Patent Description:
It is known in the state of the art a filtering device for liquids. The known device comprises a first chamber, which has an inlet opening to receive liquid to be filtered. The device further comprises a second chamber, which has an outlet opening configured to discharge the filtered liquid. A filtering area is defined between the first and the second chamber.

In use, filtering material is introduced into the filtering area. Such material is typically an endless belt of paper, tissue or the like. In particular, the filtering material is unwound from a roller. The portion of such material inserted in the filtering area intercepts the liquid flow to be filtered, such to retain impurities.

In use, the filtering material tends to saturate with particulate, slowing down the liquid flow. When the flow falls beyond a preset limit, the belt portion being used is considered as saturated. The belt is thus further unwound so as to make the already saturated portion advance replacing it with a new portion of filtering material.

Disadvantageously, the efficiency of this type of filter depends on the fluid pressure upstream of the filtering area. In practice, such pressure is given by the pressure difference present between the first chamber and the discharge opening of the second chamber, therefore such parameter constitutes a limitation of the filter performance. It is not possible to increase the pressure by sucking the fluid with a pump, as a significant amount of air would be thereby sucked.

<CIT> discloses an endless media filtration system, with a pair of side walls, two containment discs rotatably mounted on a shaft between the side walls, and an endless loop filter media belt supported on an endless loop carrier belt. A media belt is attached to the carrier belt.

<CIT> discloses a filter device for separating a mixture of solid substance and a liquid, namely another example of an endless media filtration system.

Within this framework, the technical task underlying the present invention is to propose a filtering device for liquids that overcomes the above mentioned drawbacks of the prior art.

In particular, it is the object of the present invention to make available a filtering device for liquids capable of enabling a significant increase in efficiency.

The specified technical task and the specified purposes are substantially reached by a filtering device for liquids comprising the technical characteristics set forth in one or more enclosed claims.

In particular a filtering device for liquids according to the present invention comprises a first chamber having an inlet opening and configured to receive liquid to be filtered.

A second chamber has an outlet opening and is configured to discharge filtered liquid.

A filtering area is defined between the first and the second chamber. The filtering area is configured to receive a filtering belt.

The first chamber is defined at least partially by a pair of walls. Such walls are configured to rotate around an axis of rotation. The axis of rotation joins centres of the walls and is arranged perpendicular to both walls. Furthermore the walls each have a respective edge, which is configured to be pressed tightly against the filtering belt to drag it. The axis of rotation is oriented perpendicular to an advancement direction of the filtering belt.

The perimeter wall comprises a grid for the passage of the filtered liquid, the grid extending over a surface equal to or less than <NUM>% of the perimeter wall.

Such device overcomes the technical problem in that the sealing formed between the walls of the first chamber and the filtering belt allows to apply a suction pump in the second chamber, thus increasing the pressure exerted by the liquid on the filtering belt, other conditions being equal. Consequently, the device has a greater efficiency than already known filtering systems.

Advantageously, the second chamber is fluid-tightly closed, except for the outlet opening and the connection with the first chamber. Thereby, the effect of the action of the suction pump on the pressure difference is maximised at the filtering belt.

Further characteristics and advantages of the present invention will be more evident from the indicative, and therefore non-limiting, description of a preferred, though not exclusive, embodiment of a filtering device for liquids, as shown in the appended drawings wherein:.

With reference to the enclosed drawings, with reference number <NUM> is indicated a filtering device for liquids according to the present invention. Such device is of the belt type, namely it operates using a filtering material belt <NUM>. Such filtering belt <NUM> is unwound from a first roller <NUM>, inserted in a filtering area <NUM> where the filtering operation takes place, and, once saturated with material, rewound in a second roller <NUM>. In use, the filtering belt <NUM> is periodically advanced along an advancement direction "B".

Referring in particular to <FIG>, the device <NUM> comprises a first chamber <NUM>. Such first chamber <NUM> has an inlet opening <NUM>, which is configured to receive liquid to be filtered. The first chamber <NUM> is defined at least partially by a pair of walls <NUM>, which are configured to rotate around an axis of rotation "A".

