FR2771456A1 - Self=priming siphon, e.g. for watering plants or removing pools of water from terraces or swimming pool covers - Google Patents

Abstract

The siphon consists of an inverted U-shaped tube (9) filled with a hydrophilic material and having its descending branch (8) extended by a tube (12) of smaller diameter than the siphon. When the end of the rising branch (10) is immersed in a container (2) of liquid (3) the liquid fills the siphon as far as the upper surface (11) of the liquid. It then continues to rise by capillary action until it passes the top point (30) of the siphon and passes down the descending branch and continues to flow as long as the outlet end of the extension tube (12) lies below the level of the liquid surface. The siphon tube (9) can be made from a supple material so it can be bent to the shape of the liquid container, or it can be rigid or semi-rigid, and it can contain an additional perforated tube inside the hydrophilic material or outside the siphon tube for a faster flow. The extension tube can be between 1 and 6 mm and preferably 4 mm in diameter, and can be equipped with a valve to regulate the flow.

Description

The present invention relates to a self-priming siphon, and more particularly to a device combining capillarity and the siphon, in particular but not exclusively, a device for watering plants from a reserve of water.

Devices for operating on the principle of a water tower are known for watering plants (patents JP 011 24 435 and US 1453 401). Water is taken from the base of the container which must therefore have connections provided for this purpose. The container specially designed for this use, therefore has the disadvantage of having a cost and a bulk.

Devices operating by capillarity are known, for example described in French patent 1,493,029 or in German patent 93 19107, but which give a very reduced flow rate.

There is currently no watering device which combines the following advantages:
Watering
without energy input,
with a flow rate adjustable from 0 to several hundred liters per day,
with easy priming and re-priming,
from any tank (the level of which is higher than
pour point),
with the possibility of seeing the water flowing (which is reassuring for
the user).

The present invention aims to provide all these advantages.

The self-priming siphon according to the invention shown in fig. 2 comprises a tube (9) in the shape of an inverted U which contains a hydrophilic material (15).

The descending branch (8) of the U (9) is extended by a pipe (12) of smaller section than that of the tube (9).

When immersing the rising branch (10) of the U (9) in a liquid (3) as shown in fig. 2, the liquid enters the branch (10) expelling the air which escapes through the open end of the pipe (12).

The liquid arrives at the level (11) where it balances with the level of the liquid contained in the container.

Then, the liquid continues to rise by capillarity, in the hydrophilic material (15).

Once the high point (30) has been reached, the liquid continues to wet the hydrophilic material, descending into the branch (8) of the U.

When the liquid arrives at the inlet of the tube (12) if the latter has a section small enough for the surface tension of the liquid to obstruct its passage, it accumulates in the reservoir (16) thus formed.

When the height of the accumulated liquid is sufficient, so that its pressure is greater than the resistance force due to the surface tension, the liquid is forced to engage in the tube (12) and the diameter thereof being smaller , this results in a liquid column (20) of a greater height, therefore a greater depression.

This column of liquid entrained by its weight descends along the tube (12) and causes a suction which initiates the siphon.

By way of nonlimiting example, an embodiment shown in FIGS. 1 and 2 will be described below.

A rigid plastic tube (9) 50 cm long and 12 mm inside diameter is bent into a U shape.

 It is filled with a hydrophilic material (15).

We put it in the inverted position and we immerse its branch (10) in a container (2)
filled with water.

 The air escaping through the other end of the tube (9), the water rises in the branch (10), up to the level (11).

Then, by capillarity, the water continues to rise to cross the upper part (30) and
descend into the branch (8). When the hydrophilic material (15) is well
wet, the water starts to come out drop by drop through the end (19) of the branch (8) of the tube (9) (Figure 1).

 This device is known and is used for drip irrigation.

This device has the disadvantage of giving a very small flow rate (of the order of t / 4 of
liter per day), because it works only by capillary action and not in a siphon.

However, the device according to the invention can provide hundreds of liters per day,
because it works as a siphon.

Indeed, the invention proposes (fig. 2) to extend the branch (8) of the tube (9) by a pipe (12) with an inner diameter smaller than the diameter of the tube (9), for example 4 mm.

The hose (12) is connected to the tube (9) by means of a plug (17) forming a sleeve, and possibly a tap (14) (FIG. 3) intended to regulate the flow rate.

The tubes used being transparent, we observe the phenomena that occur.

 1 ") When the branch (10) of the U is immersed in water, it quickly fills in its submerged part up to level (11).

 2 ") The water then rises by capillary action and completely wets the hydrophilic material (15) (one can moreover visualize the progress of the water by using a hydrophilic material which changes color when it is wet, or else by coloring the water).

 3) Drops (19) fall from the hydrophilic material and gather at the inlet (16) of the tube (12).

 4) When several drops have fallen, the water begins to descend into the tube (12) in the form of a column of water (20) which descends causing suction.

