The present invention refers to an inductive magnetic harvester electric generating device from vibrations with magnetic suspension and internal guide .

As known, an harvester is a device capable of capturing energy from external sources present in its surrounding environment (sun energy, thermal energy, kinetic energy from vibrations, etc.) and transform it into electric energy which can be exploited, for example, by other electronic user devices or systems. It is therefore clear how the environment advantageously is an abundant source of energy, which can be stored in common accumulators like batteries, capacitors and the like.

In particular, among the various energy sources which can be used, vibrations can advantageously be exploited for making harvester devices: in fact, when a device is subjected to vibrations, it is possible to use an inertial mass suitably connected to an electric transducer to transform kinetic energy into electric energy. In time, harvester devices have been developed, which are able to transform kinetic energy supplied by vibrations into electric energy by exploiting different types of operation, based, for example, on the piezoelectric principle, the electrostatic principle (by using capacitors with plane parallel faces) or the electromagnetic principle (by exploiting the electromagnetic induction phenomena) . Known harvester device are disclosed in US7498681, US7569952, US6984902, US2004075363, DE102009041023, KR20080046613, US2008129147,

WO2008085636, WO2011061215, US2011109102 ,

WO2011042611, O2009099658 , O2009039293,

US7839058, WO2008051322.

The mentioned devices are piezoelectric and inductive, kinetic energy harvester devices, which however do not show constructive features pointing out a magnetic suspension and the presence of a guide for the moving magnet in order to reduce the friction dampening between internal sliding guide of the moving magnetic element and moving magnetic element itself, in addition to the presence of suitable vents present on the levitation chamber which, together with the presence of the internal guide, allow reducing the fluidic dampening, so as to increase the mechanical power which can be transferred to the electric converting circuit.

The mentioned devices further have a supporting material or envelope arranged between the moving magnet and a winding made of conductive material: advantageously, in the present invention, the internal guide allows sliding the moving magnet and not inserting any material between the magnet itself and the winding made of conductive material in order to induce such a magnetic field as to optimise the concatenation between magnetic flux and winding coils, thereby actually increasing the electric power generated by the harvester.

Other examples of such known devices are disclosed in O2010014023, O2010037708, JP4684106, GB2447086, US2006139000, WO02103881.

In particular:

O2010014023 discloses a re-charger which exploits, through a magnetic system, the vibration kinetic energy of the movement of a mechanical suspension with spring generated by the body vibration of the person wearing such device; WO2010037708 discloses an harvester with cantilever, elastic piezoelectric beam and magnetic suspension which provides for the use of the mass of the electronic apparatus to be supplied as seismic mass: the generation frequency, anyway very high, depends on the beam stiffness and not on the involved masses;

JP4684106 discloses a circuitry for electromagnetic generators composed of a double winding cut by two magnets which have the same polarity at their interface: two magnets with the same polarity are still present at the ends, with respect to the faces of the moving magnet, and the equivalent mechanical system is a double mass/spring system in series) ;

GB2447086 discloses a re-charger whose operation is again based on the oscillation of a magnet with spring caused by the vibration excitation from a human body;

US2006139000 discloses a re-charger whose operation is based on the conversion of the wrist vibration energy: in such re-charger, the magnet slides on ball bearings and a generator mono-axial feature is present, which does not appear able to collect even a small part of the oscillation component in orthogonal movement;

O02103881 discloses a re-charger composed of a spherical magnet adapted to roll inside a tube, and therefore lacking any type of suspension;

US5347186 discloses an electric power generator through linear motion.

As already previously mentioned, also the known devices cited in this last part have no magnetic suspension and more in particular the asymmetrical suspension, the presence of an internal sliding guide of the moving magnetic element and the moving magnetic element itself, and the presence of suitable vents present on the levitation chamber and the asymmetrical magnetic constraint, individually or in combination, which allow, with respect to the known prior art, a modularity of the fluidic dampening and a decrease of frictions, in order to increase the harvester reliability and the mechanical power which can be transferred to the electric conversion circuit.

In the present invention, differently from mentioned devices, between the moving magnet and a winding made of conductive material no material is interposed, in order to optimise the concatenation between magnetic flux and winding coils.

Moreover, examples of harvester generators known in the art and of the magnetic inductive type are disclosed by TO2011A000694, TO2011A000843 and TO2011A000844.

