KR101232629B1 - self resonant frequency tunable vibration energy converting device, cantilever vibrator available at this and method for fabrication thereof - Google Patents

Abstract

Disclosed is a vibration energy converter capable of self-adjusting a resonance frequency. In the vibration energy conversion device capable of self-adjusting the resonant frequency according to the embodiment of the present invention, in the vibration energy conversion device using the cantilever, first and second cantilever beams having different lengths having free ends facing in opposite directions are provided. Cantilever vibrating body; And a cantilever fixture which is coupled to the cantilever interpolation portion of the cantilever vibrator having a contact surface that is capable of restraining bending deformations of the first and second cantilever beams and guiding the cantilever vibrator to be movable in a horizontal direction.

Description

Self resonant frequency tunable vibration energy converting device, cantilever vibrator available at this and method for fabrication

The present invention relates to a small energy conversion device for converting vibration generated in everyday life into electrical energy, and more particularly, to a vibration energy conversion device that can automatically change the natural frequency in response to changes in external vibration frequency. .

With the development of information and communication technology, mobile communication devices and portable terminals are widely used. When the rechargeable battery is used as a power supply means of these devices, power for charging the rechargeable battery is required. In a place where no facility for charging is provided, such as outdoors, power supply is difficult, and thus the use of the rechargeable battery is restricted.

In order to solve this inconvenience, a small generator for charging a rechargeable battery even in a place where a separate power supply is not provided has been proposed in various structures, the energy for generating electricity using a piezoelectric element as a proposed technology for this purpose. Conversion techniques are disclosed.

In general, when a piezoelectric force is applied in a specific direction from the outside, a positive charge is induced on one electrode and a negative charge is induced on the other electrode to generate a voltage between the two electrodes. The phenomenon is called the piezoelectric positive effect. On the contrary, the phenomenon in which the piezoelectric body causes mechanical distortion by applying a voltage to the piezoelectric body is called a piezoelectric adverse effect.

The piezoelectric body has been developed in various structures as a power generating device that generates electricity by using a property of converting a mechanical force (stress) into an electrical signal (voltage) or an electrical signal into a mechanical force as described above.

The energy conversion efficiency of the vibratory energy harvesting device is maximized when the frequency of the surrounding vibration matches the resonant frequency of the harvesting device. Since the frequency of the daily vibration sources is mostly time variant, it is effective in such a time-varying frequency vibration environment. In order to convert energy, a self tuning technique that adjusts the resonant frequency of the harvesting device in real time and automatically is required.

Resonant frequency tuning techniques of energy harvesting devices can be classified into active tuning and passive tuning.

Active tuning using piezoelectric actuators and the like consumes energy at all times to maintain and control the tuned frequency, while passive tuning using movable proof mass and the like tunes the tuned resonance frequency. There is no additional energy consumption to maintain and control.

However, according to the manual tuning, since the tuning of the resonant frequency is manually performed in the state where the operation of the energy harvesting device is stopped, it has to be restarted again, and thus it is difficult to tune in real time according to the change of the surrounding frequency.

According to these prior arts, when the resonant frequency of the energy converter is determined in the design process of the converter, the resonant frequency of the energy converter can be changed without relying on separate physical, electrical and electronic control elements as described above. As a result, energy conversion cannot be effectively implemented in a time-varying frequency vibration environment.

The present invention devised to solve the problems described above, the resonant frequency is adjusted in real time and automatically according to the external vibration frequency without using a separate physical, electrical, electronic control element and effectively energy in a time-varying frequency vibration environment An object of the present invention is to provide a vibration energy converting apparatus that can be converted, a cantilever vibrating body usable therein, and a manufacturing method thereof.

The present invention for achieving the object as described above, in the vibration energy conversion device using a cantilever, the cantilever vibrating body is provided with the first, second cantilever (110, 120) of different lengths in which the free ends are directed in opposite directions 100; And a contact surface capable of restraining bending deformation of the first and second cantilever beams 110 and 120, coupled to the cantilever interpolation connection 130 of the cantilever vibration body, and capable of moving the cantilever vibration body 100 in a horizontal direction. The cantilever fixed body 200 to guide the guide; and a vibration energy converter capable of self-adjustment of the resonant frequency including the technical gist.