 5) The water which descends into the tube (12) causes air bubbles.

 6) This air is replaced by water, the level of which can be seen rising in the branch (10) of the tube (9).

 7) When the level of this water reaches the upper level (30), it pours into the branch (8) and feeds the pipe (12) much more abundantly than a simple wick.

 8) It can be seen that the flow rate in the tube (12) becomes high, and depends on the height of fall, because the device then operates as a siphon.

 9) When the system is stabilized in operating mode, it no longer evacuates air bubbles. It is noted that in the descending branch (8) there remains air, which does not have any drawback, because in this branch, the water flows, and the suction part of the siphon does not start until the tube (12 ).

The diameter of the pipe (12) is preferably less than or equal to 6 mm.

Diameters of the order of 2, 3 or 4 mm work very well.

A diameter of 5 or 6 mm is less favorable for the formation of a water column in the pipe (12).

Indeed, the water tends to run off, which has no effect on the priming of the siphon.

This defect can be partly corrected by the choice of the material constituting the tube (12). For example with a slightly frosted internal wall, favoring the attachment of water, thus being able to prevent its runoff.

For a diameter of the pipe (12) less than 2 mm the flow of water is more difficult, and the volume of air sucked being reduced, The priming of the siphon is longer, more random, or even impossible for a diameter less than 1 mm.

Another important characteristic of the invention is that, when the hydrophilic material (15) is wetted (either that the siphon has already been used, or that it has been wetted voluntarily by soaking the device in water), the priming of the siphon is much faster.

Indeed, when the branch (10) is immersed in the liquid, the latter penetrates there and rises to the level (11), expelling the air which was contained therein. This air, escaping through the branch (8) and the pipe (12) carries in it a few drops of water which form columns which accelerate the priming of the siphon. In addition, the time which would have been necessary to wet the hydrophilic material is eliminated since this is already wet.

We can further increase the amount of water retained inside the device thanks to an important feature of the invention which is that the branch (8) of the tube (9) has at its end a bend (32) and a small horizontal part (33) which forms a chamber (34) intended to conserve a reserve of water (35) during the defusing of the siphon (fig. 9 and fig. 10).

Another characteristic is that inside this chamber (34) an extension (35) of the pipe (12) prevents water from coming out when, by manipulating the system, the part (33) is tilted relative to the horizontal. .

 It is interesting that the length of the extension (35) is sufficient to keep enough water in the chamber (34) for it to flow out a little through the pipe (12) during the horizontal reset of part (33).

This water, driven into the pipe (12) by pressure when the part (10) is immersed in the water reserve, gives in its fall an impulse at the start of the siphon (choke effect).

In another variant shown in fig. 12, the tube (31) and the tube (12) are formed from a single continuous tube. A hole (36) is made in this pipe in its part passing through the chamber (34). When, by capillarity through the hydrophilic material,
The water arrives in the chamber (34) and fills it until it reaches the hole (36), it engages in the pipe (12) and initiates the siphon.

With this device, priming of the siphon can be done even in unfavorable conditions.

For example when the level (11) of the liquid is too low compared to the level (30) for priming by capillarity, the siphon can still be primed by immersing the branch (10) partially in water.

In the event of defusing the siphon due to the lack of water in the tank, this characteristic allows rapid re-priming as soon as the water level rises sufficiently. This even after several weeks of dryness, because the water contained inside the tube has very little possibility of evaporating.

Variants
The diameter of the tube (9) must be greater than that of the tube (12), because it must contain the hydrophilic material, and moreover contain sufficient vacuum to allow the water to pass when the siphon is primed.

With a too large diameter, the volume of air to be evacuated is large, which increases the priming time.

Too small a diameter reduces the flow.

A good dimension is 10 mm, because it allows the hydrophilic material to be introduced without over-tightening it.

Indeed, it is advantageous that the hydrophilic material has a diameter slightly smaller than the inside diameter to leave a vacuum promoting a good flow of water when the siphon is in operation.

With a tube (9) with an internal diameter of 10 mm, we carried out the following 2 tests: with the hydrophilic material of 10 mm in diameter, which therefore completely filled the tube, a pipe (12) of 4 mm in diameter and a difference of 80 cm high, the flow is 1.5 liters per hour.

- All other things being equal, the hydrophilic material of 10 mm is replaced by one of 8 mm in diameter, there is then a flow rate of 9 liters per hour.

Through the transparent tube (9) we see the water circulating in the free space between the tube (9) and the hydrophilic material.

In alternative embodiments of the device according to the invention, two paths for water can be defined more precisely (fig. 8).

The wick being surrounded by a flexible and impermeable envelope is introduced into the tube (9) with a clearance between the flexible envelope and the interior of the tube (9). The water therefore circulates in a first path which is the wick enclosed in its envelope; This water moving by capillarity is used to prime the siphon and then when the siphon is primed, the water circulates mainly in a second path which is the space delimited by the interior of the tube (9) on the one hand and the outside of the flexible envelope on the other hand ,.

