Patent Description:
Machines capable of converting the intrinsic energy of a fluid in motion (kinetic energy or enthalpy) into energy or mechanical work are known and used in the prior art for various purposes according to their size.

An example of these machines, also named dynamic fluid machines, are Tesla turbines (named after the inventor), which are widely and satisfactorily used in various sectors of mechanics, particularly in form of small and/or very small machines. Document <CIT> discloses a radial turbine.

The aforesaid machines, in particular the Tesla turbines according to the prior art, are based on the transformation of the energy contained in a fluid in motion, and therefore in a flow of fluid (e.g. air, and/or gas and/or steam), into mechanical energy and vice versa, wherein an adequate and optimal interaction between the fluid and a mechanical member capable of being rotated (the rotor) is necessary in order to obtain the desired transformation, and wherein the rotation of the rotor takes place by virtue of the viscosity of the fluid but is still dependent on the manner by which the fluid is guided against the rotor, usually by means of a fixed component part of the turbine called stator.

In practice, the degree of transformation of the fluid energy into mechanical energy, and therefore the efficiency of the turbine or machine, depends on the manner by which the flow is guided against the rotor, wherein one of the determining factors of turbine efficiency is represented by the conformation of the stator, usually ringshaped, wherein the fluid in motion outside the stator is guided by the stator itself against the rotor, the stator being equipped, for the purpose, with a number of through holes or nozzles which connect the space in which the rotor is housed with the space outside the stator.

Although satisfactory from many points of view, e.g. such as reliability, the known machines are not exempt from problems and/or disadvantages that the present invention intends to overcome or at least to reduce or minimize.

A first drawback relates to the fact that in most known machines, and especially in those of small size, the stator, especially if obtained by mechanical machining from a billet (by means of a drill or the like), has a limited number of nozzles, wherein the minimum size of the nozzles and their mutual distance are, on the contrary, too high, so that zones in which there is flow (the nozzles or holes) and zones (full) in which there is no flow are inevitably present along the extension of the rotor/stator boundary zone; however, this alternation causes vortices and strong frictions on the walls because the radial speed component is not null and the speed gradient itself can reach very high values, also in this case with large losses of performance. Another serious problem affecting the known machines or turbines is their (excessive) lack of flexibility; indeed, it is apparent that a stator, especially if obtained by machining an original billet, is a unique piece which cannot be modified and which can be implemented in one only machine or turbine because it cannot be used on turbines with specifications differing from those of the machine for which it was originally designed and built.

Furthermore, a further problem found in stators according to the prior art is related to the inevitable tolerances, wherein it is practically impossible to obtain perfectly identical stators, especially by machining an original billet, i.e. with holes or nozzles all with the same diameter and at the desired mutual distances, wherein the unevenness in the dimensions and/or mutual distances results in the equally inevitable presence of different flows (in terms of flow rate, speed, direction etc.) in the boundary zone between stator and rotor, and therefore still with the aforesaid losses of efficiency.

Finally, a further problem found in the prior art is represented by the manufacturing times of the stator, especially but not exclusively if it is made by machining an original billet, said times being far too high with consequent obvious repercussion on production costs, often impractical for applications of wider use.

Examples of machines according to the prior art for generating energy by exploiting the flow of a fluid are known from <CIT> and <CIT>.

It is thus the object of the present invention to overcome or at least minimize the drawbacks affecting the solutions according to the prior art, in particular dynamic fluid machines or turbines according to the prior art for converting the energy of a fluid in motion into mechanical energy, in particular in the rotation of a rotor.

In particular, it is an objective or object of the present invention that of providing a machine of the aforesaid type in which the fluid flow is distributed virtually seamlessly throughout the stator-rotor boundary zone.

It is a further object of the present invention also to distribute the points of introduction of the motive fluid along the entire boundary zone, so as to minimize the sliding thereof on the walls, thereby limiting losses by friction on parts which do not generate work and/or to maximize the speed components which are not tangent to the surfaces.

