EP1629163A2

EP1629163A2 - Water circulation unit with increased throughput for swimming pools, and filter unit comprising the same

Info

Publication number: EP1629163A2
Application number: EP04742586A
Authority: EP
Inventors: Joel Queirel
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-05-28
Filing date: 2004-04-27
Publication date: 2006-03-01
Anticipated expiration: 2024-04-27
Also published as: DE602004002593D1; ES2273275T3; US7311821B2; WO2004109042A2; EP1629163B1; WO2004109042A3; DE602004002593T2; ATE340906T1; US20060289344A1

Abstract

A water circulation unit includes an ejector ( 142 ), a convergent, and a pipe ( 146 ) which is arranged in the extension of the convergent. The ejection axis practically merges with the symmetry axis of the convergent, the two axes forming a common axis of the unit, and the distance between the water outlet of the ejector ( 142 ) and the downstream section of the convergent is between 0.4 and 1.6 times the length of the convergent. A guiding region is located just upstream of the upstream section of the convergent following the common axis, at least up to the water outlet of the ejector ( 142 ) when the outlet is located outside the convergent, the region ensuring that the water is essentially symmetrically guided around the common axis during the operation of the ejector. In a filter unit, a cartridge ( 154 ) is arranged around the water circulation unit.

Description

The present invention relates to a water circulation unit with multiplication of flow for swimming pool, in particular intended for a fixed or mobile group of filtration and pool maintenance, a pool cleaning and broom and even a pool cleaning robot. The invention essentially implements, for a multiplication of flow, a system in which an ejector projects a stream of water into a convergent.

Attempts have already been made to use a flow multiplication effect by spraying a stream of water directed towards a nozzle, an orifice or a cone to ensure the entrainment of the water and thus obtain a high flow rate of water circulation. . Document US Pat. No. 4,501,659 thus describes an apparatus intended to circulate the water of a swimming pool so that it is filtered. As shown in Figure 1 which reproduces a figure from this document, the upper part of the device has a filter and the lower part of the device is connected to a pressurized water supply and has a nozzle facing an orifice in a wall placed opposite. A convergent can be placed in front of the ejector. This is arranged towards the bottom of the device. The water which has passed through the filter approaches the ejector on one side of it and changes direction to pass through the convergent. The flow multiplication factor obtained is relatively small, and never exceeds 2.5.

The document US Pat. No. 4,826,591 also describes a filtration installation for a swimming pool, represented in FIG. 2 which reproduces a figure of this document, in which a pump circulates a stream of water from the swimming pool in a filter. Before returning to the pool, the water passes through an ejector placed in front of a convergent so that the water which has circulated in a basket connected to a "skimmer" is sucked by the convergent. In this system, the flow obtained by multiplication is not used for circulation in a filter, but only in a basket for stopping debris such as leaves. As in the previous document, the ejector and the convergent are placed near a lower surface of a space at the upper part of which is housed the basket. As indicated by the arrows, the water descends towards the entrance of a horizontally arranged convergent and changes direction. Although the body of this document does not indicate the multiplication ratio obtained with such a system, the values indicated for the different dimensions correspond to a reduced multiplication factor, certainly not exceeding 2.5.

The document US Pat. No. 5,785,846 also describes an installation, represented in FIG. 3 which reproduces a figure of this document, in which a pump feeds an ejector which projects a stream of water towards a duct aligned opposite it and arranged in a chamber delimiting a rounded convergent at the entrance of the conduit. The suction effect created by the ejector in the convergent is used for the suction of water which has circulated in a filter and which arrives by a conduit opening laterally into the chamber surrounding the ejector. As shown in this figure, the water stream from the filter arrives from one side of the ejector and must undergo a 90 ^° change of direction to be drawn towards the outlet duct. Although the document does not give any value for the flow multiplication factor, the very large asymmetry of water intake certainly limits the flow multiplication factor to a value well below 2.5.

The document WO 02/086 259 describes a set of water circulation with flow multiplication, a part of which is represented in FIG. 4 which reproduces a figure of this document, which gives a multiplication factor greater than 2.5, and which can even exceed 3. This set of multiplication of flow includes a convergent, a neck and a divergent, and water under pressure is injected in a direction parallel to the internal surface of the neck by a slot arranged at the periphery of the collar. This system is limited to the injection of water into the neck and, given the large length of the slit formed around the neck, this slit must be very narrow; it is found in practice that it is easily shut off, if suitable precautions are not taken so that it does not shut off.

Document WO 03/062 561, which is only to be considered in the context of the invention under article 54 (3) of the EPC, describes an improvement to the system considered in the previous document. As indicated in FIG. 5 which reproduces a figure from this document WO 03/062 561, this system comprises a convergent assembly, neck and diverging element comprising an ejector disposed at the inlet of the convergent and a second ejector disposed in the collar. This system therefore combines a double injection first by an ejector in the axis of the convergent, the neck and the divergent, and then by the neck ejector. In addition, this document indicates that the upstream ejector placed on the axis of the convergent can be located inside a Kaplan elbow intended to allow obtaining a high rate of flow multiplication. As this figure indicates, a flow of 10 m ³ / h, introduced by halves into the upstream ejector and into the throat ejector, gives an output of 30 m ³ / h, that is to say say that the flow multiplication ratio is equal to 3.

We realized that, in the application concerned by the aforementioned documents, that is to say the circulation of water with flow multiplication for swimming pools, it was possible to obtain flow multiplication reports well greater than 3, of the order of 10 and even more by using particularly simple technical means.

We will now describe, with reference to FIGS. 6A to 6D, experiments which have been carried out to demonstrate the effectiveness of the simple technical means implemented according to the invention.

Was placed inside a swimming pool, at a distance from the surface, the bottom and the walls, an ejector 110 intended to direct horizontally a water flow of 2 m ³ / h at a pressure of 2 bar. The speed of the water at the outlet of the ejector was around 17 m / s. In a horizontal position centered on the axis 112 of the ejector, an element consisting of a convergent 114 and a conduit has been placed cylindrical 116. The section of the convergent and that of the duct were circular, from an upstream section of the convergent to a downstream section thereof, up to an outlet section of the duct, so that the assembly formed a surface of revolution. The ejector outlet port was placed in the plane of the upstream section of the convergent.