The priming time of the siphon depends inter alia on the amount of air to be eliminated in the rising branch (8) of the pipe (9). It is therefore advantageous for this quantity of air to be as small as possible, so it is better to delimit the volume of the path which is used for the flow of the sucked water.

To do this, in another variant, a tube (31) is used with a diameter substantially smaller than the inside diameter of the tube (9) and which is placed inside the tube (9), over the entire length of the hydrophilic material. The hydrophilic material filling the rest of the void between the tube (9) and the tube (31).

In the example shown in fig. 9, the tube (9) has a diameter of 10mm, and the tube (31) has a diameter of 4mm, equal to that of the tube (12). The tube (31) is thus capable of providing the flow necessary to feed the tube (12), while having a small interior volume.

The hydrophilic material occupies the space between the 2 tubes (9) and (31), thus the quantity of air to be eliminated is reduced, hence faster priming. In this device, a space (32) can be provided at the inlet of the tube (9) between the plug (17) on the one hand and the hydrophilic material and the pipe (31) on the other hand. This is to allow the water to feed the 2 paths.

To avoid the risk of obstruction of the pipe (31), the plug (17) can be replaced by a grid or a foam pipe.

In an alternative embodiment, the hydrophilic material (15) can be a granular material such as sand.

To allow water to pass, this granular material should only be slightly compacted. As a result, it can move inside the tube (9), which produces an empty space, and the water does not cross this discontinuity.

To avoid this drawback, an important characteristic of the invention is that the sand is stabilized inside the pipe thanks to a structure which keeps it in place.

In the embodiment shown in fig.4, the sand is stabilized by a semi-rigid mesh tube (for example plastic) with meshes between 2 and 6 mm introduced inside the stock (9).

However, other devices can be used, for example an internal wall of the tube made rough, or coated with studs (fig; 6), projections, or grooves.

 It is advantageous that the tube filled with sand is transparent in order to be able to check whether it is well filled with the granular material.

In the case of FIG. 5, the granular material is stabilized by an element (15) of semi-rigid plastic formed from a strip which has been twisted, and which is then introduced into the tube.

This twisted strip is flexible enough to be able to be inserted into the butt and follow its curvatures.

The strip of Figure 5 has a width of 10 mm. It is made with a thermoplastic which is twisted hot to obtain a helical shape with a pitch equal to 16 mm.

 It is inserted inside a stock with an internal diameter of 12 mm. There is a slight clearance between the edges of the twisted strip (15) and the inside of the tube. The granular material is then easily introduced inside the device because it rotates around the spiral.

The pipe forming the butt of the previous examples is closed at its two ends by hydrophilic filters, for example a foam pad 16 whose channels are smaller than those of the smallest grains of the granular material.

These hydrophilic filters are held in place by plugs (17) having at their center an opening (18).

The opening of one of the two plugs is of a size compatible with the valve (14) which fits into it.

Since it is advantageous, when the siphon is defused, to keep as much water as possible inside the pipes, in order to speed up the re-priming, the tube (9) is closed at its ends by plugs (17) comprising only a hole with a diameter equal to that of the tube (12) (Figure 3).

The self-priming siphon object of the invention is used in many cases where there is a need to bring a liquid contained in a container to one or more other distribution points.

The siphon according to the invention is intended for watering plants, for example from a constant level tank, flush type - the flow rate being adjusted by means of the tap (14) from zero to several hundred liters per day, depending on the amount of plants to water.

The end (6) of the pipe through which the water flows can be extended by a porous pipe which can be empty, or filled with sand. Thus the flow will not be at a single point, but over the entire length of the porous pipe. This will be used for watering elongated containers, such as planters.

The porous pipe can be made of textile or rubber so as to be flexible.

Claims (5)

 CLAIMS 1 - Self-priming siphon characterized by the fact that it consists of an inverted U-shaped tube inside which is hydrophilic material, the U-tube being extended at its downward part by a pipe significantly smaller in diameter. 2 - Siphon according to 1, characterized in that the liquid, by capillary action crosses the high point of the U-shaped tube, then descends to the tube of smaller diameter to form a column which, driven by its weight causes a priming suction the siphon. 3 - Siphon according to 1 or 2 characterized in that 2 separate paths are provided for the circulation of water  a path containing the hydrophilic material in which the water circulates by capillarity;  a free path in which most of the water flows when the siphon is primed. 4 - Siphon according to 3 characterized in that the free path is constituted by the space defined between the internal wall of the tube (9) and the external wall of a sealed envelope which surrounds the hydrophilic material. 5 - Siphon according to 3 characterized in that the free path is constituted by a pipe of diameter significantly smaller than that of the pipe (9), and circulating inside the hydrophilic material.