In greater detail, the walls <NUM> are preferably circular. In the invention, the axis of rotation "A" joins the centres of the walls <NUM>, and it is arranged perpendicular to both walls <NUM>. Still in the invention, the axis of rotation "A" is oriented such to be perpendicular to the advancement direction "B" of the filtering belt <NUM>.

The walls <NUM> each have a respective edge 4a. Such edge is configured to be pressed tightly against the filtering belt <NUM>, so as to make it advance. It must be noted that each wall <NUM> is provided with a respective gasket <NUM> placed at the edge 4a. Such gaskets <NUM> are arranged to come into contact with the filtering belt <NUM>, so as to avoid outward leakages.

It must be noted that the device <NUM> comprises first movement means <NUM> that are active on the walls <NUM> such to rotate them around the already mentioned axis of rotation "A". Such first movement means may for example comprise a first motor <NUM>, preferably electric, connected to a shaft <NUM> arranged along the mentioned axis of rotation "A" and connected to the walls <NUM>.

Advantageously the first chamber <NUM> comprises one or more level sensors (not shown) such sensors are able to detect at least when the liquid reaches the minimum level and the maximum level inside the chamber <NUM>, and are preferably able to measure the exact level. Such data are used to assess if it is necessary to make the filtering belt <NUM> advance.

The device <NUM> is further provided with a second chamber <NUM>. Such second chamber <NUM> has an outlet opening <NUM>, which is arranged to discharge filtered liquid. The mentioned filtering area <NUM> is arranged between the first <NUM> and the second chamber <NUM>. In use, the liquid to be purified flows from the first <NUM> to the second chamber <NUM>, passing through the filtering area <NUM> such that the filtering belt <NUM> inserted therein may retain the dispersions within the fluid.

Referring in particular to <FIG>, the second chamber <NUM> is defined at least partially by an inner tank <NUM>. Such inner tank <NUM> is arranged under the first chamber <NUM> so that the liquid can flow by gravity. In addition, suction means (not shown) may be active downstream of the outlet opening <NUM>, so as to increase the pressure of the liquid at the filtering belt <NUM>.

The inner tank <NUM> is inserted inside an outer tank <NUM>, which has the function to collect further possible leakages and/or dragging of filtering and/or filtered liquid and to reintroduce them into the above described first chamber <NUM>. For this purpose, the outer tank <NUM> is provided with a drainage opening <NUM> which, in use, is put into fluid communication directly or indirectly with the first chamber <NUM>. The outer tank <NUM> further comprises one or more level sensors (not shown), which have the function of signalling a maximum level being reached.

According to the invention, the second chamber <NUM> has a perimeter wall <NUM>. Such perimeter wall <NUM> is arranged at the filtering area <NUM>, and circumferentially faces the walls <NUM> of the first chamber <NUM>. In other words, the perimeter wall <NUM> partially surrounds the walls <NUM> of the first chamber <NUM>.

It must be noted that the perimeter wall <NUM> is fluid-tightly connected to the inner tank <NUM>. In particular, the second chamber <NUM> has at least two fastening areas <NUM> wherein the perimeter wall <NUM> is fastened to the inner tank <NUM>. The second chamber <NUM> comprises a pair of additional gaskets (not shown) each placed at a respective fastening area <NUM>.

In the invention, the perimeter wall <NUM> comprises a grid <NUM> for the passage of the filtered liquid. The grid <NUM> extends over a surface equal to or less than <NUM>% of the perimeter wall <NUM>.

According to the present invention, the device <NUM> comprises a conveyor belt <NUM>, one portion of which is inserted into the filtering area <NUM>. Such conveyor belt <NUM> is preferably of the type made with polymeric links, such that it is permeable to the liquid to be filtered without hindering it. In particular, the conveyor belt <NUM> portion placed in the filtering area <NUM> is placed between the perimeter wall <NUM> of the second chamber <NUM> and the walls <NUM> of the first chamber <NUM>. In use, the conveyor belt <NUM> is placed in contact with the filtering belt <NUM> and has the function of pressing the filtering belt <NUM> against the edges 4a of the walls <NUM>, in particular against the gaskets <NUM>. It is worth noting that, at the edges placed in contact with the walls <NUM>, the conveyor belt <NUM> is impermeable. Such conveyor belt <NUM> if further arranged to be dragged by the rotation of the walls <NUM> of the first chamber <NUM>.

