is moved in upward direction, the knee-piece 44 which is connected to flush pipe 36 at its pivot point 42 will rotate about its pivot point 46, wherein fixing point 50 connected to spring 52 will also undergo a displacement. As flush pipe 36 is displaced further in upward direction from the situation shown in figure 2 to the situation shown in figure 3, pivot point 42 is moved further upward, whereby knee-piece 44 pivots further around pivot point 46, and fixing point 50 is displaced from a position to the left of the line running through fixing point 54 and pivot point 46 to a position to the right of this line. When fixing point 50 is situated on the line through fixing point 54 and pivot point 46 - this position also being designated as 'dead point' or 'transition point' - the moment arm of the moment of force exerted by spring 52 on knee-piece 44 is equal to zero, whereby the moment is also zero. As a result the moment changes sign when the fixing point passes over this imaginary line.

The moment exerted by knee-piece 44 on flush pipe 36 will, together with the buoyancy of flush pipe 36, exert an upward force on flush pipe 36. According to Archimedes' law, flush pipe 36 is subjected to an upward force which is increased when float 37 is wholly or partially submerged in the water. Float 37 can be embodied in the form of a bell. When the water level in cistern 2 falls, the part of flush pipe 36 that is submerged in the water will decrease, whereby the upward force exerted on flush pipe 36 according to Archimedes' law decreases. In addition, the water flowing out of cistern 2 exerts a pushing force on flush pipe 2 (translator's note = 36) . At a given moment the downward force which flush pipe 36 undergoes as a result of the force of gravity will be greater than the upward force which flush pipe 36 undergoes according to Archimedes' law and the pushing force, whereby flush pipe 36 will begin to move downward and discharge opening 32 in bottom 12 of cistern 2 will begin to close. In conventional devices a quantity of water will hereby always remain behind in cistern 2.

By arranging opening means according to the present invention which exert an upward force on flush pipe 36, flush pipe 36 also undergoes, in addition to the upward force according to Archimedes' law and the pushing force, an upward force which is applied by the opening means. In the shown preferred embodiment these opening means comprise knee-piece 44 which exerts a moment on flush pipe 36. When the water level in cistern 2 has fallen so far that the upward force according to Archimedes' law and the pushing force in co-action with the upward force exerted by the opening means is insufficient to counteract the downward force being exerted on flush pipe 36 by the force of gravity, flush pipe 36 will begin to move downward and close the discharge opening 32 in the bottom 12 of cistern 2 (figure 4) . Because the opening means have postponed the downward movement of flush pipe 36, the water level in cistern 2 has fallen further than is possible with conventional devices. This is a very desirable property, particularly when use is made of greywater, since when it remains still for a longer period in cistern 2, lightly contaminated greywater can result in undesirable odour nuisance and infection, such as for instance legionella.

In a further alternative preferred embodiment as shown in figure 5 the spring 52 is adapted such that it is able, independently of the upward force exerted by Archimedes' law and the pushing force on flush pipe 36, to hold flush pipe 36 in a position in which the discharge opening 32 is open. A control unit 65 is provided with a time switch which is activated when flushing of cistern 2 begins. After a determined preset period of time the control unit 65 will drive knee-piece 44 via a plunger 66 such that the moment exerted by knee-piece 44 on flush pipe 36 is overcome and flush pipe 36 moves to a position substantially closing discharge opening 32. It is of course also possible for flush pipe 36 to be driven directly by plunger 66.

In a further development of the above described preferred embodiment the device further comprises a sensor 63 which senses the water level present in cistern 2. This sensor replaces the time switch of the previous embodiment. As soon as sensor 63 records that the water in cistern 2 has reached a desired water level or is even wholly empty, this sensor 63 generates a signal to a control unit 65 which drives knee-piece 44 via a plunger 66 such that the moment exerted by knee-piece 44 on flush pipe 36 is overcome and flush pipe 36 can move to a position substantially closing discharge opening 32.