The cantilever vibrating body 100 may include a piezoelectric polymer such as polyvinylidene fluoride (PVDF).

In addition, the cantilever vibrating body 100 includes: a first cantilever group (110C) formed by arranging a plurality of the first cantilever (110) in series; And a plurality of second cantilever groups 120C formed by continuously arranging a plurality of the second cantilever 120s.

In addition, the cantilever vibrating body 100 is formed of a conductive material capable of forming a movement path of polarized charges in the first and second cantilever beams 110 and 120, so that the first cantilever beam 110 and the second cantilever beam are formed. An electrode 140 coupled to one or both surfaces of the cantilever 120 may be further included.

In addition, the cantilever vibrator 100 may further include a proof mass 150 coupled to free ends of the first cantilever 110 and the second cantilever 120.

In addition, the cantilever vibrating body 100 may be selectively constrained to a portion of the fixed end side of the first and second cantilever beams 110 and 120 according to a relative position on the cantilever fixture 200.

In addition, the cantilever fixture 200 is formed with a guide groove 211 for reciprocating the cantilever interlocking connection 130 of the cantilever vibrating body in the longitudinal direction of the first and second cantilever beams 110 and 120. Guide unit 210; And a slit-shaped space coupled to the guide part 210 with the cantilever vibrating body 100 interposed therebetween, and capable of restraining vertical bending deformation of the cantilever vibrating body 100 together with the guide groove 211 of the guide part. And a fixing part 220 forming a part and a contact surface.

In addition, the slit 131 extending in the longitudinal direction of the first and second cantilever beams 110 and 120 on the cantilever interpolation connecting portion 130 of the cantilever vibration body; And a bump 212 protruding from the guide groove 211 to penetrate the slit 131 to form a horizontal movement limit of the slit 131.

In addition, ribs (132) protruding in a direction perpendicular to the longitudinal direction of the first, second cantilever (110, 120) on the cantilever interlocking portion 130 of the cantilever vibrating body; And an extension guide groove 213 formed at a designated width at a position corresponding to the rib 132 on the cantilever fixture 200 to form a horizontal movement limit of the rib 132. .

In addition, the first cantilever 110, the shortest length of the length range that is stretched and deformed by the horizontal movement of the cantilever vibrating body 100 may have a length longer than the longest length of the second cantilever 120. have.

In addition, a first operating state in which the cantilever vibrating body 100 is moved to one side of the cantilever fixture 200 such that the first cantilever 110 has the longest length; And a second operating state in which the cantilever vibrating body 100 is moved to the other side of the cantilever fixing body 200 so that the second cantilever 120 has the longest length.

In addition, the present invention, in the vibration energy conversion device using a cantilever, cantilever beams 110 and 120 having different lengths connected to free ends toward each other are provided, and the cantilever beam according to a change in an external vibration frequency ( The vibration energy conversion device capable of self-adjustment of the resonant frequency, including; cantilever vibrating body 100 that is automatically sliding and shifted in phase by the inertia force difference between 110 and 120 as another technical gist.

Here, the cantilever vibrating body 100, the position of the fixed end of the cantilever beam (110, 120) varies depending on the sliding movement position and the length and natural frequency of the cantilever beam (110, 120) can be changed.

In addition, the present invention, in the cantilever vibrating body 100 of the vibration energy conversion device using the cantilever, the first cantilever 110; A second cantilever 120 having a length different from that of the first cantilever 110 and having a free end facing in a direction opposite to the first cantilever 110; Cantilever vibration of the vibration energy conversion device comprising; and the cantilever interlocking portion 130 interconnecting the fixed ends of the first cantilever 110 and the second cantilever 120 and having a continuous outer surface slidable in one direction. Sieve 100 is another technical gist.