In particular:

- TO2011A000694 discloses a self-supplied device with magnetic inductive harvester with asymmetrical magnetic suspension;

- TO2011A000843 discloses a magnetic inductive re- charger with asymmetrical magnetic suspension with repeated pulse;

- TO2011A000844 discloses a ski or trekking racket self-supplied by a magnetic inductive harvester with asymmetrical magnetic suspension.

Again, the mentioned harvester devices, though having an asymmetrical magnetic constraint, do not disclose the presence of an internal guide of the moving magnet in order to reduce the friction dampening between internal sliding guide of the moving magnetic element and the moving magnetic element itself, and the presence of suitable vents on the levitation chamber which, together with the presence of the internal guide, allow reducing the fluidic dampening, in order to increase the mechanical power which can be transferred to the electric converting transducer. The mentioned devices further have no winding made of conductive material in order to induce a magnetic field between the winding itself and the free moving magnetic element, namely without the presence of any material between the winding support and the moving magnetic element, in order to optimise the concatenation between magnetic flux and winding coils, thereby actually increasing the electric power generated by the harvester.

The art has further proposed, as possible applications in the field of monitoring vehicles and mechanical systems, biomedical and human interfaces applications, autonomous systems which use harvester devices for their energy self-supply: such systems are particularly interesting since, being energetically autonomous, they are able to operate even in environments which can be reached with difficulty by the traditional supply sources and are, therefore, a major solution in environments lacking supply mains or batteries. Systems supplied by harvester devices, which are known in the art are disclosed in O2010100582, US2006170217, MX2010001008 , US2010090656,

US2009309538, WO2009097485, KR20080031391.

In particular, Wireless Sensors Networks (WSN) supplied by harvester devices are currently the most interesting technology for monitoring both internal and external environments. The use of harvester devices in fact is the only possible solution to remove the need of supply mains and batteries, and to have available, in this way, autonomous sensor nodes, operating for long periods (theoretically indefinitely) , which, once installed, to not need any particular care ("fit and forget") .

The art however does not propose any self- supplied system, which embeds an improved, modified harvester device like the one of the present invention.

Documents WO-Al-2006/078084 , US-Al-

2010/117373, JP-A-2010 200479 and US-A1-2012/104877 disclose harvester devices according to the preamble of Claim 1.

Therefore, object of the present invention is solving the above prior art problems, by providing an improved magnetic inductive harvester device with magnetic suspension with internal guide, preferably with asymmetrical suspension, which allows improving prior art devices with traditional spring-type suspension, since the spring mechanical element is removed, which is subjected to breakage due to fatigue, increasing the device reliability and guaranteeing a longer stroke of the moving magnet in its oscillating motion, due to the presence of a single fixed magnet, which operates as suspension, and in which the moving magnet guide is internal and not external to the magnet itself, as instead occurs in prior known devices, in such a way as to minimise the dampening due to mechanical frictions between guide and magnet and to fluidic frictions, thereby maximising the mechanical power which can be transferred to the electric transducer (winding) , which results in a higher efficiency of the generator.

Moreover, an object of the present invention is providing an improved harvester device, which allows exploiting a greater amount of the vibration frequency spectrum with respect to what is proposed by the prior art.

Another object of the present invention is providing an improved harvester device in which the winding substantially has no dielectric material at the interface between moving magnet and winding, in order to maximise the concatenated magnetic flux on every single winding coil, thereby reducing the leakages as opposed to a better electric generation of the device itself.

Moreover, an object of the present invention is providing an improved magnetic inductive harvester device with internal guide and free winding without support coupled with means for transforming the generated electric energy adapted to transform the electric current from alternate to direct, in order to be able to transfer it, efficiently and with high efficiency, through a suitable rectifying circuit, preferably composed of a rectifying bridge and a circuit of the step-up / step-down type, so that every single energy contribution of electric power generated by the harvester device can be stored into suitable temporary electric accumulation means, adapted to store, at least temporarily, the electric energy produced by such harvester device.

Another application object of the present invention is providing a sensing and/or diagnostic system, for logistic and vehicle, mechanical and bio-mechanical applications, self-supplied by the above improved harvester device, which allows providing sensing, measuring and information locating and transmitting functionalities in a self-supplied mode and with the chance of an integrated multi-node interfacing.

The above and other objects and advantages of the invention, as will result from the following description, are obtained with an improved harvester device as claimed in Claim 1.

Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

It is clear that the enclosed claims are an integral part of the present description.

It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) can be made to what is described, without departing from the scope of the invention as appears from the enclosed claims.

