Kinetic energy accumulator

Technical Field

The present invention relates to a kinetic energy accumulator.

State of the Art

There are known accumulators that comprise a casing in which a disc- shaped flywheel is located, the flywheel being equipped with a shaft supported at its ends by superconducting magnetic means, which keep it suspended inside the casing.

To obtain significant energy exchanges, the weight of the flywheel and support shaft is equal to several hundred kilograms or even tons.

Electrical windings arranged on the surface of the flywheel and casing make it possible to set the flywheel into rotation, thus acting as an electric motor. When needed, the accumulated kinetic energy can be reconverted into electrical energy, once again by means of the interaction of these electrical windings. This makes it possible to accumulate energy at times when the power offtake from the grid is low (for example at night) to then restore it at peak times (or in any case, to stabilize and make the offtake of electrical power uniform.

One drawback of this design solution relates to the fact that the superconductor needs to be kept at very low operating temperatures and it therefore requires significant energy consumption (which is thus eliminated from the possibility of accumulation on the part of the flywheel). Moreover, the use of superconductors would appear to be necessary to sustain a cumbersome flywheel that also has a significant mass (which, in turn, is necessary to be able to realize significant energy exchanges).

Aim of the invention

In this context, the aim of the present invention is to make available an energy accumulator that is capable of optimizing the components, enabling the reduction of production costs and the increase of energy efficiency. The defined technical task and the specified aims are substantially achieved by a kinetic energy accumulator comprising the technical characteristics set forth in one or more of the appended claims.

Brief description of the drawings

Further characteristics and advantages of the present invention will become more apparent from the approximate and thus non-limiting description of a preferred, but not exclusive, embodiment of a kinetic energy accumulator as illustrated in the accompanying drawings, of which: -Figure 1 is a schematic view of an accumulator according to the present invention;

-Figure 2 is a schematic view of a component of an accumulator according to the present invention.

Detailed description of preferred embodiments of the invention

A kinetic energy accumulator is indicated by reference number 1 in the accompanying figures.

This accumulator 1 is capable of accumulating kinetic energy to then restore this kinetic energy, when needed, typically in the form of electrical energy.

The accumulator 1 comprises:

-a rotating rotor 2;

-a casing 3 for containing the rotor 2;

- first means 4 that magnetically interact with each other and that are located on said casing 3 and on said rotor 2 so as to keep the rotor 2 suspended inside the casing 3. This takes place by means of a magnetic force which overall opposes the force of gravity. Moreover, the first means 4 make it possible to keep or in any case, contribute to keeping the rotor 2 distanced from the casing 3 during normal operation.

The first means 4 comprise a first component located on the rotor 2 and a second component located on the casing 3; they are facing each other and interact with each other by means of a magnetic force.

Advantageously, the first means 4 are permanent magnets, but they could possibly also be electromagnets or a combination of permanent magnets and electromagnets. By way of example, in a lower part of the rotor 2, the first means 4 exert a repulsive force which thus opposes the force of gravity, while in an upper area of the rotor 2, the first means 4 exert a repulsive force (jointly with the force of gravity so as to keep the rotor 2 distanced from the casing 3).

The accumulator 1 further comprises second means 5 that interact magnetically and are located on said casing 3 and on said rotor 2, and the interaction of which, in a first operating mode, makes the rotor 2 rotate.ln particular, in this first operating mode, the second means 5 comprise electromagnets located on said casing 3 and permanent magnets located on the rotor 2. In this manner, the electromagnets located on the casing 3 generate a rotating magnetic field that interacts with the permanent magnets located on the rotor 2 without physical contact between the casing 3 and the rotor 2.

Conveniently, during operation, the rotor 2 and casing 3 are not in contact with each other and this makes it possible to minimize friction, thereby optimizing efficiency.

The rotor 2 conveniently comprises at least one lower convex spherical cap 20. The first means 4, which interact magnetically, are at least partly arranged on said spherical cap 20 and at least partly arranged on a portion of the casing 3, which faces this spherical cap 20.

The rotor 2 comprises an external surface 24. This surface delimits the entire rotor 2 externally. Let there be defined a first and a second imaginary sphere 61 , 62, the first sphere 61 being the sphere of maximum radius which lies entirely within the external surface 24 of the rotor 2, the second sphere 62 being the sphere of minimum diameter which lies entirely outside of the rotor 2. Conveniently, the first and the second sphere 61 , 62 are concentric. The difference between the radius of the second sphere 62 and the radius of the first sphere 61 is less than 0% of the radius of the second sphere 62 (preferably, this difference is less than 3% of the radius of the second sphere 62, and even more preferably it is less than 15 centimetres). This makes it possible to take into account possible tolerances on the external surface 24, given that in the preferred solution, the rotor 2 is substantially spheroidal (see Figure 2).

The use of a spherical or substantially spherical rotor 2 (within the dimensional tolerances defined hereinabove) makes it possible to optimize the distribution of the first means 4 on the rotor 2, thereby enabling their distribution over an ample surface area so as to avoid the use of localized superconductors that require very low operating temperatures (thereby reducing the efficiency of the accumulator). The first means 4 can thus be distributed along the rotor 2 (over an ample surface area given the spherical shape of the rotor 2) and operate at ambient temperature, for example at least at a temperature ranging between 10°C and 40°C. The rotor 2 can therefore be kept at ambient temperature.

