Technical field

The present invention refers to the technical field relative to the filtering of a fluid, in particular of oils and liquids in general, for the removal of particles of impurities.

In particular, the invention refers to an innovative filtering device of the electrostatic type.

Background art

Filters for fluids have long been known, in particular mechanical filters.

These filters are constituted by a thick mesh network of a pre-determined width in such a way that the particles of impurities, above a certain diameter, remain trapped in the networks, while the pure part of the fluid continues to circulate.

A technical problem linked to this type of mechanical filter, well known in the state of the art, is that these filters are not capable of blocking particularly small particles, for example below the 3-5 microns of diameter. In order to allow a block of particles of such dimensions, it would be necessary to realize networks of such a thickness that the possibility that they clog, causing an occlusion of the filter itself and a consequent pressure fall, is very high. The thicker the networks of the filters are, the more frequent the substitution of them is.

In order to optimize the filtering process, therefore, electrostatic filters have been though of time ago, such as the one described in patent US4594138 in the name of Thompson. In this case a cylindrical element is included, forming a circulation conduit and having an inlet for the fluid to be filtered and an outlet for the filtered fluid. Inside the cylinder holed septums are included, in the shape of discs and that constitute electrodes, at different heights along all the height of the cylinder. The electrodes are loaded alternatively in the positive and negative manner through a connection of each one of them to a positive or negative pole of a potential source. The electrodes are therefore loaded in sequence, one positively and the subsequent one negatively (or vice versa) .

The space comprised between a septum and the subsequent one is then filled with a filtering material.

In use, when the fluid enters inside the cylinder, the particles go through the holes of the first disc of electrode, for example connected to the positive pole. In this manner, a good part of the particles will be loaded positively, while other particles will remain neutral. The passage to the subsequent disc, loaded negatively, will cause that a good part of the neutral particles will be loaded negatively and will combine with the positive ones, thus creating an impurity of a greater diameter. The progressive passage therefore creates an increase of diameter of the impurities, as the neutral particles load positively or negatively and combine among them. The progressive passages therefore cause a progressive block of the particles in the filters arranged into the cylindrical body.

It is anyway clear that this solution is not particularly functional for the following reasons.

The same electrodes, in the shape of a disc similar to a filter, are subject to a potential obstruction that limits their functionality and determines their rather frequent substitution.

Moreover, the filters will be progressively substituted, also causing a complex disassembly of the entire cylinder.

It is also essential that there is a mixing effect, and therefore a vorticose motion, that favour the conjunction among the particles of impurities of opposite load. It is clear that the system just described does not favour at all a good mixing of the particles, therefore the possibility that they mix, reciprocally attracting themselves, is not high. As a result of this, even if a different number of particles has been loaded with a positive or negative load, the same will not combine with particles of opposite load because they are distant from each other and therefore they will elude the filtering system in se.

Disclosure of invention

It is therefore the aim of the present invention to provide an electrostatic filtering device that solves at least in part said technical inconveniences.

In particular, it is the aim of the present invention to provide a filtering device for a fluid, such as oils, dielectric fluids and similar, that allows an efficient filtering of particularly small particles, also well below the 3 microns.

These and other aims are therefore obtained with the present filtering device for a fluid in accordance with claim 1.

The filtering device in accordance with the invention comprises:

- A fluid circulation path (Gl, G2 ) and;

- Means (01, 02, 0) to electrically load at least a part of said path (Gl, G2) and comprising a positive load device (01) to load positively the path, and a negative load device (02) to load negatively the path.

In accordance with the invention, the path (Gl, G2) is such as to form a first (Gl) and a second path (G2) distinct between them. The two paths (Gl, G2) are such that one of them results connected to the positive load device (01), while the other one results connected to the negative load device (02). . In this manner, the fluid in entry in the positive load path will be loaded positively, while the other one will be loaded negatively.

Specifically, according to the voltage used, the impurities present in it will be polarized or will be ionized according to the intensity of the potential used, therefore re-distributing or losing their loads.

A mixing chamber (L) is arranged in such a way that the fluid, once polarized or ionized and in exit from the two conduits (Gl, G2 ) , mixes, causing an electrostatic aggregation of the impurities, which increase of diameter. It is therefore clear that all the aims pre-established by the invention have been reached.

