WO2014170922A1 - Multi-frequency vibration piezoelectric harvester device - Google Patents

Multi-frequency vibration piezoelectric harvester device Download PDF

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Publication number
WO2014170922A1
WO2014170922A1 PCT/IT2014/000096 IT2014000096W WO2014170922A1 WO 2014170922 A1 WO2014170922 A1 WO 2014170922A1 IT 2014000096 W IT2014000096 W IT 2014000096W WO 2014170922 A1 WO2014170922 A1 WO 2014170922A1
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WO
WIPO (PCT)
Prior art keywords
small
piezoelectric
oscillating small
previous
oscillating
Prior art date
Application number
PCT/IT2014/000096
Other languages
French (fr)
Inventor
Andrea Tonoli
Nicola Amati
Enrico Cesare Zenerino
Roberto BONIN
Alessandro RAPISARDA
Emanuele PENSAVALLE
Original Assignee
Politecnico Di Torino
Aviospace S.R.L.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to ITTO20310301 priority Critical
Priority to ITTO2031A000301 priority
Application filed by Politecnico Di Torino, Aviospace S.R.L. filed Critical Politecnico Di Torino
Publication of WO2014170922A1 publication Critical patent/WO2014170922A1/en

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L41/00Piezo-electric devices in general; Electrostrictive devices in general; Magnetostrictive devices in general; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L41/08Piezo-electric or electrostrictive devices
    • H01L41/113Piezo-electric or electrostrictive devices with mechanical input and electrical output, e.g. generators, sensors
    • H01L41/1134Beam type
    • H01L41/1136Cantilevers
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02NELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00Electric machines in general using piezo-electric effect, electrostriction or magnetostriction
    • H02N2/18Electric machines in general using piezo-electric effect, electrostriction or magnetostriction producing electrical output from mechanical input, e.g. generators
    • H02N2/186Vibration harvesters
    • H02N2/188Vibration harvesters adapted for resonant operation

Abstract

A multi-frequency vibration piezoelectric harvester device (1) is described, comprising at least one supporting structure (3) for connection with the external environment, at least one main oscillating small beam (5) comprising at least one element with piezoelectric effect, at least one dynamic amplifier (2) arranged between such main oscillating small beam (5) and such supporting structure (3), such dynamic amplifier (2) being adapted to create at least two resonant frequencies cooperating with such main oscillating small beam (3).