In the experiment of FIG. 6A, the duct 116 connected to the convergent 114 had a length equal to 40% of the length of the convergent 114. In the experiment of FIG. 6B, the duct part 16 had been doubled and extended d 'a divergent, so that the duct 118 had a length equal to 1.75 times that of the convergent 114. Finally, in the experiment of Figure 6C, the duct 118 of Figure 6B had been extended by a cylindrical duct of length equal to 1.25 times the length of the convergent, so that the conduit 120 had a total length equal to 3 times that of the convergent 114. The section at the part of smallest section, that is to say at the level of the cylindrical duct part 116, was 57 cm ³ . The ejector 110 was supplied with water with a flow rate of 2 m ³ / h at a pressure of 2 bar, and the flow rate and the speed at the outlet of the duct 116, 118 or 120 were measured. It was found that in the case of FIG. 6A, a flow rate of 12 m ³ / h was obtained, in the case of FIG. 6B a flow of 21 m ³ / h and in the case of FIG. 6C a flow of 24 m ³ / h. It can therefore be seen that flow multiplication factors of 6, 10.5 and 12 are obtained respectively. These factors are much higher than those obtained with the devices of the prior art. To clarify these results, experiments were then shown diagrammatically in FIG. 6D. The device was similar to that of FIG. 6B, but the ejector 110 was placed in three positions 110A, 110B and HOC, the position 110B corresponding to the position indicated in FIG. 6B, the position 110A being outside the converge at a distance equal to 45% of the length of the convergent, and the HOC position corresponding to a position inside the convergent, at 45% of the length of this convergent. In the three cases, a multiplication factor practically unchanged, between 10 and 11, was obtained, with the accuracy of the measurements.

It can therefore be seen that, with the extremely simple means shown, it is possible on the one hand to obtain very high flow multiplication factors, and on the other hand to obtain these high factors in a manner which leaves great adjustment margin of the elements used in the longitudinal direction. Additional experiments were then carried out to determine why it was not possible to obtain high multiplication factors in the devices of the prior art. ^• It s then realized that when the axis of the ejector is not aligned with the axis of the convergent and conduit, the multiplication factor decreased significantly. We also realized that any asymmetrical arrangement at the level of the entry of the convergent caused a strong reduction of the multiplication factor. Thus, under the conditions of implementation in the pools considered (volume of approximately 20 to 200 m ³ ), that is to say under conditions in which it is necessary to obtain a relatively high flow rate of a few meters cubes at a few tens of cubic meters per hour (for example 5 to 50 m ³ / h), with a relatively high speed of the water (for example 0.1 to 2 m / s), a primordial factor for obtaining of a high multiplication factor is the circulation of water symmetrically at the outlet of the ejector and the inlet of the convergent. In the experiments described with reference to FIGS. 6A to 6D, we took the precaution of placing ourselves inside a large body of water in order to be able to consider it as infinite around the ejector and the inlet of the converge. The water could therefore exhibit behavior with perfect symmetry at the level of the ejector and the convergent. As soon as an asymmetry is introduced, the circulation of the water is greatly disturbed and the kinetic energy of the current projected by the ejector dissipates quickly as soon as it enters the converge and even before by disturbing the flow of water.

Among all the above documents, only the fifth partially corresponds to the conditions according to the invention. In fact, according to this document WO 03/062 561, an ejector is arranged upstream of a convergent and, at the inlet of the convergent as around the ejector, good symmetry of the water circulation is obtained thanks to the use of a Kaplan elbow. However, the device described in this document does not suggest the invention, because on the one hand there is always an injection of fluid at the neck and on the other hand the alignment of the ejector on the axis of the convergent-col- divergent was not properly assessed, as demonstrated by the results obtained (multiplication factor limited to 3).

The invention relates to the implementation of these characteristics for obtaining a high multiplication ratio; it allows the use of low flow pumps to obtain both a large circulation flow, filtration of a high volume of water, and sufficient agitation of the water. a swimming pool so that particles cannot settle, that the bottom of the swimming pool remains clean and that its cleaning is greatly reduced. More specifically, the invention relates to a water circulation multiplication assembly for swimming pools, of the type which includes a water inlet; The assembly includes an ejector connected to the water inlet and having a water outlet intended to spray water along an ejection axis, a convergent having an axis of symmetry and a section perpendicular to this axis which decreases from an upstream section to a downstream section, and having a length between the upstream and downstream sections, a conduit arranged in the extension of the convergent to which it connects without internal discontinuity to the downstream section of the convergent, the conduit having a length between the downstream section of the convergent and an outlet, the section of the conduit practically not decreasing along its length, the length of the conduit being at least equal to one third of the length of the convergent, the ejection axis being practically coincident with the axis of symmetry of the convergent, and the two axes forming an axis common of the assembly, the distance between the water outlet of the ejector and the downstream section of the convergent being between 0.4 and 1.6 times the length of the convergent, and a guide space arranged just upstream from the upstream section of the convergent along the common axis, and at least up to the water outlet of the ejector when the latter is outside the convergent, this space ensuring the guiding of water in a substantially symmetrical manner around the common axis.

Preferably, the axis of symmetry of the convergent is an axis of rotation symmetry. In an advantageous embodiment, the common axis is an axis of revolution of the convergent and of the conduit. In a particularly advantageous embodiment, the convergent is a truncated cone having a circular director and whose angle of the generator with the axis is between 10 and 15 ^° .

Preferably, the conduit has a length greater than 1.7 times the length of the convergent and preferably greater than 3 times this length.

Alternatively, the conduit also includes a divergent section.

It is advantageous for the outlet section of the pipe to have a value such that the average speed of water leaving the pipe is greater than 0.1 m / s, in particular 0.3 m / s, and preferably between 0.5 and 2 m / s.

Preferably, the flow rate at the water inlet of the ejector is greater than 1 m ³ / h. In one embodiment, the assembly further comprises a pump intended to supply the water inlet.

The invention also relates to a filtration and maintenance group for swimming pools, which comprises a set of water circulation according to the preceding paragraphs, and a filtration device.

In a first embodiment, the filtration and maintenance group is intended to constitute a fixed group in a swimming pool installation.

The aforementioned document WO 02/086 259 describes a filtration method in which a flow multiplier is incorporated in a pumping assembly arranged downstream of the filtration assembly. In this way, the filtration assembly operates by suction, unlike a sand filter which operates under pressure.

In this embodiment, valves and pipes connected to the pumping assembly allow, for the maintenance of a swimming pool, the use of a robot, requiring a low flow rate at high pressure, and a brush intended to pick up debris and dirt.

The use of a vacuum cleaning pool brush in known systems requires closing the filtration and pumping circuit by operating at least one valve, and opening a brush circuit by opening d '' at least one other valve. However, the brush is not a simple device, since it must include a retaining assembly for the debris and dirt collected so that it does not reach the associated pumping assembly. We also know the drawbacks associated with defusing pumping systems due to the almost inevitable introduction of air during the commissioning of the brush.