The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which: Figure 1 shows a perspective view of a preferred embodiment of the magnetic inductive vibration electric generator device with internal guide and free winding without support according to the present invention;

Figure 2 shows a longitudinally sectioned view of the device of Figure 1;

Figure 3 shows a perspective view of a preferred embodiment of a component of the device according to the present invention;

Figures 4a and 4b show perspective and partially sectioned views of an alternative preferred embodiment of the device according to the present invention;

Figure 5 shows a perspective view of the device according to the present invention equipped with at least one integrated module self-supplied by the device according to the present invention;

Figure 6 shows a perspective view of the module of Figure 5 equipped with a containing envelope;

Figure 7 shows a diagram representing a network comprising one or more modules of Figures 5 and 6. In general, as can be seen below in more detail, the operation as electric generator from vibrations of the magnetic inductive harvester device 1 with internal guide and free winding without support is based on the magnetic inductive interaction between a moving magnetic element and a winding and a fixed magnetic suspension element.

Therefore, with reference to the Figures, it is possible to note that the harvester device 1 according to the present invention comprises:

at least one moving magnetic element 6, preferably equipped with at least one central through-hole, sliding along at least one internal sliding guide 7, preferably made of a non-magnetic material, such internal sliding guide 7 being preferably passing inside such hole of the moving magnetic element 6;

at least one fixed magnetic element 8 arranged in the vertically lower end of such internal sliding guide 7, such fixed magnetic element 8 and such moving magnetic element 6 sliding along such internal sliding guide 7 being mutually oriented in such a way as to oppose the two faces with the same polarity in order to generate a repulsion force actually making a magnetic suspension; at least one winding 9 formed of at least one first coil 10 made of electrically conductive material adapted to concatenate a magnetic field of such moving element 6 sliding along such internal sliding guide 7, preferably passing through the central hole of the element 6 itself.

The harvester device 1 according to the present invention can further comprise:

at least one spacer 11, preferably made of non-magnetic material, for supporting at least one winding 9 composed of at least one coil 10 made of electrically conductive material to actually make at least one levitation chamber 15 within which such moving magnetic element 6 slides, such levitation chamber 15 being equipped with at least one venting opening 16 to allow the fluid F, typically air, present inside the levitation chamber 5, to go out therefrom during the reciprocating motion of the moving magnetic element 6 in order to reduce the fluidic dampening; alternatively to the presence of the venting opening 16, it is possible to provide that vacuum is created inside such chamber 15; at least one base 12, preferably made of nonmagnetic material, in which such internal sliding guide 7 is inserted;

at least one containing envelope 2 for such harvester device 1, such envelope being preferably made of non-magnetic material.

Preferably, such internal sliding guide 7 is arranged longitudinally and in parallel to the sliding direction of the moving magnetic element 6 inside the chamber 15.

Preferably, such levitation chamber 15 has a cylindrical shape (similar to a tube) .

According to a preferred embodiment of the harvester device 1 according to the present invention, such winding 9, composed of at least one first coil 10 made of electrically conductive material adapted to concatenate the magnetic field of the moving magnetic element 6, is substantially in direct contact with the moving magnetic element 6, having a section which is not much bigger than the section of the moving magnetic element 6 since, when building such winding 9, it is wound on a preferably cylindrical removable support, whose size is not much bigger than the size of the moving magnetic element 6 and inserted around this latter one, this allowing to have, at the end of the procedure, namely after having extracted the support for making the winding 9, at least one winding 9 composed of at least one coil 10 directly interfaced with the moving magnetic element 6 apart from the tolerance which its sliding without interference implies, and therefore without a dielectric material interposed between the moving magnetic element 6 and the winding 9.

Alternatively, always in order to minimise the magnetic flux leakages concatenated between moving magnetic element 6 and winding 9, such winding 9 is made by using at least one winding cage 14 of such coil 10, the cage 14 being arranged along the spacer 11 in order to be a perimeter portion thereof and being composed of at least one winding structure of the coil 10, such structure being equipped with a plurality of slits 13. In particular, the slits 13 present on the cage 14 allow making a direct concatenation of the coil 10 with the magnetic field generated by the moving magnetic element 6 without interposing material. Preferably, therefore, the cage 14 is made of a non-magnetic material with internal sizes not much greater than the internal sizes of the moving magnetic element 6, in order to allow its sliding inside the chamber 15 formed by cage 14 and spacer 11 without interference. The presence of the cage 14 keeps unchanged the advantages of the embodiment with removable support, since the presence of the slits 13 of the cage 14 minimises the magnetic flux leakages concatenated between moving magnetic element 6 and coil 10.