In particular, it is clear that the fluid, which now circulates in an independent manner inside the two paths, loads very uniformly. The paths for the electric loading lack filters, while, only in exit from the path inside the mixer, a turbulent motion effect is created that favours the conjunction between the particles loaded positively and those loaded negatively. In this manner, also particles well below the 3 microns aggregate easily. It is therefore clear that such a solution, unlike the background art, allows a very efficient electrostatic aggregation of impurities.

In particular, structurally the system is simple since the actually filtering part can be placed downstream of the mixer and constituted by a simple mechanical filter (P) which can now easily and quickly be substituted in a quick manner when it results necessary.

It is also possible to operate easily, in accordance with said solution, a speed control of the circulating fluid in such a way as to optimize its electrostatic load, as it is possible also to operate a control on the mixing in the mixing chamber that optimizes the contact between the positive particles of impurities with the negatively loaded ones.

The present technology therefore allows the filtering of impurities below the 3 microns, easily arriving also to dimensions of the order of the tenth of micron, obviously after the efficient aggregation of said particles in bigger agglomerates.

Further advantages are deduced from the dependent claims .

Brief description of drawings

Further characteristics and advantages of the present invention will result clearer with the description that follows of some embodiments, made to illustrate but not to limit, with reference to the annexed drawings, wherein :

- Figure 1 shows, in accordance with a block scheme, a device in accordance with the invention;

- Figure 2 shows, in an axonometric view, a possible solution of realization of the ionizing assembly (E) , which comprises the two separated paths (Gl) and (G2) and incorporates also the mixer (L) ;

- Figure 3 shows the view in plant of the assembly (E) with the indication of the directions of inlet and outlet of the fluid;

- Figure 4 shows, in an axonometric view, an electrode which, as described below, has preferably an helicoidal shape in order to maximize the production of pseudo-ions;

- Figure 5 shows a section of the electrode placed inside a conduit Gl or G2;

Description of some preferred embodiments

Figure 1 shows, in a block diagram, the following device in accordance with the invention.

In particular, a pump (B) is included, which draws from a can (2) the fluid to be purified.

The fluid, through the pump (B) , is pushed in a first stadium constituted by a mechanical pre-filter (Dl), for example a network filter of a pre-determined width. The pre-filter therefore operates a filtering of the macro particles of impurities, thus sending them to the subsequent purification, placed downstream of said pre- filter, a fluid at least partially cleaned.

Right after the pre-filter, a part of fluid is sent to a first polarizing conduit (Gl), while the other part is sent to a second polarizing conduit (G2) . The two conduits are separated between them and therefore constitute two distinct paths (Gl, G2) for the fluid. As shown in the block diagram of figure 1, the fluid, once exited from the two conduits (Gl, G2), mixed into a mixer (L) that generates a vorticose motion which, as better described in detail below, favours the aggregation among the particles.

The two conduits (Gl, G2) are respectively connected one to a positive control (01) and one to a negative control (02), both connected naturally to a potential generator (0) . In substance, the positive control loads positively the conduit (Gl) , polarizing positively the fluid freely circulating inside it. The negative control (02) loads negatively the conduit (G2), polarizing negatively the part of fluid circulating in it.

In said configuration of the invention, therefore, the difference of potential generated by the generator is controlled in such a way as to polarize the fluid and obtain "pseudo-ions". In that case, a range of functioning that varies from the 5000V and the 7000V is therefore used.

As it is well known, the pseudo-ions are generated through an electrostatic excitation at controlled energy and limited power not sufficient for the generation of ions. In this case, the energy is not sufficient to cause the liberation of electrons but it rather simply causes a re-distribution of it, creating temporaneously concentrations of positive and negative load in the molecule itself. In a pseudo-ion, therefore, the total load inside a molecule remains always unvaried and the electrons are only placed in a different manner, creating a dipole.

These molecules, thus treated, are called pseudo-ions because, though not being true and real ions, they have anyway a very similar behaviour to the behaviour of the ions from the point of view of the electrostatic interaction with the other molecules.

Their behaviour from the electric point of view is similar to that of the ions since they can attract or reject themselves (on the basis of the orientation they have in the space and to the load distribution) . If all the molecules had the same orientation in the space, the probabilities of aggregation would diminish. For this reason, some energy outputs have been placed in perpendicular position with respect to the motion of the fluid with the aim of generating a Brownian motion of the molecules to facilitate the collision and the aggregation.