The use of the broom in a swimming pool is therefore inconvenient, since it requires relatively complex operations and relatively large specialized equipment.

In the first embodiment, the invention relates to a filtration and maintenance group for swimming pools in which the use of a broom is extremely simple.

It does not require the operation of any valve and is only carried out with an accessory of simple construction, thanks to the use of the resources of a filtration group having particular characteristics. More specifically, in the first embodiment, the filtration and maintenance group, which is intended to constitute a fixed group in a swimming pool installation, comprises a pumping assembly which itself comprises the circulation assembly according to the invention, disposed between an inlet opening placed partially above and below a nominal filling level of the swimming pool, and an outlet opening disposed at or near the nominal level, and an assembly filtration arranged between the inlet opening and the pumping assembly.

Preferably, the guiding space of the circulation assembly is delimited by a Kaplan bend connected without discontinuity to the upstream section of the convergent.

In an exemplary embodiment of a filtration group suitable for the use of a suction device used as a cleaning brush, the group further comprises a shutter element and connector, the shutter part being intended to be placed upstream the filtration assembly to prevent direct communication between the inlet opening and the filtration assembly, and the fitting portion providing direct communication between a flexible tube and the filtration assembly; a bypass duct connects a first location, arranged upstream of at least part of the filtration assembly, to a second location, arranged downstream of the filtration assembly and upstream of at least part of the pumping assembly and to which there is a suction, and the flexible tube has a sufficient length so that its end opposite to the end connected to the element forming a plug and connector can be moved to any point of the pool, and a sufficient section to vacuum the debris and dirt present, possibly sucking a large quantity of air without causing a malfunction. It is then advantageous for the filtration assembly to comprise at least two stages, a first coarse filtration stage and a second fine filtration stage, for the obturator and connector element to be arranged in upstream of the coarse filtration stage, and that the first location to which the bypass duct is connected is between the two stages. Preferably, the first filtration stage consists of a removable basket having a large useful surface with orifices of dimension between 0.1 and 0.5 mm. Preferably also, the section of the bypass duct is much smaller than the inlet section of the converging nozzle of the circulation assembly. Preferably, the bypass duct is connected to the filtration assembly and to the pumping assembly near the nominal filling level of the swimming pool, and the pumping assembly sucks the water leaving the filtration assembly. at a level far below the nominal filling level of the pool.

Preferably, the filtration unit further comprises a duct having a first end intended to be connected to a drain at the bottom of the swimming pool, and a second end connected upstream of the circulation assembly, the duct being provided with a valve arranged near its second end.

Preferably, the filtration group also comprises a shutter of the inlet opening which allows the evacuation of all the water from the filtration and maintenance group by the pumping assembly, to place the group in wintering conditions.

Preferably, the pumping assembly which sucks the water leaving the filtration assembly comprises a double pump driven by a single electric motor, and comprising a low pressure and high flow rate pump which feeds the circulation assembly and a high pressure, low flow pump.

Preferably, the outlet opening disposed at or near the nominal level has an axis inclined relative to a normal to the wall of the pool at its location, so that the projected water has a component causing circulation rotating in the pool. In a second embodiment, the filtration and maintenance group is intended to constitute a mobile filtration group for a swimming pool installation, in which the filtration device is a filter practically centered on the common axis.

In a variant, the filter is cylindrical and is in the form of a cartridge surrounding the guide space of the circulation assembly, and the convergent and the conduit are placed essentially in the extension of the cartridge.

In another variant, the filter is cylindrical and is in the form of a cartridge placed essentially around the guide space, the convergent and the duct.

In a third embodiment, the filtration and maintenance group is intended to constitute a mobile filtration group for a swimming pool installation, in which the filtration device and the circulation assembly are arranged in a frame provided with a temporary fixing device to a swimming pool wall. In a first variant, the group includes a water inlet pipe connector intended to be connected to a water inlet.

In a second variant, the group comprises an electric pump supplying the ejector. Preferably, the entire filtration and maintenance group is ballasted so that it can float in an orientation such that a water inlet orifice and a water outlet orifice are close to the surface. water on which the mobile unit floats. In a fourth embodiment, the filtration and maintenance group is intended to constitute a swimming pool cleaning brush.

We already know, for cleaning swimming pools, on the one hand robots and on the other hand brooms. We call a "robot" a cleaning device that can operate without the presence of any operator, and "broom" a device moved by an operator. A robot differs from a broom in that it comprises a displacement device intended to allow it to move to the bottom of a swimming pool.

A cleaning broom, sometimes called a "leaf collector", comprises a body provided with a long handle, usually telescopic, handled by an operator from the edge. Such a broom comprises a body having a lower part close to the bottom, a suction device, having an inlet for pressurized water and a vertical duct starting perpendicularly from the center of the body and delimiting, at the lower part, an inlet. of water and, at the top, a water outlet, and a filter attached to the top and intended to receive contaminating materials, mainly leaves.

A cleaning robot has a body fitted with a propulsion device (wheels, chains, tracks, belts, water jets, etc.). The propulsion device is driven by a motor device so that it moves the body on a pool floor, with the possibility of changing direction at the limits of the bottom. The body includes a suction device, having a pressurized water inlet and a vertical conduit, sometimes in the form of a venturi, into which pressurized water is introduced so that it causes the circulation of an ascending current. of water from the pool to the filter which is attached to the upper part of the duct. Such a robot further comprises a cleaning accessory formed of a flexible tube provided with bodies intended to rub against the bottom of the swimming pool in order to detach contaminating materials therefrom.

Swimming pool installations create, for the supply of pressurized water supply to a robot or a cleaning broom, and sometimes other accessories, a stream of water of moderate power (from around 3 to 0.5 m ³ / h at a pressure of 1 to 5 bar, most often from 2 to 3 bar, the flow rate of the same pump decreasing when its pressure increases).

A brush has all this power, around 100 W, for the sole suction function. A robot has this same power, but, in a robot, this current of water is distributed in substantially equal amounts between the propulsion functions of the robot, creation of an updraft in the vertical duct, and drive of the cleaning accessory. It can thus be seen that the function of creating an ascending current does not have great power. For this reason, cleaning a swimming pool requires many hours of robot operation, and it is therefore often done at night. As the robot's water supply requires at least one pump to operate, a noise problem may arise. Above all, this low power available for the updraft does not give a sufficient speed to detach the contaminating materials which cling firmly to the swimming pool, so that the cleaning accessory is necessary.