In addition, the present invention, in the method for manufacturing a vibration energy conversion device using a cantilever, the first and second cantilever beams 110 and 120 of different lengths having the free ends toward the opposite direction by patterning the film-type piezoelectric element is provided A structure forming step of manufacturing a cantilevered structure 100a having a shape; An electrode forming step of forming an electrode 140 by coating a conductive material on a surface of one or both sides of the first cantilever 110 and the second cantilever 120 of the cantilever structure 100a; And a mass coupling step of coupling a proof mass 150 to an end of the cantilever structure 100a to complete a frame of the cantilever vibrator 100. Make a point.

Here, after the mass coupling step, the guide groove 211 for guiding the bent interpolation connecting portion 130 of the cantilever vibrating body in the horizontal direction with the restrained contact surface of the first, second cantilever (110, 120) A cantilever coupling step of coupling on the cantilever fixture 200 provided with a; may further include.

According to the present invention according to the above configuration, the cantilever vibrating body is automatically moved by the cantilever interpolation centrifugal force difference according to the change of vibration frequency of the external environment, and the operation of the cantilever beam also provided in the cantilever vibrating body is also stretched and changed. The principle will be implemented.

Accordingly, the resonant frequency of the cantilever can be changed and adjusted in real time and automatically according to the vibration frequency of the external environment without a separate physical, electrical, or electronic external control element, and is not limited to a specific frequency band. I) Energy harvesting can be implemented over a frequency band.

1-A conceptual diagram showing a first operating state of a vibration energy conversion apparatus capable of self-adjusting the resonant frequency according to the first embodiment of the present invention
2 is a conceptual diagram showing a second operating state of a vibration energy converter capable of self-adjusting a resonance frequency according to a first embodiment of the present invention;
3-longitudinal sectional view of the main part of FIGS.
4a, 4b, 4c-conceptual diagram showing the manufacturing process of the cantilever vibrating body
5-conceptual diagram showing a cantilever fixture manufacturing process
Figure 6-exploded perspective view showing the process of assembling the cantilever vibrating body to the cantilever fixture
7 is a photograph of a vibration energy conversion device manufactured according to an embodiment of the present invention.
8-Photographed image of the rib moving state in the process of switching from the first operating state to the second operating state
9-a photograph photographing the rib moving state in the process of switching from the second operating state to the first operating state
10-Photographed image of the first cantilever in equilibrium
11-Photographed image of the first cantilever beam bent downward maximum
12-Picture photographing a state in which the first cantilever is bent upwardly
Fig. 13-A conceptual diagram showing the movement trajectory, horizontal and vertical displacement of the end portion according to the bending deformation of the cantilever beam
14 is a conceptual diagram showing an inertial force acting according to the vibration of the first and second cantilever beams in the vibration energy converter according to the embodiment of the present invention.
FIG. 15 is a photograph of an experimental apparatus for resonant frequency variation characteristics of a vibration energy converter according to an exemplary embodiment of the present invention. FIG.
Figure 16-schematic diagram of Figure 15
17-A graph showing the horizontal inertial forces acting on the first and second cantilever beams according to frequency bands in a first operating state.
18-A graph showing the inertial forces in the horizontal direction acting on the first and second cantilever beams according to frequency bands in a second operating state.
19-In accordance with the time of the first cantilever beam in the process of switching to the second operating state by increasing the external vibration frequency in the first operating state, and switching to the first operating state by decreasing the external vibration frequency in the second operating state. Graph showing change in resonant frequency
20-Graph showing the energy conversion degree according to the frequency band of the cantilever type vibration energy converter according to the prior art
21 is a graph showing the energy conversion degree according to the frequency band of the first cantilever beam of the vibration energy conversion device according to an embodiment of the present invention.

The present invention relates to a vibration energy conversion device for harvesting energy in a time-varying frequency environment in which the external vibration frequency is variously changed and varied, and does not depend on a separate physical, electrical or electronic control element, and inherently changes according to the external vibration frequency change. The present invention relates to a vibration energy conversion device capable of changing the frequency (resonance frequency) by itself and realizing more improved energy conversion efficiency and a method of manufacturing the same.