Description

MPLTl-FtU½0¾NCY νΐήΚλΐΐσ» fiaZOKLECTRlC HARVESTER DEVICE
The present invention deals with a multi- frequency vibration piezoelectric harvester device.
As known, there are devices, also known as "energy harvesters", which are able to capture energy from external sources present in the surrounding environment (sun energy, thermal energy, kinetic energy from vibrations, etc.) and transform it into exploitable electric energy, for example, from other user devices or electronic systems such as, for example, sensors and micro- sensors. It is thereby clear how the environment advantageously represents an abundant source of energy, if compared with the amount of energy which can be stored in common accumulators such as batteries, capacitors and the like.
In particular, among the various energy sources which can be used, vibrations can be advantageously exploited to make 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. Therefore, harvester devices have been developed in the years which are equipped with linear oscillating mechanical systems capable of transforming the kinetic energy provided by vibrations into electric energy through capacitive, inductive or piezoelectric transducers. In particular, the physical phenomenon on which harvester devices with piezoelectric operation are based consists in generating electric voltage in particular materials when they are subjected to an external mechanical stress (compression, traction, flexure, torsion) . The effect is reversible: in fact, if a potential difference is applied to the same material, this contract or expands.
Currently, mechanical oscillators are designed so that their resonant frequency is near to dominating frequencies typical of mechanical vibrations characterizing the particular environmental context. In many real cases, however, such solutions show a rathe low efficiency since frequencies characteristic: of mechanical vibrations usually cover a very wide range of frequencies. In particular, environmental vibrations are due to strongly heterogeneous sources such as, for example, vibrations induced by turbulent fluid- dynamic flow, seismic noise vibrations causes by reaction motors or the motion of ehicles on a surface with random outline. The difficulties in conceiving wide band harvester devices therefore resides in that for the above situations, it is not possible to define one or more resonant frequencies which are characteristic of the system, since, depending on the features of the vibration, there will be instead a certain number of peaks in the power spectral density of the stress. In general, it is however possible to demonstrate that, for stresses characterized by very distributed spectral densities, the response of a wide band oscillator is energetically more advantageous if compared with that of a mono-frequency resonant oscillator.
Therefore, object of the present invention is solving the above prior art problems, by providing a multi-frequency vibration piezoelectric harvester device capable of generating electric energy by exploiting, through a piezoelectric effect, vibration stresses characterized by very distributed spectral densities, thereby increasing the range of applications of the device.
Another object of the present invention is providing a multi-frequency vibration piezoelectric harvester device capable of exploiting a wide band vibration excitation generating a higher power and more efficiently with respect to prior art devices.
Moreover, an object Of the present invention is providing an harvester device whose sizes are more compact with respect to what is proposed by the prior art.
The above and other objects and advantages of the invention, as will appear from the following description, are obtained with an 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 intended that all 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 top perspective view of the harvester device according to the present invention; and
Figure 2 shows a graph related to a transfer function of the harvester device according to the present invention.
With reference to Figure 1, it is possible to note that the multi-frequency vibration piezoelectric harvester device 1 according to the present invention comprises:
at least one supporting structure 3 for connection with the external environment;
at least one main oscillating small beam 5 comprising at least one element with piezoelectric effect adapted to convert the mechanical vibration energy to which the device 1 according to the present invention is subjected, into electric energy. For example, such element with piezoelectric effect is at least one plate 6 made of piezoelectric material arranged on at least one surface thereof: preferably, such main oscillating small beam 5 has both its opposite surfaces equipped with such plates 6 made of piezoelectric material in order to increase the produced electric energy;
at least one dynamic amplifier 2 arranged between such main oscillating small beam 5 and such supporting structure 3, such dynamic amplifier 2 being adapted to create at least two resonant frequencies, which delimit the range of frequencies in which the device is efficient in converting vibration energy, cooperating with such main oscillating small beam 3.
Preferably, such main oscillating small beam 5 is placed in an engaged-free configuration, thereby having at least one free end with respect to the supporting structure 3 of the device 1 according to the present invention.
Preferably, the main oscillating small beam 3 is made of an elastic material (for example steel or aluminium) .
Preferably, the main oscillating small beam 5 is equipped with at least one first seismic mass 7 placed next to the free end of the small beam 5 itself, the purpose of such seismic mass 7 being lowering the natural oscillating frequencies of such main oscillating small beam 5 and increasing the dampening of the oscillations.
As known, in fact, a piezoelectric harvester device, like the prior art ones, equipped only with a small oscillating beam has a well determined oscillating frequency of the first modal shape: usually, the following modal shape is excited at a frequency of a greater order of magnitude, making thereby scarcely efficient to use the small beam when external vibrations have a wide but limited frequency spectrum. In order to pass such limit, the harvester device 1 according to the present invention therefore comprises the dynamic amplifier cooperating with the main oscillating small beam 5 to create at least the two relatively near excitation frequencies.
Preferably, such dynamic amplifier 2 is a mass-^spring-dampener system comprising at least two secondary oscillating small beams 4a, 4b, each of which comprises at least one element with piezoelectric effect adapted to convert the mechanical vibration energy to which the device 1 according to the present invention is subjected, into electric energy, and having a first end connected to such supporting structure 3 and a second end opposite to such first end connected to at least one second seismic mass 9, such main oscillating small beam 5 having an opposite end to its free end connected to such second seismic mass 9.
Also in this case, for example, such element with piezoelectric effect is at least one plate 8 made of piezoelectric material arranged on at least one surface of such secondary oscillating small beam 4a, 4b: preferably, each of such secondary oscillating small beams 4a, 4b has both its opposite surfaces equipped with such plates 8 made of piezoelectric material i order to increase the produced electric energy: obviously, the piezoelectric elements, and in particular the plates 6, 8 made of piezoelectric material, can be connected in series or in parallel, if voltage or current output from device 1 according to the present invention has respectively to be increased.
Therefore, it must be noted how, advantageously, the device 1 according to the present invention provides an increase of the generated power also due to the use of many piezoelectric elements, such as for example the piezoelectric plates 6, 8, arranged both on the main oscillating small beam 5 and on the secondary oscillating small beams 4a, 4b of the dynamic amplifier 2.
In the preferred embodiment of the device 1 according to the present invention, the main oscillating small beam 5 is arranged as an exemple in a position interposed between the secondary oscillating small beams 4a, 4b: obviously, though keeping the same operating principle described above, numerous alternative configurations are possible without thereby departing from the scope of the present invention. For example, the main oscillating small beam could be divided and arranged outside the dynamic amplifier: in this case, the two main oscillating small beams could be synchronized on different frequencies, in order to obtain a global response with three resonance peaks and therefore a further widened band.
A further alternative can exploit a geometry with many planes of symmetry.
Moreover, it must be noted how the configuration of the device 1 according to the present invention as proposed above, can be used not only for embodiments with conventional technologies, but also for a miniaturization through technologies typical of the semiconductor industry.
As an example, the device 1 according to the present invention has been described above taking into account double-frequency oscillating systems. An example of a transfer function of this device 1 is therefore shown in Figure 2, in which as input there is the acceleration spectrum of mechanical vibrations applied to the supporting structure 3 while as output there is he produce voltage. Resonance peaks (a) and (b) generated by the presence of the dynamic amplifier 2 are shown: these two peaks are placed on the sides of the single resonance peak which would be produced by the main oscillating small beam 5 only. When there is the dynamic amplifier 2, this single peak is depressed while the two peaks (a) and (b) appears. A system having a divided excitation peak generates a higher power with respect to that of a single- peak system, since the delivered power is proportional to the area subtended by the curve described by the transfer function: such area, with the same height, is greater when there is a divided peak, as can be seen in Figure 2.