It is a further purpose of the present invention to provide a stator which can be manufactured in a simple and immediate manner (in particular not necessarily by machining an original billet) and at low cost, and is also characterized by high and improved reproducibility in terms of both the overall size of the stator itself, and in terms of size and/or distance and/or reciprocal shape of the holes or nozzles.

Furthermore, the stator according to the present invention shall adapted to be modified according to the needs and/or circumstances.

The present invention is based on the various general considerations briefly summarized below.

The desired uniformity of the fluid flow can be obtained by means of a substantially "porous" stator, i.e. in which the nozzles are very high in number (in the order of even several hundred) and very small in size.

A substantially "porous" stator can be obtained at a reasonable cost using alternative technologies to both machining from billet and 3D printing (which do not guarantee the desired accuracy and require very long printing times).

A substantially "porous" stator with the desired characteristics can be obtained by means of "additive" technology according to which previously processed, substantially identical elements are added to each other.

The substantially identical elements to be "added", in practice to be superimposed, can be processed beforehand using low-cost technologies, such as metal chemical photoengraving (photoetching), which ensure very small size machining with maximum precision.

In view of the drawbacks found in the solutions according to the prior art, of the objects summarized above, and of the conditions illustrated hereto, a machine according to claim <NUM> is suggested according to the present invention.

According to an embodiment, said at least one lamellar element which defines said non-contact areas with the lamellar element adjacent thereto, defines a substantially flat main surface, from which a plurality of protrusions extends.

According to an embodiment, the thickness of said protrusions is substantially equal to the thickness of said at least one lamellar element at said non-contact areas subtended from said main surface.

According to an embodiment, the thickness of said protrusions is from <NUM> to <NUM> millimeters, preferably from <NUM> to <NUM> millimeters, even more preferably from <NUM> to <NUM> millimeters.

According to an embodiment, said protrusions each have an elongated plan shape with a longitudinal development along a directrix perpendicular to the longitudinal symmetry axis of said first cylindrical fixed component part of a stator.

According to an embodiment, each of said protrusions comprises a first end portion arranged at said first inner surface.

According to an embodiment, each of said protrusions comprises a second end portion arranged at a predetermined distance from said second outer surface. According to an embodiment, said second end portion of each of said protrusions is hook-shaped and defines an end tip facing said second outer surface.

According to an embodiment, the longitudinal extension directrix of each of said protrusions is tangential to said first inner surface and intersects said second outer surface.

According to an embodiment, the two protrusions of each pair of adjacent protrusions partially overlap each other according to a radial direction perpendicular to the longitudinal symmetry axis of said first fixed component part of a stator. According to an embodiment, said protrusions are obtained by chemically photoengraving a lamellar element of substantially uniform thickness.

According to an embodiment, each of said lamellar elements comprises at least two through-holes, wherein said lamellar elements are mutually fixed by fixing means, which extend through said at least two through-holes of said lamellar elements. According to an embodiment, said lamellar elements are fixed to one another by one of the following methods:.

According to an embodiment, said second component part or rotor comprises a main body accommodated in said inner space and consisting of a plurality of overlapping discoid elements, wherein the discoid elements of each pair of adjacent discoid elements are placed at a mutual predetermined distance.

According to an embodiment, said second component part or rotor comprises a main body accommodated in said inner space and consisting of a plurality of radial blades.

According to an embodiment, the outer edges in radial direction of said blades lie on a common frustoconical surface.

Further possible embodiments of the present invention are defined in the claims.

In the following, the present invention will be explained by means of the following detailed description of the embodiments depicted in the drawings. However, the present invention is not limited to the embodiments described in the following and depicted in the drawings; on the contrary, all the variants of the embodiments described below and depicted in the drawings which will be apparent to a person skilled in the art have to be regarded as falling within the scope of the invention.

The present invention is particularly advantageously when implemented in the field of machines for converting the energy of a fluid into mechanical energy, this being the reason why, in the following, the present invention will be clarified with (possible) reference to its application to the case of the aforesaid machines, in particular to Tesla type turbines, in all cases the possible applications of the present invention not being limited to the aforesaid machines nor to Tesla type turbines.