It is therefore understandable that a cleaning broom has advantages of simplicity, efficiency and speed compared to a robot. However, known brushes pose a number of problems. First, the known brushes do not have good stability. In order not to tire the operator unduly, their body must be relatively light. As soon as the filter, which is in the high position, begins to fill with sheets, these tend to tilt and tilt the filter to one side. Even if the weight of the picked up material is not important, the filter tends to tilt the broom on the side towards which the bag is offset. If this tendency to tilt is oriented in one axis of the telescopic handle of the broom, the operator only needs a moderate effort to compensate for the effect observed. However, if the bag tends to tilt laterally relative to the axis of the handle, the operator must exert on the handle of the torsional forces more and more important, and undergoes significant fatigue. Some telescopic handles do not allow the application of such a torque, so that the broom must be taken out of the pool very frequently to empty the bag. Another disadvantage of these brushes is that, when the bottom of the swimming pool has a convexity, they tend to be supported by their central part on this convexity, and significant efforts are then necessary to dislodge the brush. It is common for swimming pool bottoms to have such convexities, in particular at transitions between different parts of the pool bottom having different depths.

Another disadvantage of these brushes is that they include an ineffective conduit for the formation of the ascending stream of cleaning water, and their cleaning effect is not very powerful.

In this fourth embodiment of the invention, a brush has great power, great mobility and great stability.

The large power is obtained thanks to several characteristics which are firstly the high flow multiplication factor obtained thanks to the water circulation assembly according to the invention, secondly the large extent over which a rapid current of water circulates on the bottom of the swimming pool, this rapid current of water being obtained by the formation of a thin layer of liquid in the guide space on the lower surface of the brush, and thirdly the formation of a peripheral skirt which delimits the zone d action of the powerful current formed.

The great mobility is obtained by using wheels arranged so that they avoid any direct contact of the body with the bottom of the pool on a convexity.

The great stability is obtained by lowering the center of gravity of the broom due to the accumulation of contaminating materials picked up at a low location of the broom, either directly on the base of the body, or near the lower part of the broom.

More specifically, in the fourth embodiment, the filtration and maintenance group is intended to constitute a pool cleaning brush; in this case, the guiding space of the circulation assembly is delimited by a plane substantially perpendicular to the axis common passing through the upstream section of the convergent and through a surface substantially parallel to this plane and arranged more upstream.

In an exemplary embodiment, the group comprises a body having a base, the lower surface of which, intended to be close to a swimming pool bottom, constitutes practically the plane substantially perpendicular to the common axis which is intended to be practically vertical, a nozzle for fixing a handle to the body, and a filter bag surrounding the upper part of the circulation assembly; the filtration device is then fixed to the body at the lower part thereof.

Preferably, the filtration device is fixed to the base. In a first variant, the filtration device is a filter bag which has orifices of dimension greater than 40 μm, and preferably of the order of 60 μm.

In a second variant, the filtration device is a filtration cartridge. Preferably, the filtration device has an air exhaust valve at its upper part.

In an advantageous example, the lower surface of the base has two substantially parallel sides which are provided with wheels. Preferably, the wheels are arranged in two parallel lines, and each line comprises at least three wheels.

Preferably, the space between the edges of the base and the inlet of the circulation assembly on the lower surface has a large extent and a low height.

Preferably, the edges of the lower surface of the base are provided with a skirt, and the skirt is advantageously formed by a member chosen from a flexible flap and bristles. Other characteristics and advantages of the invention will be better understood on reading the description which will follow of exemplary embodiments, made with reference to the appended drawings in which: Figures 1 to 5 are simple reproductions of a significant figure of each of the five aforementioned prior art documents, and they have been described previously; FIGS. 6A to 6D are diagrams which have already been described for the explanation of the means of the invention; FIG. 7 is a diagram of a fixed filtration group for swimming pools implementing the principles of the invention; FIG. 8 represents an example of use of the filtration group of FIG. 7 in an application to a pool cleaning brush; Figure 9 is a perspective view of an assembly as shown in Figure 7; FIG. 10 is a partial section of a swimming pool cleaning brush comprising a water circulation multiplication assembly according to the invention; Figure 11 is a perspective view from below of the brush of Figure 10; Figure 12 is a perspective view from above of the brush of Figures 10 and 11; Figure 13 is a perspective view from above of a mobile filtration unit comprising a water circulation assembly according to the invention; Figure 14 is a perspective view of the rear of the group of Figure 13; Figure 15 is a view with parts broken away from the group of Figures 13 and 14, showing how the invention is implemented in a movable assembly; and FIG. 16 is a sectional view of a mobile filtration unit which is particularly simple and effective according to the invention.

We have already described, with reference to FIGS. 6A to 6D, the essential operating characteristics of the flow multiplication circulation assembly according to the invention.

We now describe examples of embodiment corresponding successively to the first, fourth, third and second embodiments, with reference to Figures 7 to 9, 10 to 12, 13 to 15, and 16 respectively.

FIG. 7 generally represents a filtration and maintenance group for swimming pools in the first embodiment of the invention. This group 10 is intended to be placed essentially below the nominal level of the water in the pool, this level being identified by the reference 12 in FIGS. 7 and 8.

The main elements of this filtration group are, on the one hand, a filtration assembly 14 and, on the other hand, a pumping assembly 16.

More specifically, the filtration assembly 14 is connected at its upper part to a space which opens into the swimming pool basin by an inlet opening 18, formed by an element known in the art under the name of "skimmer" and which can be closed by a plug or a shutter, not shown. The upper space also has an upper opening 20 which is normally at ground level around the pool and which is closed by a hatch.

The filtration assembly 14 preferably comprises at least two stages, a first stage 22 for coarse filtration and a second stage 24 for fine filtration.

Preferably, the coarse filtration stage 22 allows particles of dimension less than a fraction of a millimeter to pass through, and operates according to a screen filter principle. For example, this first filtration stage 22 consists of a basket advantageously formed of a fabric with holes of 0.1 to 0.5 mm, for example 0.3 mm, injection molded between ribs of plastic.

The second fine filtration stage 24 comprises a cylindrical filter made up of a sheet of an accordion-pleated nonwoven, held between two circular flanges and surrounded in a variant by an external nonwoven. This second filtration stage 24 constitutes in this variant a double stage, on the one hand formed by the outer nonwoven, having the role of a deep filter, and on the other hand by the accordion pleated nonwoven, having the role of a surface filter, the fineness of filtration of which is significantly greater than that of the outer nonwoven.

An advantageous characteristic of the filtration assembly shown in FIG. 7 is that the outlet of the filter 24 is located at the lowest point of the group and is connected by a conduit 26 which rises to the nominal level of the water in the pool. .