It is noted that in a further preferred embodiment (not shown) the water supplied to cistern 2 is collected in a receiving vessel. This receiving vessel is connected to knee-piece 44 such that the water supplied to cistern 2 is used to overcome the moment applied to knee-piece 44 by spring 52. The receiving vessel is for instance mounted pivotally on cistern 2 and is filled with water flowing into cistern 2, wherein the receiving vessel, when it has taken up a determined volume of water, tips over and herein exerts a moment on flush pipe 36 via a mechanical connection such that the moment exerted by knee-piece 44 on flush pipe 36 is temporarily overcome and flush pipe 36 moves into a position closing discharge opening 32. Because the receiving vessel empties when it tips over, it is - after being moved back with for instance a spring - ready for subsequent use . Because this embodiment provides complete draining of cistern 2 in wholly mechanical manner, no additional energy-consuming measures are required, and this makes the device energetically attractive.

According to an alternative preferred embodiment of the present invention shown in figure 6, the mechanical system is replaced by an electrical system. Arranged in cistern 2 is a sensor 63 which senses the water level in cistern 2 and transmits the sensed water level as a signal via wiring 64 to control unit 65, which controls the opening means. In this alternative embodiment the opening means comprise at least an electromagnet 61 which is connected to the control system and which is adapted to hold flush pipe 36 in an open position subject to a signal received by control unit 65. A magnetic part 62 is also arranged on flush pipe 36 for this purpose . Although they are preferred embodiments of the invention, the above described embodiments are intended only to illustrate the present invention and not in any way to limit the specification of the invention. The rights sought are defined by the following claims, within the scope of which many modifications can be envisaged. It will thus be apparent to skilled person that the inventive concept of the present invention is also suitable for all other liquids, and is therefore not necessarily limited to water.

Claims

1. Device for draining water from a storage tank, comprising: - a closing member which is arranged movably between a first position closing a discharge opening in a bottom of the storage tank and a second position leaving the discharge opening substantially clear; and

- opening means for keeping the second position open during draining of the storage tank.

2. Device as claimed in claim 1, wherein the opening means pass through an unstable intermediate position between the first position of the closing member closing the discharge opening and the second position of the closing member leaving the discharge opening clear.

3. Device as claimed in claim 1 or 2 , wherein the opening means comprise : - a moment-transmitting member which is arranged pivotally on the storage tank and which is connected pivotally to the closing member; and

- tensioning means arranged between the moment-transmitting member and the storage tank.

4. Device as claimed in claim 3 , wherein the moment-transmitting member comprises:

- a first pivot point at which the moment-transmitting member is pivotally connected to the closing member;

- a second pivot point at which the moment-transmitting member is pivotally connected to the storage tank; and - a fixing point at which the moment-transmitting member is connected to the tensioning means; and wherein:

- the points define a plane.

5. Device as claimed in claim 4, wherein the distance between the second pivot point and the fixing point of the moment-transmitting member is smaller than the distance between the fixing point of the moment-transmitting member and the fixing point of the storage tank between which the tensioning means are arranged.

6. Device as claimed in claim 4 or 5, wherein the first and second pivot points and the fixing point have a relative position such that during use a moment exerted on the closing member by the moment-transmitting member changes sign as the closing member progresses through the movement between the first and second position, and vice versa.

7. Device as claimed in any of the claims 1-6, wherein the closing member is a substantially elongate hollow body.

8. Device as claimed in any of the claims 1-7, wherein the tensioning means comprise a spring or an elastic.

9. Device as claimed in any of the claims 3-8, further comprising adjusting means which are adapted to fix the tensioning means in different positions on the storage tank.

10. Device as claimed in any of the claims 3-9, further comprising: - a drive member which is arranged between the storage tank and the moment-transmitting member and which is adapted to move the closing member counter to a moment exerted on the closing member by the moment-transmitting member; and

- a control unit for controlling the drive member.

11. Device as claimed in claim 10, further comprising a sensor for sensing the water level in the storage tank, and wherein the control unit is adapted to control the drive member subject to the water level present in the storage tank sensed by the sensor.

12. Device as claimed in claim 1, further comprising: - a sensor for sensing the water level in the storage tank; and

- a control unit for controlling the opening means subject to the water level present in the storage tank sensed by the sensor.

13. Device as claimed in claim 12, wherein the opening means comprise at least an electromagnet which is connected to the control unit and which is adapted to hold the closing member in an open position subject to a signal received by the control unit.

14. System for the reuse of greywater, comprising a device as claimed in any of the claims 1-13.