Conveniently, the first means 4 extend in a crown arrangement (preferably both along the rotor 2 and along the casing 3).A line connecting in succession the first means 4 arranged along the rotor 2 or along the casing 3 is undulating. This solution facilitates realignment of the axis of rotation of the rotor 2 along the predetermined direction (perpendicular to the direction of the plane of the crown).

Moreover, the rotor 2 of a spherical shape (or in any case, within the predetermined tolerances) makes it possible to minimize the risk that as a result of external stresses (such as earthquakes for example), the rotor 2 will start to rotate according to undesirable axes of rotation, causing a collision between the rotor 2 and the casing 3, due to the geometry of the rotor 2.

The rotor 2 preferably comprises a structure made of non-reinforced concrete, or in any case, made of a diamagnetic material. This makes it possible to prevent undesirable interactions with magnetic fields generated by the first and the second means 4, 5.

In a second operating mode, the second means 5 generate electrical energy, which brakes the rotor 2. In this manner, they restore the kinetic energy accumulated previously. In the first operating mode, the second means 5 thus operate as an electric motor and, in the second operating mode, the second means 5 operate as an electric generator.

The minimum distance between the casing 3 and the rotor 3, when fully operational in the first operating mode, is preferably less than 20 centimetres, advantageously between 5 and 13 centimetres.

The casing 3 conveniently defines an inner chamber 3 that receives the rotor 2.This chamber 31 is substantially spherical.

Preferably, the following could ideally be identified in the rotor 2:

-an upper portion that involves one third of the vertical extension of the rotor 2;

-a lower portion that involves one third of the vertical extension of the rotor 2;

-an intermediate portion between the upper portion and the lower portion. This subdivision could be entirely theoretical and not indicated by specific visible or measurable discontinuities in the body of the rotor 2.

The first means 4 are at least partly located in the lower portion and in the upper portion. The second means 5 are at least partly located in the intermediate portion.

The second means 5 are preferably absent from said lower portion and from said upper portion. Conveniently, the first means 4 are instead absent from said intermediate portion.

The rotor 2 preferably rotates about an axis that tends to realign itself along a predetermined direction, preferably a vertical direction. The rotor 2 comprises return means for returning the axis of rotation towards a predetermined direction (a substantially vertical direction).

The return means comprise for example an equatorial band 8, perpendicular to said vertical direction, and having a higher mean density with respect to poles 81 , 82 that lie at opposite ends along a direction perpendicular to the equatorial band 8. The accumulator 1 advantageously comprises at least a first pump 91 for depressurizing the space interposed between the rotor 2 and the casing 3.This makes it possible to reduce the air that is present, reducing the friction on the rotor 2. The accumulator 1 preferably comprises a second pump 92 for depressurizing the space interposed between the rotor 2 and the casing 3. The second pump 92 is an auxiliary pump and it is redundant with respect to the first one. It typically intervenes in the case of breakage or a malfunction of the first pump 91.

The accumulator 1 further comprises rapid stop means for rapidly stopping the rotation of the rotor 2, said means comprising:

-a tank 70 containing a fluid, typically a liquid, preferably of a non- Newtonian type;

-an inlet 71 for introduction of the fluid in an interspace 30 that lies between the rotor 2 and a surface of the casing 3 that surrounds and faces said rotor 2 (this surface is directly defined by the rotor 2 and the casing 3);

-detection means 72 for detecting an emergency signal and that determine introduction of said fluid into said interspace 30.

Advantageously, it is a viscoelastic dilatant fluid.

The detection means for detecting an emergency signal typically make it possible to identify a hazardous situation that requires the rotor 2 to be stopped immediately to prevent it from causing damage that could affect the casing 3, but above all the outside of the casing 3;for example in the case of an earthquake. The introduction of a fluid into the interspace 30 between the rotor 2 and the casing 3 brings about an increase in friction on the rotor 2, which is thus braked. Advantageously, the fluid is introduced in a liquid state and it tends to harden when subjected to the mechanical stress of the rotor 2 when the latter is moving, thereby increasing friction on the rotor 2.Advantageously, once the stress from the rotor 2 ends, it tends to return to a liquid state.

Intervention of the rapid stop means usually damages the accumulator 1 (such damage can also be very serious and therefore the use of the stop means must be limited to situations of actual danger).

The weight and dimensions of the rotor 2 can vary considerably. For example, the dimensions of the rotor 2 could be limited by the structural resistance of the rotor 2 itself, given the high rotational speeds to which it can be subjected. By way of example, the rotor 2 could have a diameter of 5 metres. Yet in a preferred solution, the rotor 2 could have a rotational speed ranging between 10000 and 15000 revolutions per minute. Furthermore, the rotor 2 can even reach a weight of several tons.

In one examplary, though not necessary, solution the casing 3 comprises two half-shells, which, in combination with each other, completely enclose the rotor 2.

The present invention achieves important advantages.

First of all, the shape of the rotor (which approximates a sphere) allows for better distribution of the first means 4, which interact magnetically. In this manner, a plurality of magnets of a commercial type can be used, thereby enabling cost savings and without being required to keep them at very low temperatures. Moreover, the shape of the rotor 2 makes it possible to minimize the risk that in the case of rotations according to undesirable axes of rotation (which for example could occur in the case of earthquakes), the casing 3 is damaged 3 and in addition, the realignment of the axis of rotation with the planned direction would be facilitated.

The invention thus conceived is susceptible to numerous modifications and variants, all of which falling within the scope of the inventive concept characterizing the invention. Moreover, all details may be replaced with other technically equivalent elements. Furthermore, the dimensions may be of any sort, according to needs.