The pumping assembly 16 comprises a pump 28 and a flow multiplication assembly 30. The pump 28 is advantageously of the type described generally by the application for French patent No. 02.13 384. This pump comprises a motor 32, advantageously of electric type, which drives the rotor of a first pump 34 at high flow rate (for example 14 m ³ / h) and low pressure (for example 1.4 bar) whose inlet is connected to the conduit 26 at the most bottom of the filtration unit, that is to say near the outlet of the filtration assembly 14. The total flow rate of the pump 34 (for example 14 m ³ / h) is distributed between a first outlet 36 (by example 12 m ³ / h) which is connected to the flow multiplication assembly 30 and a second outlet 38 (for example 2 m ³ / h) which is connected to the second pump 40. This pump 40 raises the pressure of the liquid received (for example from 1.4 bar) and feeds a line 42 which allows the operation of a brush or a cleaning robot (working for example at 2.5 bar).

The outlet 38 shown in the form of a separate pipe is however preferably constituted by an assembly placed all around the electric motor 32 to cool the latter. The flow multiplication assembly 30 comprises a converging nozzle then a diverging nozzle, and an ejector 44 placed just upstream of the converging nozzle. Thus, for a flow rate of 12 m ³ / h at a pressure of 1.4 bar transmitted by the ejector 44, the flow rate at the outlet of the flow multiplication assembly 30 is of the order of 36 m ³ / h, this flow being transmitted to the basin by the outlet opening 48. When the ejector 44 is adapted to the flow and to the pressure of the second pump 40, for a flow of 2 m ³ / h at a pressure of 2.5 bar transmitted by the ejector 44, the flow rate at the outlet of the flow multiplication assembly 30 is of the order of 30 m ³ / h, this flow rate being transmitted to the basin through the opening outlet 48. FIG. 8 represents the same filtration group, but provided with an element forming a shutter and connector 50 according to the invention.

The element 50 comprises, on the one hand, a part forming a shutter 52 and, on the other hand, a part forming a connector 54. This part forming a connector is intended for the connection of a flexible tube 56 used as a broom for the swimming pool.

The shutter portion 52 is preferably applied upstream of the filtration assembly and in particular of the first stage 22. For example, this shutter portion 52 is a circular plate provided with lugs allowing it to be locked by rotation, by an effect of bayonet. Consequently, most of the suction from the pump 28 passes through the flexible tube 56. When the tube essentially sucks up water, leaves and other debris, the water circulates normally in the filter, and the leaves and other debris sucked up are stopped by the basket 22 forming the first filtration stage. When the broom is working, it basically sucks up water. According to a characteristic of this embodiment of the invention, when air manages to be introduced into the filtration assembly, by means of the element forming a shutter and fitting, this air can only circulate in the coarse filtration part 22 and not in the fine filtration part 24. In fact, a bypass conduit 58 of small section is disposed between the filtration assembly, at a location between the two filtration stages, and the conduit 26 which joins the flow multiplication set. Thanks to this bypass duct 58, the air sucked in by the flexible tube 56 does not circulate in the fine filtration stage 24, but passes through the duct 58 and is evacuated directly by the flow multiplication assembly. In the extreme, if the water flow rate passing through the filtration stage 24 is lower than the nominal flow rate of the pump 28, the filtration unit tends to almost certain defusing. The bypass conduit 58 therefore has the essential advantage of enabling switching to the brush function by simple positioning of the shutter and connector element 50 according to the invention. More specifically, the use of the "broom" function given by the tube 56 simply requires the removal of the hatch which closes the opening 20 and the installation of the shutter 52 on the filtration assembly. From this moment, the suction is ensured by the flexible tube 56 and continues until the element 50 is removed. At this time, the filtration unit resumes normal operation, with multiplication of the flow. The bypass duct 58 has the auxiliary advantage of allowing the use of the filtration basket 22 to retain debris and dirt, without disturbing the fine filtration stage 24.

The filtration unit 10 shown in Figures 7 and 8 has many other advantages.

First, the inlet opening 18 and the outlet opening 48 are very close to the nominal level 12 of the water in the pool.

Another advantage of the filtration unit is that the pumping assembly is connected to the lower part of the filtration assembly, at the lowest point of the installation. Consequently, when the inlet opening 18 is properly blocked, the pumping assembly allows the group to be emptied, for example for wintering. The section of the bypass duct is very small compared to that of the duct 26. In this way, during normal operation, the flow of water passing through this bypass duct having undergone only the primary filtration is extremely reduced when 'it is water. The ratio of the sections of the conduits 58 and 26 is preferably less than 1/15, for example of the order of 1/25.

According to an advantageous characteristic of the invention, the outlet 48 which leads to the swimming pool, either directly, either by a nozzle, has an axis which is preferably inclined in a horizontal plane relative to a normal to the wall of the pool. This inclination of the axis of the outlet 48 of the water stream is indicated in FIG. 9. In this way, the stream of water with a high flow rate also has a high kinetic energy, transmitted to the pool water with a movement component that promotes closed loop flow at the surface of the pool, and also a mixing of the entire volume of the pool. This closed-loop flow allows circulation of debris and dirt, promoting their capture by suction through the opening 18 of the "skimmer".

The significant energy transmitted to the pool water, which creates a circulation component causing a rotating flow, has the advantage of ensuring excellent mixing of the pool water, and ultimately limiting, even eliminating, stagnation zones.

This stirring effect is demonstrated by turbidity determination tests. In these tests, extremely fine clay is introduced into the pool water, at a rate of 50 g / m ³ of water. The water is then extremely cloudy. The test consists in determining the efficiency of filtration by determining the time necessary for the water to return to a clarity threshold which corresponds to a turbidity index either four times or twelve times lower, using 'a turbidimeter.

It is thus determined that the return to the acceptable turbidity threshold requires less than a day, generally of the order of ten hours, while several days are usually necessary with conventional filtration, without counting the significant formation of deposits. This result is obtained, on the one hand, thanks to the high flow rate obtained with the flow multiplication assembly, for a moderate power of the pump, and, on the other hand, thanks to the stirring effect obtained by the gyration induced by the result of the outlet water current and its orientation, for example 20 ^° relative to normal at the wall of the swimming pool. FIG. 9 represents the major part of a filtration group according to the invention, in perspective view, with in addition a certain number of advantageous characteristics. In particular, it should be noted that the housing of the filtration assembly and of the conduit 26 consists of an assembly produced by a blowing technique, the body containing the filter preferably being a rib in order to have good mechanical strength.

There is an improvement in FIG. 9 according to which a conduit 60 has an upper end on the one hand which opens to the atmosphere and on the other hand which is connected by a valve 62 to a location which is upstream of the flow multiplication set. Its lower end is intended to be connected to a drain at the bottom of the pool. In this way, it is possible to circulate water by vacuum in this conduit at a flow rate of approximately 4 m ³ / h and thus to obtain circulation by a bottom drain of the swimming pool.