Therefore, when the harvester device 1 according to the present invention is stressed by an external vibration force, due to actually be adapted to be schematised with a mass-spring model, wherein the seismic mass is given by the mass of the moving magnetic element 6 and the spring is given by the asymmetrical magnetic suspension, between moving magnetic element 6 and winding 9 made free without support, a relative motion occurs, which is translated into an electromotive force induced on the winding 9 itself.

Since the moving magnetic element 6 slides along the guide 7 arranged internally and not externally like in known harvester devices, the friction coefficient between guide 7 and moving magnetic element 6 is reduced by the ratio between external/internal contact surfaces; this implies a reduction of the mechanical dampening. As regards the fluidic dampening, this is removed through the vent openings 16 on the spacer 11 supporting the winding 9 that makes the levitation chamber 15; the presence of vent openings 16 on the spacer 11, together with the presence of the sliding guide 7 of the moving magnetic element 6, actually removes the "plunger" effect which the moving magnetic element 6 itself performs in its motion when the external diameter of such moving magnetic element 6 and the internal diameter of the guide 7 are equal, apart from the tolerance that allows their sliding without interference. This arrangement allows transferring a greater mechanical power, which can be transferred to the electric transducer (winding 9) with a following increase of the generated electric power.

In another alternative embodiment like the one, for example, shown in Figures 4a and 4b, the harvester device 1 according to the present invention comprises, in particular, a plurality of such chambers 15, each one of such chambers 15 being equipped with related moving magnetic element 6, fixed magnetic element 8, guide 7 and winding 9 as previously described, in order to make a generator with a wider spectrum of energy conversion frequency from vibrations, advantageously converting the electric energy produced by the different windings 9 in the same electronic step-up/step-down alternate/direct conversion circuit 4.

Preferably, such magnetic levitation chambers 15 of the above plurality are arranged side by side in parallel, such magnetic levitation chambers 15 further having mutually different and suitably dimensioned diameters. Obviously, each fixed magnetic element 8 and each respective moving magnetic element 6 has shape and sizes compatible with shape and sizes of the respective magnetic levitation chamber 15 within which it is placed. In particular, such moving magnetic elements 6 have mutually different and suitably computed heights.

Due to their intrinsic nature, vibrations of vehicles, transport means or parts thereof are characterised by rather wide spectra, whose part with energy content is concentrated at medium-low frequencies (lower than 100-200Hz) . The excitation vibration frequency is continuously variable in time, depending on several parameters, such as, among others, structural properties of the means and its parts, path characteristics, speed, etc. The presence, inside the harvester device 1 according to the present invention, like the one of the variation of Figures 4a and 4b, of a series of moving magnetic elements 6 oscillating along their respective chamber 15 and having different geometries (and therefore resonance frequencies) , allows suitably covering the bandwidth of interest and advantageously maximising the electric generation on at least one of the coils 10 under any working condition.

The harvester device 1 according to the present invention can further comprise, possibly also arranged inside the envelope 2:

temporary electric accumulation means 5 comprising for example at least one backup battery; transforming means 4 of the generated electric energy adapted to transform the electric voltage from alternate to direct in order to be able to highly efficiently transfer it to the temporary electric accumulation means 5;

managing means: in particular, such managing means comprise electric current rectifying means, such rectifying means preferably comprising diode bridges and integrated circuits of the step-up / step-down type in a number equal to the chambers 15: alternatively or additionally, such managing means can comprise electric current stabilising means, preferably comprising capacitors in a number equal to the chambers 15.

Each one of the coils 10 arranged around their respective chamber 15 is thereby connected to a related diode bridge and a related integrated circuit of the step-up / step-down type, which, in turn, is connected, possibly by interposing an integrated circuit of the step-up / step-down type and/or a capacitor and/or the transforming means 4, to the electric accumulation means 5.

Moreover, the supporting and containing structure 2 can also be equipped with displaying means (not shown) , composed for example of at least one switch connected to a luminous LED, which allow verifying the presence of charge inside the backup battery 5 above a prefixed threshold.

Once having subjected the harvester device 1 according to the present invention to vibrations, the moving magnetic element (s) 6 being levitating, stressed by the external force of such vibration, trigger their oscillating motion and produce the generation of electric current inside their respective coils 10. The produced current is of the alternate type, with frequency changing in time and identical to the vibration frequency of each moving magnetic element 6. Such current is rectified, for example by means of the diode bridge, stabilised for example by means of the capacitor and finally accumulated in the electric accumulation means 5, whose charge level progressively increases. As stated, preferably, such current is transformed from alternate to direct by the transforming means 4 before being transferred to and stored into the electric accumulation means 5.