The machine <NUM> depicted in <FIG> and <FIG> comprises a fixed outer casing or container <NUM>, in which a first fixed component or stator <NUM> and a second rotatable component or rotor <NUM> are housed.

The stator <NUM> has a substantially cylindrical annular shape and therefore either defines or comprises a substantially cylindrical inner surface of predetermined diameter <NUM>, and an essentially cylindrical outer surface of predetermined diameter <NUM>, the diameter of the surface <NUM> being obviously greater than that of the inner surface <NUM>, wherein the difference between the radius of the surface <NUM> and that of the surface <NUM> defines the thickness of the stator <NUM> along the direction R perpendicular to the longitudinal symmetry axis X of the stator <NUM>. The rotor <NUM>, as depicted, is housed in the inner space <NUM> defined and/or confined by the inner surface <NUM> of the stator <NUM>, and is adapted to be rotated with respect to a rotation axis coinciding with the axis X, wherein the rotor <NUM> comprises a plurality of overlapping discoid (disc shaped) elements <NUM> splined onto a rotation shaft A, the discoid elements <NUM> being spaced mutually along the shaft A, wherein each pair of adjacent discoid elements <NUM> defines a cavity. The diameter of the rotor <NUM> is smaller than that of the inner surface <NUM> of the stator <NUM>, wherein there is a gap or boundary zone between stator <NUM> and rotor <NUM>. The operation of the machine <NUM> is substantially similar to that of the dynamic fluid machines according to the prior art, wherein, by means of the stator <NUM>, a fluid in motion in the space <NUM> outside the stator <NUM> (between stator <NUM> and outer container <NUM>), is conveyed through the stator <NUM> (through a plurality of passages <NUM>, each of which puts the outer surface <NUM> and the inner surface <NUM> into communication) into the space <NUM> and thus towards the rotor <NUM>, wherein the viscosity of the fluid translates into an interaction between the fluid and the rotor <NUM>, and thus into the rotation of the rotor <NUM>.

As mentioned above, the efficiency of the machines of the type depicted in <FIG> and <FIG>, and therefore the degree of transformation of the energy of the fluid into mechanical energy or work, depend on the manner by which the fluid interacts with the rotor <NUM>, and therefore on the manner by which the fluid is conveyed by means of the stator <NUM> towards rotor <NUM>.

Again, as anticipated, according to the present invention, the stator <NUM> has innovative features which allow optimizing the interaction mode between fluid and rotor <NUM>; an example of said innovative characteristics or features is described hereinafter with reference to <FIG>, wherein characteristics or features and/or component parts of the present invention already described above with reference to other figures are identified by the same reference numerals in figures from <NUM> to <NUM>. As depicted in figures from <NUM> to <NUM>, the stator <NUM> consists of a plurality of superimposed lamellar elements <NUM>, each lamellar element <NUM> having a circular crown shape with an inner circumference of diameter corresponding to that of the surface <NUM> and an outer circumference of diameter corresponding to that of the surface <NUM>.

Furthermore, and again as depicted, each lamellar element <NUM> comprises a plurality of protrusions <NUM> arranged regularly in succession along the circular development of the element <NUM>, wherein each protrusion <NUM> extends from the main surface <NUM> along a direction parallel to the axis X, each protrusion <NUM> having in particular a predefined thickness sp, substantially corresponding to the thickness sl of the element <NUM> in correspondence of those parts of element <NUM> not subtended by (not overlapping with) protrusions <NUM>. Therefore, in the case, inter alia, in which the elements with protrusions <NUM> are obtained by photochemical engraving (etching) and/or chemical shearing from a starting plate of substantially uniform thickness, the thickness of the protrusions <NUM> will be substantially equal to half the thickness of the original plate. Furthermore, if the elements and the protrusions <NUM> are obtained by chemical or photochemical engraving of a precut starting lamellar element with a substantially uniform thickness, the thickness of the protrusions <NUM> will be substantially proportional to the time and action of the chemical etching. Therefore, it can be appreciated that by superimposing the lamellar elements <NUM> to form the stator <NUM>, as depicted in <FIG>, two adjacent lamellar elements will be in mutual contact only at the protrusions <NUM>, wherein N-<NUM> passages <NUM> (given N the number of protrusions <NUM>) will be defined and identifiable between two adjacent lamellar elements <NUM>, wherein each passage <NUM> extends from the inner circumference towards the outer perimeter of the lamellar element <NUM>, and wherein with the lamellar elements <NUM> superimposed to form the stator <NUM>, as depicted in <FIG>, each passage extends between the inner surface <NUM> and outer surface <NUM> and thus puts the outer space <NUM> and the inner space <NUM> into communication.