Although it has been indicated that the bypass duct is connected between the first and second filtration stages, it can also be placed entirely upstream of this filtration assembly. In this case, debris can pass through the bypass pipe, but as it has a small section, this debris is not very annoying, as long as they do not block this pipe. Any device sufficient to prevent clogging of the bypass pipe is therefore sufficient. In addition, the second end of the duct can be connected at any location where a suction exists, for example at any point upstream of the converging nozzle of the flow multiplication assembly.

The filtration unit in Figures 7 to 9 is well suited for swimming pools with a water volume of the order of 100 to 200 m ³ . When the volume is larger, several groups can be used and can share certain elements, for example a pump. When the volume is smaller, it is advantageous to use a mobile type group, as described later in this specification. In the fourth embodiment, the filtration and maintenance group comprising the circulation assembly of 1 ^• invention is intended to constitute a pool cleaner head. Figures 10 to 12 show different views of this embodiment of the pool cleaning brush according to the invention.

As clearly indicated in FIG. 12, the brush essentially comprises a body 210 and a filter 212 shown in this case in the form of a bag for simplicity of representation but which can be a filter cartridge.

The body comprises a base 214 and a conduit 216 perpendicular to the base 214. The conduit is part of the water circulation assembly according to the invention. The base 214 has wheels 218, in the form of two rows of three wheels in the embodiment shown. A skirt 220, for example formed of a rubber or an elastomer, but which can also be formed of bristles, is disposed at the entire lower periphery of the base 214. The duct 216 has an inlet 222 of converging at the level from the lower surface of the base and an outlet 224 at its upper part. The duct 216 is formed in this case by a convergent, a cylindrical central part 226 and a divergent. A tube 228 ends at the inlet 222 of the convergent by an ejector 230 intended to project an ascending current of pressurized water, transmitted by an inlet connector 232. The connector 232 is intended to be connected by a tube flexible to a pressurized water intake usually arranged at the edge of a swimming pool and giving a flow rate of the order of 2 m ³ / h at a pressure of 1 to 5 bar, for example from 2 to 3 bar.

At its upper part, the base has a collar 236 intended to retain a retaining cord 234 placed at the opening of the filter bag 212 of the brush. Also shown, in Figure 12, a tip 238 comprising an articulated rod 240 allowing the connection of a telescopic handle. Finally, note the presence of a valve 242 at the top of the filter bag 212.

It will be noted in FIGS. 10 and 11 that the base 214 delimits, with the surface on which the brush rests, a space for guiding the circulation assembly of low height and large extent, symmetrical around the entrance to the convergent (see the large base surface surrounding the inlet 222 in FIG. 11). We also note that the skirt 220 leaves a small space only for the passage of water between the base and the bottom of the pool.

Since the entire stream of pressurized water (2 m ³ / h at a pressure of 1 to 5 bar) is transmitted to the ejector 230, and this is placed at the inlet of the convergent, l The suction effect created by the circulation system is very important. The suction water stream must first circulate in the low height and large guide space formed between the lower surface of the base and the bottom of the pool before reaching the convergent. As this space has a low height, the water flows with a high speed and therefore has a significant cleaning effect. This effect is further reinforced at the edges of the broom since the skirt delimits a locally very small space and therefore causes an acceleration of the water which then takes on a high kinetic energy on the bottom of the pool.

This very powerful suction effect is easily demonstrated: the removal of several kilograms of soil thrown to the bottom of a swimming pool requires only a few tens of seconds, and the apparatus allows the suction of stones weighing several tens of grams.

Another characteristic of the cleaning brush shown in FIGS. 10 to 12 is its great mobility. The wheels 218 are mounted on ball bearings, preferably stainless, and as they are arranged on two lines (oriented parallel to the direction of the telescopic handle fixed to the rod 240 of the end piece 238), the base does not come directly in contact with a convexity, because the wheels in the middle of each line come in contact with the convexities and allow easy movement.

A very important characteristic of the brush shown in Figures 10 to 12 is its great stability. Although the body is made of light plastic material and has a low weight, as the filter bag 212 is fixed by a cord 234 of its lower opening around a flange 236 of the base of the body, the contaminated materials sucked up, when they escape through the outlet 224, fall around the duct 216 and come to accumulate on the base all around the latter. As the water flow from the outlet is directed upwards, it tends to center the upper part of the bag, so that leaves and other waste can fall all around the duct on the base. The weight of the contaminated material collected therefore constitutes a kind of ballast which increases the stability of the broom. In practice, the accumulation of contaminating materials can reach the height of outlet 224.

Another advantageous characteristic of the invention is that the filter bag 212 is preferably formed from a fabric having meshes of dimension greater than 40 μm and preferably of the order of 60 μm. Such a mesh size ensures the retention of even small contaminating materials, such as small particles of soil, and therefore quickly ensures the cleanliness of the pool. These meshes are however so small that air cannot escape from the bag through the fabric; a fabric with such a fine mesh cannot therefore be used with a known broom. According to the invention, the filter bag 212, when formed from such a fabric, comprises a valve 242 for exhausting air. Although this characteristic has not been shown, the mop may also include, in a known manner, a cleaning accessory in the form of a flexible tube provided with members intended to rub against the bottom of the pool to separate the materials strongly attached. Such an accessory can be easily mounted at the connector 232 or at another location of the tube 228. However, this accessory is generally not necessary, unless the pool has not been used for a very long time without undergoing any cleaning, so that particularly resistant dirt may have adhered to the bottom of the pool. Although the base has been described with a flange 236 intended to retain the bead 234 from the opening of the filter bag 212, the flange may be placed on the duct near the inlet, so that the contaminating materials constitute a ballast. Although a filter bag 212 has been described, it can advantageously be replaced by a filter cartridge, preferably fixed to the base and which thus increases the stability of the latter, as shown in FIG. 17 described in the following. The brush that has just been described, when it is fitted with a filter cartridge 250 as indicated in FIG. 17, can also be used as a filtration and maintenance group comprising the circulation assembly according to the invention and intended to constitute a mobile or autonomous group of filtration and maintenance of swimming pool. FIG. 17 represents the brush of FIGS. 10 to 12 turned 180 ^° and placed in a housing 244 provided with water inlets 246 at the level of the surface of the pool and a water outlet 248. The bag has been replaced by a filtration cartridge 250, and the assembly constitutes a mobile or autonomous filtration group.

Thus, the same combined device is used either as a broom or as a filtration unit.