Therefore, differently from prior art harvester generating devices, the harvester device 1 according to the present invention has the following peculiar features and their related advantages :

for generation, it exploits the magnetic flux concatenation between moving magnetic element 6 and winding 9 without any dielectric at the interface between the two elements (moving magnetic element 6 and winding 9) in order to increase the generated power;

the moving magnetic element 6, being preferably internally drilled and being guided by the internal sliding guide 7 passing along such hole, allows reducing the guide/magnet friction coefficient by the ratio between the external/internal contact surface with respect to the external guided moving magnets used for known harvester devices; this implies a reduction of the mechanical dampening;

the configuration of the internal sliding guide 7, joined to the presence of the vent openings 16 on the spacer 11 supporting the winding 9, implies a reduction also of the fluidic dampening, allowing a higher mechanical power which can be transferred to the winding 9 and a consequent increase of the generated electric power;

the variation without a magnet placed on the upper part of the chamber 15, like in some prior art harvester devices, and with only the fixed magnetic element 8 arranged on the bottom and suitably oriented, allows actually making an asymmetrical magnetic suspension with the moving magnetic element 6, allowing to increase the stroke of the moving magnetic element 6 through the winding 9 when the device 1 is subjected to vibration: this arrangement implies an improvement of the prior art as regards the generation of electric power with respect to the solution with symmetrical magnetic suspension;

the presence of the suitably oriented fixed magnetic element 8 so to actually make an asymmetrical magnetic suspension with the moving magnetic element 6, allows doing without the spring element, subjected to breakage due to the fatigue present in prior art generators, thereby actually improving the prior art;

the asymmetrical magnetic suspension obtained between fixed magnetic element 8 and moving magnetic element 6 is characterised by a very small stiffness with respect, for example, to the stiffness of the spring-type mechanical suspensions of prior art harvester devices; this allows making magnetic transducers oscillating at low frequencies (namely those of interest for the operating conditions), reducing the masses and therefore the global sizes of the harvester device 1 according to the present invention.

As it is possible to note in particular in Figures 5 and 7, the harvester device 1 according to the present invention can be operatively coupled with at least one detecting means 3 equipped with wireless transmission means 18 for detected data, such harvester device 1 being then adapted to supply with electric current such detecting means 3 and such wireless transmission means 18 in order to make a self-supplied integrated module 20 for measuring and transmitting data, aimed to the function of measuring and monitoring physical parameters of mechanical and bio-mechanical systems which are moving and on board vehicles, without the need of a cable-type electric connection, nor the presence of energy reserves, such as, for example, backup batteries or suitably sized temporary accumulation systems 5.

In particular, Figure 7 shows a self-supplied multi-node network "sensing wireless" system 30 comprising a plurality of such modules 20 according to the present invention, each one of such modules composing a node of this system 30, such system 30 being in particular aimed to monitor physical parameters of moving systems and to transmit data.

Advantageously, as it is possible to note in particular in Figure 6, at least the harvester device 1, the detecting means 3 and the related wireless transmission means can be contained inside the same containing envelope 2 in order to make the module 20 capable of converting the kinetic energy of vehicle vibrations into electric energy, thereby making available for users an unlimited and autonomous reserve obtained from external sources.

Obviously, the type of detecting means 3 is variable and depending on their function: in fact, they can be composed of sensors of various nature, depending on the number and type of environmental parameters to be measured, with related control and conditioning electronics, GPS antennas for a geo- referenced location, etc.

In addition, it is possible to provide for a replica also or only of the integrated self-supply and data transmission module 20 in many positions on a vehicle, making it possible to identify each one of such modules as one of the nodes of the multi-node system 30.

It will be wholly clear for the skilled person in the art that the application purposes of such system are multiple and can range from the simple monitoring of on-board parameters in positions which can be reached with difficulty by traditional measuring and sensing systems, above all due to the electric supply difficulties, such as, for example, temperature and acceleration, to the space location of the mechanical object to be monitored for geo- referencing and inertial navigation purposes.

The module 20 according to the present invention is therefore able, in a way which is self-supplied by environmental vibrations through the harvester device 1, to detect and transmit outside, through the wireless transmission means, some type of physical quantities detected by the detecting means 3, such transmission being addressed to transceiver bridge means 31 belonging to such system 30.