Again, as depicted (<FIG> and <FIG>), the protrusions <NUM> are shaped and mutually arranged so that the flow of fluid through a channel <NUM> defined between two adjacent protrusions <NUM> is substantially tangent to the cylindrical outer surface of the rotor <NUM>.

In this respect, it is worth noting first of all that each protrusion <NUM> has a longitudinal extension in a plane perpendicular to the axis X along a directrix D tangent to the inner circumference of the corresponding lamellar element <NUM>, wherein the directrix D on the contrary intersects the outer perimeter of the lamellar element <NUM> (<FIG>).

Furthermore (<FIG>), each protrusion <NUM> comprises a first end portion <NUM> placed at the inner circumference of the lamellar element <NUM>, and a second end portion <NUM> opposite to the first end portion <NUM> and placed at a predefined distance from the outer perimeter of the lamellar element <NUM>. In particular, while the first portion <NUM> substantially extends along the main directrix D, the second end portion <NUM> deviates from said main directrix D and is shaped as a hook with an end point <NUM> facing the outer perimeter of the lamellar element <NUM>. Therefore, each passage <NUM> comprises a larger V-shaped inlet towards the outer perimeter, and a narrower outlet towards the inner circumference of the element <NUM>.

Finally, as depicted, two adjacent protrusions <NUM> are partially superimposed along a radial direction R, the second end portion <NUM> of one of the two protrusions <NUM> being superimposed on (overlapped with) the first end portion <NUM> of the second protrusion <NUM>.

The mutual conformation and arrangement of the protrusions <NUM>, as anticipated, allows generating, inside the stator <NUM>, a plurality of micro-flows of fluid, one for each passage <NUM>, each substantially tangent to the inner surface <NUM> of the stator <NUM>, wherein each of said micro-flows intercepts the rotor <NUM> according to a direction substantially tangent to the outer surface of the rotor <NUM> (<FIG>). Hereafter, a further embodiment of a stator <NUM>, which can be implemented in a machine according to the present invention, will be described with reference to figures from 7a to 7c.

As depicted, in the case of the embodiment in figures from 7a to 7c, the stator <NUM> again comprises a plurality of lamellar elements <NUM> superimposed according to the methods described above, wherein, however, in this case, each lamellar element <NUM> comprises a plurality of openings A arranged in sequence with radial regularity along the circular extension of the lamellar element <NUM>, and wherein each opening A extends transversally to the main surface <NUM> for the entire thickness sl of the element <NUM>, and thus so as to put the surface <NUM> in communication with the corresponding opposite surface.

Therefore, with the lamellar elements <NUM> superimposed as depicted in <FIG> to define the stator <NUM>, the openings A (in mutual correspondence) define a corresponding plurality of AC channels which each extend parallel to the axis X, and which can be used as input channels for the introduction of the fluid into the inner space <NUM> through the inner surface <NUM> (again cylindrical) and the outer surface <NUM> (discontinuous, in this case).

The stator <NUM> according to this embodiment allows avoiding the use of the outer casing <NUM>, which is necessary, on the contrary, in the case of the embodiments described above, for defining the channels or input passages <NUM>.

It has thus been demonstrated by means of the above detailed description of the embodiments of the present invention as depicted in the drawings that the present invention achieves the predetermined objects by overcoming the drawbacks found in the prior art.