The invention also relates to other mobile filtration units, as indicated in FIGS. 13 to 16.

FIG. 13 represents part of a wall 122 of swimming pool at the upper part of which are supported two hooks 124 which carry a body 126 of mobile filtration unit. The mobile filtration unit has an opening 128 of "skimmer" which feeds a filter body 130 of vertical orientation. Between the lower part of the filter 130 and an opening 132 for evacuating the group's water filtration is arranged a conduit which rises and whose vertical part comprises a convergent 134 then a conduit 136 which, in the example shown, comprises a divergent part. An ejector 138 for the circulation assembly according to the invention is disposed on the axis and in the axis of the duct part 136, at the entrance practically of the convergent 134. In the example shown, the ejector 138 is powered by a water intake 140 present in the wall of the pool.

A lower opening 135 allows the group to be emptied and easily removed from a swimming pool.

When the pool wall has several water intakes, the mobile filtration unit can occupy various locations. In a first variant, one of the hooks 124 (or a swimming pool ladder) can be used for the supply of water (or electricity in the following variant). In this other variant, the group includes a low-flow, high-pressure pump (approximately 2 bar or more), for example of the electrical type, which is mounted on the body 126 and directly draws water from the pool: no connection in no water is needed.

In FIG. 15, the reference 141 designates a three-way valve allowing the supply either of the multiplication assembly (ejector 138), or of a pressurized water intake 139 intended for an accessory such as a brush. of cleaning.

This mobile unit has the advantage of being able to be moved and to be able to be used in particular with above-ground pools which generally have a smaller volume than in-ground pools. It has only light and inexpensive elements and can be easily moved, especially thanks to its handles. In addition, it is easily produced in floating form, and it is preferably ballasted so that it can float in an orientation such that a water inlet orifice and a water outlet orifice are close to the surface of the water on which the mobile unit floats.

In the third embodiment, the filtration and maintenance group comprising the set of circulation according to 1 the invention is also intended to constitute a mobile or autonomous group of filtration and maintenance of swimming pool, but it is even simpler than the group of the second embodiment. FIG. 16 represents such a mobile filtration group.

The apparatus of FIG. 16 comprises an ejector 142 aligned on an axis and connected to a connector 144 allowing a connection to a water supply pipe. A duct 146 having a convergent on the side of the ejector is arranged on the axis of the ejector and is connected to the latter by a small number of thin arms 148, ensuring the support of the convergent while disturbing the water flow between the ejector and the inlet of the convergent. The ejector and the duct 146 are held by two flanges 150, 152 which also support a cylindrical filter cartridge 154. This is advantageously held on the inner side by a grid 156, for example of plastic, and another grid 158 is advantageously arranged outside so that large objects, such as sheets, do not come directly to the filter contact 154.

During the operation of the apparatus of FIG. 16, as soon as the ejector 142 projects a stream of water in the axis of the duct 146, the water disposed all around the apparatus passes through the grid 158 and the filter 154 and comes into the space between the filter 154 and the pipe 146. This water is sucked from the side of the convergent then flows inside the pipe 146.

In tests, the device represented in FIG. 16 was used with a pressure at the outlet of the ejector of between 1 and 3 bar and a flow oscillating between 0.5 and 3 m ³ / h. The speed obtained at the outlet of the conduit was always greater than 0.2 m / s and the multiplication factor was always greater than 10. This mobile group has not only the advantage of being able to be moved and of being able to be used in particular with above ground pools which generally have a smaller volume than inground pools, such as the second group embodiment, but furthermore it is even lighter and less expensive and is very effective.

The advantages of the mobile filtration units of the last two embodiments described are obvious. Thus, a group can be arranged near the location of a swimming pool which is the dirtiest or most convenient to access. The group can only be introduced into the pool when necessary. For example, a single group can be used transported to filter the water of several swimming pools consecutively. No special device, other than a water or electricity supply, is necessary, such as a closed protective space. In addition, thanks to the low weight of each group, several groups can be arranged simultaneously in the same large pool, the time required for filtration. Finally, when the group can float, no anchoring device is necessary.

Claims

1. Water circulation multiplication assembly for swimming pools, of the type which includes a water inlet, characterized in that it comprises: an ejector (110) connected to the water inlet and having an outlet of water intended to spray water along an ejection axis, a convergent (114) having an axis of symmetry and a section perpendicular to this axis which decreases from an upstream section to a downstream section, and having a length between the upstream and downstream sections, a conduit (116, 118, 120) disposed in the extension of the convergent (114) to which it connects without internal discontinuity to the downstream section of the converging, the conduit having a length between the downstream section of the converging and an outlet, the cross section of the duct practically not decreasing over its length, the length of the duct being at least equal to one third of the length of the convergent, the ejection axis being practically coincident with the axis of symmetry of the convergent, and the two axes forming a common axis (112) of the assembly, the distance between the water outlet from the ejector (110) and the downstream section of the convergent (114) being between 0.4 and 1.6 times the length of the convergent, and a guide space arranged just upstream of the upstream section of the convergent (114) along the common axis (112), and at least up to the water outlet of the ejector when the latter is outside the converge, this space ensuring the guiding of water in a practically symmetrical manner around the common axis.

2. Assembly according to claim 1, characterized in that the axis of symmetry of the convergent is an axis of rotation symmetry.

3. An assembly according to claim 2, characterized in that the common axis (112) is an axis of revolution of the convergent and the conduit.

4. Assembly according to claim 3, characterized in that the convergent (114) is a truncated cone having a circular director and whose angle of the generator with the axis is between 10 and 15 ^° .

5. An assembly according to any one of claims 1 to 4, characterized in that the conduit (118, 120) has a length greater than 1.7 times the length of the convergent.

6. An assembly according to any one of claims 1 to 5, characterized in that the conduit (118, 120) also comprises a divergent section.

7. Assembly according to any one of the preceding claims, characterized in that the average speed of water leaving the conduit (116, 118, 120) is greater than 0.1 m / s.

8. An assembly according to claim 7, characterized in that the outlet section of the duct has a value such that the average speed of outlet of the water from the duct (116, 118, 120) is between 0.3 and 2 m / s.

9. Assembly according to any one of the preceding claims, characterized in that the flow rate at the water inlet is greater than 1 m ³ / h.

10. An assembly according to any one of the preceding claims, characterized in that it further comprises a pump intended to supply the water inlet.

11. Filtration and maintenance group for swimming pools, characterized in that it comprises a water circulation assembly according to any one of the preceding claims, and a filtration device.