The great technical advantage of this production technology of pseudo-ions is therefore that of avoiding repercussions on the physical properties of the molecule itself and on the fluid that is being purified. In particular, not being freed electrons, the risk of a pollution of the fluid to be purified with an excess of free electrons and therefore the problem of a generation of eventual electrical discharges is avoided. Moreover, the generation of ions would require more energy since it is more the energy requested to cause the escape of an electron, rather than its re-positioning.

In a second configuration of the invention, nevertheless, nothing would impede to introduce such a difference of potential as to cause a ionization of the molecule. In this case, the orientative values of potential are superior to the 7.500 V.

Figure 2 shows structurally, in a possible constructive solution, the assembly of polarization E that comprises both the two distinct paths Gl and G2 and the mixer. The assembly is structurally an external cylinder E furnished with an inlet hole (IN) for the fluid to be purified and an outlet hole (OUT) for the filtered fluid.

This configuration has the advantage of being particularly compact.

The cylinder contains coaxially inside it the other structural elements described below.

In particular, the two cylindrical-shaped paths (Gl, G2) are represented, placed one beside the other and arranged inside a second cylinder L which forms the mixing chamber and contained, in turn, inside the main cylinder E. The two cylinders Gl and G2 are connected to the electrical feeding 01 and 02.

Figure 2, as also figure 3, clearly show the path of the fluid.

In particular, the fluid in entry from the inlet (IN) is separated in such a way that a part of it circulated in the conduit Gl and a part in the conduit G2 and of which one is loaded positively and the other one negatively (or vice versa) . The fluid, subject to said electrical potential, is polarized, generating pseudo- ions. The polarized fluid mixes both in the cylindrical crown (1/ ) and in the more external one (L' ' ) until reaching the exit through the hole (OUT) .

The two distinct flows (one positive and the other one negative) therefore mix, once ionized or polarized, inside the mixer (L) , formed in this case by the crown (L' ) and (L' ' ) . Being positively loaded molecules mixed with negatively loaded ones, these inevitably aggregate, forming impurities of greater dimensions. Once aggregated, the molecules form an aggregate of superior dimensions and the electrons will re-distribute inside it (the dipole state comes to its end) .

The heavier particles, aggregated during the mixing, fall to the bottom of the cylinder E, while the other ones will be blocked by the mechanical filter P, placeable downstream outside the cylinder E.

As shown schematically in figure 1, it would be possible to foresee a close-circuit circulation repeated more times in order to improve the filtering qualities. In particular, in exit from the filter P, it is possible to address in feed-back again the filtered fluid to the can 2 and from here re-emit it inside the assembly E through the pump B for the necessary number of times (two or more) .

At the end of the filtering the cleaned liquid can be sent through the pump 3 to an external station 1.

Naturally, it is clear that the solution of figure 2 can be modified by arranging the mixer L in sequence with respect to the two paths Gl and G2 and not realizing a single cylindrical-shaped assembly with chambers coaxial among them.

The present invention, without any limitation, is applicable to all types of fluids, such as hydraulic oils, lubricating oils, cooling fluids, diesel combustibles, engine oils, transmission fluids, vegetal oils and therefore liquids containing impurities.

Figure 4 shows the preferred shape of the electrode, which is helicoidal for better favouring and render more uniform the polarization of the fluid circulating in the conduit. The section of figure 5 shows the electrode in the conduit (Gl, G2) .

In use, when the system is fed, this generated two magnetic fields, one for each electrode. These fields create dipoles in all the undesired particles that pass in the operative range of the electrode. Each electrode has such a shape as to maximize the probability that a single particle enters in the operative zone. In a path there will be a spatial arrangement of the particles of the positive or negative type, while in the other path there will be an opposite spatial arrangement (due to the opposite electrical field) . This alignment creates a dipole (pseudo-ion) without causing the loss or the acquisition of electrons by the molecule itself or, alternatively, could be furnished energy for the jolt.

A measuring system of the dielectric properties of the fluid (not represented in figure) allows a control and an eventual variation of the tension on the electrodes, modulating the resulting electrical field in such a way as to minimize the production of ions and increase the production of pseudo-ions in case their concentration is modifying sensibly the dielectric properties of the fluid.