In particular, the present invention allows making a substantially "porous" stator, i.e. comprising a plurality of micro-passages <NUM> at reasonable costs, using technologies alternative to both machining from billet and 3D printing (which do not ensure the desired precision and require very long printing times), particularly according to additive technology methods, which envisages the addition of substantially identical elements previously processed, for example, but not exclusively by photochemical engraving and/or etching.

Furthermore, by means of the present invention, a machine is made available in which the flow of fluid is distributed practically seamlessly along the entire stator-rotor boundary zone, i.e. in which the motor fluid points of injection or input are distributed along the entire boundary zone, so as to minimize the sliding of the fluid on the walls, and thus limiting friction losses on parts which do not generate work and/or which maximize the speed components which are not tangent to the surfaces.

Furthermore, the stator according to the present invention can be made in simple and immediate manner (in particular not necessarily by machining an original billet) and at low cost, and is also characterized by high and improved reproducibility in terms of both the overall size of the stator itself, and in terms of size and/or distance and/or reciprocal shape of holes or nozzles.

Finally, the stator according to the present invention will be modifiable according to needs and/or circumstances, wherein the substantially identical elements to be "added", in practice to be superimposed, can be processed beforehand using low-cost technologies, such as metal chemical photoengraving, which ensure machining of very small dimensions with maximum precision.

Although the present invention has been explained above by means of a detailed description of the embodiments depicted in the drawings the present invention is not limited to the embodiments described above and depicted in the drawings. On the contrary, all the modifications and/or variants of the embodiments described above and depicted in the drawings which will appear obvious and immediate to a person skilled in the art have to be regarded as falling within the scope of the present invention.

For example, one or more of the following parameters may be varied according to needs and/or circumstances:.

Furthermore, possible embodiments of the present invention will be possible in which different lamellar elements <NUM> may have protrusions <NUM> differing in number and/or shape and/or thickness and/or with different locations to define respectively different passages <NUM> in the stator <NUM> itself.

Furthermore, according to the present invention, the discoid (disc shaped) elements <NUM> of the rotor <NUM> may be fixed to one another and/or splined to shaft A in different manners, e.g. by means of pins which extend through through-holes made in each element <NUM>.

Finally, different rotors may be used as an alternative to the one in <FIG> and <FIG>, e.g. a rotor of the type shown in <FIG> and <FIG> and therefore comprising radial blades <NUM>, each parallel to a plane containing the axis X and each delimited by an outer edge lying on a truncated cone surface.

Claim 1:
A machine (<NUM>) for generating energy by exploiting the flow of a fluid, said machine comprising a first cylindrical static component part being a stator (<NUM>) which defines a first cylindrical inner surface (<NUM>) and a second outer surface (<NUM>), said machine (<NUM>) further comprising:
a second component part being a rotor (<NUM>) adapted to be rotated and accommodated in the inner space (<NUM>) confined by said first inner surface (<NUM>),
said stator (<NUM>) being shaped so as to allow the introduction of a fluid into the inner space (<NUM>) confined by said first cylindrical inner surface (<NUM>) through said second outer surface (<NUM>) and first cylindrical inner surface (<NUM>),
wherein the interaction between said flow of fluid introduced into said inner space (<NUM>) and said rotor (<NUM>) results in said rotor (<NUM>) being rotated;
characterized in that
said stator (<NUM>) comprises a plurality of overlapping lamellar elements (<NUM>),
wherein each lamellar element (<NUM>) having a circular crown shape with an inner circumference of diameter corresponding to that of the first cylindrical inner surface (<NUM>) and an outer circumference of diameter corresponding to that of the second outer surface (<NUM>),
wherein at least one of said lamellar elements (<NUM>) is shaped so as to define non-contact areas with a lamellar element (<NUM>) adjacent thereto, and therefore so as to define, with the lamellar element (<NUM>) adjacent thereto, a plurality of passages (<NUM>) for said fluid,
wherein each of said passages (<NUM>) puts into communication said inner space (<NUM>) with the space (<NUM>) outside said second outer surface (<NUM>).