12. Filtration and maintenance group according to claim 11, intended to constitute a stationary group in a swimming pool installation, characterized in that it comprises a pumping assembly (16) including the circulation assembly, arranged between an inlet opening (20) placed partially above and below a nominal level of filling of the swimming pool, and an outlet opening (48) disposed at or near the nominal level , and the filtration device (14) is arranged between the inlet opening (20) and the pumping assembly (16).

13. Filtration and maintenance unit according to claim 12, characterized in that the guide space of the circulation assembly is delimited by a Kaplan elbow connected without discontinuity to the inlet of the convergent.

14. Filtration and maintenance unit according to one of claims 12 and 13, characterized in that it further comprises an element (50) forming a shutter and fitting, the part (52) forming a shutter being intended to be placed upstream of the filtration assembly (14) to prevent direct communication between the inlet opening (20) and the filtration assembly (14), and the part (54) forming a connection ensuring direct communication between a flexible tube (56) and the filtration assembly (14), and a bypass conduit (58) connecting a first location, disposed upstream of at least part of the filtration assembly (14), to a second location, arranged downstream of the filtration assembly (14) but upstream of at least part of the pumping assembly (16), and to which there is a suction, the flexible tube having a length sufficient for its end opposite the end connected to the element (50) forming a shutter and powerful connector e be moved to any point in the pool, and have a section sufficient to suck up the debris and dirt present, possibly sucking up a large quantity of air without causing any malfunction.

15. Filtration and maintenance unit according to claim 14, characterized in that the filtration assembly (14) comprises at least two stages, a first stage (22) of coarse filtration and a second stage (24) of filtration fine, the element (50) forming a shutter and connector is disposed upstream of the coarse filtration stage (22), and the first location to which the bypass conduit (58) is connected is located between the two stages.

16. Filtration and maintenance unit according to claim 15, characterized in that the first filtration stage (22) consists of a removable basket having a large useful surface with orifices of size between 0.1 and 0.5 mm.

17. Filtration and maintenance unit according to any one of claims 14 to 16, characterized in that the section of the bypass duct (58) is much less than the inlet section of the converging of the multiplication assembly (30) debit.

18. Filtration and maintenance unit according to any one of claims 14 to 17, characterized in that the bypass duct (58) is connected to the filtration assembly (14) and to the pumping assembly ( 16) near the nominal level (12) of filling the swimming pool, and the pumping assembly (16) sucks the water leaving the filtration assembly (14) at a level much lower than the nominal filling level of the swimming pool.

19. Filtration and maintenance unit according to any one of claims 12 to 18, characterized in that it further comprises a duct (60) having a first end intended to be connected to a bottom drain of the swimming pool , and a second end connected upstream of the circulation assembly, the duct being provided with a valve (62) disposed near its second end.

20. Filtration and maintenance unit according to any one of claims 12 to 19, characterized in that it further comprises a shutter of the inlet opening (20) which allows the evacuation of all of water from the filtration and maintenance group by the pumping assembly (16), to place the group in wintering conditions.

21. Filtration and maintenance unit according to any one of claims 12 to 20, characterized in that the pumping assembly which sucks the water leaving the filtration assembly (14) comprises a double pump (28 ) driven by a single electric motor (32), and comprising a pump (34) at low pressure and high flow and a pump (40) at high pressure and low flow.

22. Filtration and maintenance unit according to any one of claims 12 to 21, characterized in that the outlet opening (48) disposed at or near the nominal water level has an axis inclined with respect to a normal to the wall of the pool at its location, so that the projected water has a component causing rotating circulation in the pool.

23. filtration and maintenance group according to claim 11, intended to constitute a mobile group for a swimming pool installation, characterized in that the filtration device is a filter practically centered on one common axis.

24. filtration and maintenance unit according to claim 23, characterized in that the filter is cylindrical and is in the form of a cartridge placed essentially upstream of the converging and surrounding one guide space.

25. Filtration and maintenance unit according to claim 23, characterized in that the filter is cylindrical and is in the form of a cartridge placed essentially around the guide space, the convergent and the conduit.

26. Filtration and maintenance group according to claim 11, intended to constitute a mobile group for a swimming pool installation, characterized in that the filtration device and the circulation assembly are arranged in a frame provided with a temporary fixing device to a swimming pool wall.

27. Filtration and maintenance unit according to claim 26, characterized in that it comprises a water inlet pipe connection intended to be connected to a water inlet.

28. Filtration and maintenance unit according to claim 26, characterized in that it comprises an electric pump supplying the ejector.

29. Filtration and maintenance group according to any one of claims 26 to 28, characterized in that the whole group is ballasted so that it can float with an orientation such as an inlet orifice d water and a water outlet orifice are close to the surface on which the mobile unit floats.

30. A filtration and maintenance group according to claim 11, intended to constitute a swimming pool cleaning brush, characterized in that the guide space of the circulation assembly is delimited by a plane substantially perpendicular to the 'common axis passing through the upstream section of the convergent and through a surface substantially parallel to this plane and disposed more upstream.

31. Filtration and maintenance unit according to claim 30, characterized in that it comprises a body (210) having a base (214), the lower surface of which, intended to be close to a pool bottom, constitutes practically the plane substantially perpendicular to the common axis which is intended to be practically vertical, a nozzle (238) for fixing a handle to the body, and a filtration device (212) surrounding the upper part of the assembly circulation, and the filtration device is fixed to the body (210) at the lower part thereof.

32. Filtration and maintenance unit according to claim 31, characterized in that the filtration device (212) is fixed to the base (214).

33. Filtration and maintenance unit according to one of claims 31 and 32, characterized in that the filtration device is a filter bag (212) having orifices of dimension greater than 40 μm, and preferably l '' order of 60 μm.

34. Filtration and maintenance unit according to one of claims 31 and 32, characterized in that the filtration device is a filtration cartridge.

35. Filtration and maintenance unit according to any one of claims 31 to 34, characterized in that the filtration device has a valve (242) for evacuating air at its upper part.

36. Filtration and maintenance unit according to any one of claims 31 to 34, characterized in that the lower surface of the base (214) has two substantially parallel sides which are provided with wheels (218).

37. Filtration and maintenance unit according to claim 36, characterized in that the wheels (218) are arranged in two parallel lines, and each line comprises at least three wheels.

38. Filtration and maintenance group according to any one of claims 31 to 37, characterized in that the space between the edges of the base (214) and the inlet (222) of the assembly of circulation on the lower surface has a large extent and a low height.

39. Filtration and maintenance unit according to claim 38, characterized in that the edges of the lower surface of the base (214) are provided with a skirt (220).

40. Filtration and maintenance group according to claim 39, characterized in that the skirt (220) is formed by a member chosen from a flexible flap and bristles.