Claims

1. Multi-frequenc vibration piezoelectric harvester device (1) characterized in that it comprises:
- at least one supporting structure (3) for connection with an external environment;
at least one main oscillating small beam (5) comprising at least one element with piezoelectric effect;
- at least one dynamic amplifier (2) arranged between said main oscillating small beam (5) and said supporting structure (3), said dynamic amplifier (2) being adapted to create at least two resonant frequencies cooperating with said main oscillating small beam (3) .
2. Device (1) according to claim 1, characterized in that said element with piezoelectric effect is at least one plate (6) made of piezoelectric material arranged on at least one surface of said main oscillating small beam (5) .
3. Device (1) according to th previous claim, characterized in that said main oscillating small beam (5) has both its opposite surfaces equipped with said plates (6) made of piezoelectric material .
4. Device (1) according to the previous claim, characterized in that said main oscillating small beam (5) is placed in an engaged-free configuration, having at least one free end with respect to said supporting structure (3) *
5. Device (1) according to the previous claim, characterized in that said main oscillating small beam (5) is equipped with at least one first seismic mass (7) placed next to said free end of said small beam (5) .
6. Device (1) according to any one of the previous claims, characterized in that said dynamic amplifier (2) is a mass-Spring-dampener system comprising at least two secondary oscillating small beams (4a, 4b) , each of said secondary oscillating small beams (4a, 4b) comprising at least one element with piezoelectric effect and having a first end connected to said supporting structure (3) and a second end opposite to said first end connected to at least one second seismic mass (9), said main oscillating small beam (5) having an opposite end to its free end connected to said second seismic mass (9) .
7. Device (1) according to the previous claim, characterized in that said element with piezoelectric effect is at least one plate (8) made of piezoelectric material arranged on at least one surface of said secondary oscillating small beam (4a, 4b) .
8. Device (1) according to the previous claim, characterized in that each of said secondary oscillating small beams (4a, 4b) has both its opposite surfaces equipped with said plates (8) made of piezoelectric material.
9. Device (1) according to any one of the previous claims, characterized in that said main oscillating small beam (5) is arranged in a position interposed between said secondary oscillating small beams (4a, 4b).
10. Device (1) according to any one of claims 1 to 6, characterized in that said main oscillating small beam is divided and arranged outside said dynamic amplifier.
11. Device (1) according to the previous claim, characterized in that said secondary oscillating small beams (4a, 4b) are tuned on different frequencies.
PCT/IT2014/000096 2013-04-15 2014-04-03 Multi-frequency vibration piezoelectric harvester device WO2014170922A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
ITTO20310301 2013-04-15
ITTO2031A000301 2013-04-15

Publications (1)

Publication Number Publication Date
WO2014170922A1 true WO2014170922A1 (en) 2014-10-23

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104993738A (en) * 2015-07-09 2015-10-21 清华大学深圳研究生院 Piezoelectric power collector
JP6474868B1 (en) * 2017-08-29 2019-02-27 株式会社トライフォース・マネジメント Power generation element
CN109428511A (en) * 2017-08-25 2019-03-05 青岛因菲尼思微电子科技有限公司 A kind of vibrational energy collector of multistage coupled structure

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120074812A1 (en) * 2009-06-26 2012-03-29 Murata Manufacturing Co., Ltd. Piezoelectric Power Generator and Wireless Sensor Network Apparatus
WO2012137695A1 (en) * 2011-04-07 2012-10-11 株式会社村田製作所 Piezoelectric power generator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120074812A1 (en) * 2009-06-26 2012-03-29 Murata Manufacturing Co., Ltd. Piezoelectric Power Generator and Wireless Sensor Network Apparatus
WO2012137695A1 (en) * 2011-04-07 2012-10-11 株式会社村田製作所 Piezoelectric power generator
EP2662971A1 (en) * 2011-04-07 2013-11-13 Murata Manufacturing Co., Ltd. Piezoelectric power generator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104993738A (en) * 2015-07-09 2015-10-21 清华大学深圳研究生院 Piezoelectric power collector
CN109428511A (en) * 2017-08-25 2019-03-05 青岛因菲尼思微电子科技有限公司 A kind of vibrational energy collector of multistage coupled structure
JP6474868B1 (en) * 2017-08-29 2019-02-27 株式会社トライフォース・マネジメント Power generation element

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