In greater detail, the conveyor belt <NUM> is closed in a loop. The portion of the conveyor belt <NUM> which is external to the filtering area <NUM> is in any case inserted in the outer tank <NUM>, such that possible leakages of the liquid soaking the conveyor belt <NUM> may be intercepted.

In further detail, the conveyor belt <NUM> is arranged on a pair of rollers 15a, 15b. In particular, a pair of first rollers 15a is arranged downward, at the inner tank <NUM>, such that the conveyor belt can pass below the inner tank <NUM>. A pair of second rollers 15b is also arranged at the sides of the inner tank <NUM>, in particular near the filtering area <NUM>, such that the conveyor belt <NUM> may pass though the filtering area <NUM> as previously described.

For moving the filtering belt <NUM>, at least one of the mentioned second rollers 15b is motorised, in particular connected by suitable transmission means <NUM> to the first movement means <NUM> driving the walls <NUM>, such to ease the synchronised movement of the walls <NUM> with the conveyor belt <NUM>. Such transmission means <NUM> may comprise a gear chain, a transmission belt or any type of similar known transmission.

According to an embodiment of the present invention, the device <NUM> is provided with an unwinder roller <NUM> placed near the filtering area <NUM>. Such unwinder roller <NUM> is arranged to unwind the filtering belt <NUM>, in particular from the first roller <NUM> which, in use, is mounted on the unwinder roller <NUM>. Preferably, the unwinder roller <NUM> is neutral.

The device <NUM> is further provided with a winder roller <NUM>, which has the function of winding the filtering belt <NUM> extracting it out of the filtering area <NUM>. While the device <NUM> is in function, the winding of the filtering belt <NUM> on the winder roller <NUM> defines the second previously mentioned roller <NUM>.

In order to operate the winder roller <NUM>, the device <NUM> comprises second movement means <NUM>. In the preferred embodiment of the invention, the second movement means <NUM> are of the pneumatic type. In particular, the second movement means <NUM> comprise an air turbine <NUM>. In further embodiments of the invention the second movement means <NUM> may be of any type.

Claim 1:
A filtering device (<NUM>) for liquids, comprising
- a first chamber (<NUM>) having an inlet opening (<NUM>) configured to receive liquid to be filtered, said first chamber (<NUM>) is defined at least in part by a pair of walls (<NUM>) configured to rotate around an axis of rotation (A), whereby the axis of rotation (A) joins centres of the walls (<NUM>) and is arranged perpendicular to both walls (<NUM>);
- a second chamber (<NUM>) having an outlet opening (<NUM>) configured to drain the filtered liquid, said second chamber (<NUM>) having a perimeter wall (<NUM>) placed at a filtering area (<NUM>) and circumferentially facing said walls (<NUM>) of said first chamber (<NUM>), the perimeter wall (<NUM>) comprising a grid (<NUM>) for the passage of the filtered liquid;
- the filtering area (<NUM>) is placed between the first (<NUM>) and the second chamber (<NUM>) and configured to receive a filtering belt (<NUM>), the axis of rotation (A) being oriented perpendicular to an advancement direction (B) of the filtering belt (<NUM>), said walls (<NUM>) each having a respective edge (4a) configured to be pressed tightly against said filtering belt (<NUM>) to drag said filtering belt (<NUM>);
- suction means active downstream of the outlet opening (<NUM>), the second chamber (<NUM>) being defined at least partially by an inner tank (<NUM>) arranged under the first chamber (<NUM>), the perimeter wall (<NUM>) being fluid-tightly connected to the inner tank (<NUM>)
characterised in that said grid (<NUM>) extends over a surface equal to or less than <NUM>% of the perimeter wall (<NUM>).