Vibration energy conversion device according to an embodiment of the present invention, the free end is repeatedly bent and deformed and vibrated under the influence of external vibration, and the charge is polarized in response to the internal stress caused by the bending deformation to generate a voltage (electric It consists of a piezoelectric element that can be converted into energy, and uses a cantilever whose natural frequency (resonant frequency) changes with its length.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are conceptual views illustrating a first operating state and a second operating state of a vibration energy converter capable of self-adjusting a resonant frequency according to a first embodiment of the present invention, respectively. Main part longitudinal section view.

In the vibration energy converter according to the first embodiment of the present invention, the cantilever vibrating body (100) having the first and second cantilever beams (110, 120) of different lengths with free ends facing in opposite directions, and the cantilever beam It consists of a cantilever fixture (200) for guiding the vibrating body (100) to be movable in a horizontal direction.

The cantilever vibrating body 100 connects the fixed ends of the first and second cantilever beams 110 and 120 to the first and second cantilever beams 110 and 120, and the first and second cantilever beams 110. , 120 is made of a cantilever interpolation connecting portion 130 having a continuous outer surface that is slidable in one direction corresponding to the longitudinal direction of.

The cantilever vibrating body 100 is composed of a piezoelectric element including a piezoelectric polymer having a Young's modulus (flexibility, elasticity) of several GPa or less, such as polyvinylidene fluoride (PVDF), or the cantilever with other flexible materials. After fabricating the cantilever structure corresponding to the skeleton of the vibrating body 100, the piezoelectric polymer may be bonded to a part or the whole thereof, thereby giving energy harvesting characteristics for converting vibration energy into electrical energy.

The first and second cantilever beams 110 and 120 may be provided one by one, but as shown in the first embodiment of the present invention, a plurality of the first cantilever beams 110C are formed in succession and the first cantilever group 110C is formed. In addition, a plurality of second cantilever 120 may be formed in succession to form a second cantilever group 120C.

When the first and second cantilever groups 110C and 120C are provided, the energy harvesting efficiency can be further improved by expanding the polarization area capable of energy harvesting, as compared with the case where the first and second cantilever groups 110 and 120C are provided one by one. While flexible, it is possible to implement the same degree of flexibility as one of the first and second cantilever beams 110 and 120 compared to a large area integrated structure.

On one or both surfaces of the first cantilever 110 and the second cantilever 120 that are bent and vibrated under the influence of external vibration, polarization is performed at the first and second cantilever 110 and 120. The electrodes 140 forming the movement path of the charge are combined.

The electrode 140 may increase the harvesting efficiency of the electrical energy generated by the first and second cantilever 110 and 120 in proportion to the bonding area on the first and second cantilever 110 and 120, and platinum Conductive materials such as, gold, silver, copper, chromium, nickel, aluminum, ITO, IGO, AGO, or sulfur compounds may be applied.

When bonding the conductive material of the electrode 140 to the surface of the first, second cantilever (110, 120), if not formed in the form of a solid structure in the form of a screen (paste) screen print (screen print) method The continuous charge transfer path can be clearly formed without inhibiting the flexible deformation of the first and second cantilever 110 and 120.

Proof mass 150 is coupled to the free ends of the first and second cantilever 120, and the proof mass 150 is in addition to its own mass at the free ends of the first and second cantilever 120. In order to make the inertial force work more clearly by giving a mass, the first and second cantilever 120 may be combined with the same mass (for example, 0.1 g) or may be combined with different masses. .

The cantilever fixture 200 has a contact surface that can restrain the bending deformation of the first and second cantilever beams 110 and 120, and is coupled to the cantilever interpolation connecting portion 130 of the cantilever vibration body. In the example has a structure consisting of a guide portion 210 is coupled to one side of the cantilever interlocking portion 130 and a fixing portion 220 is coupled to the other side.

The guide portion 210 is formed with a guide groove 211 for reciprocating the cantilever interlocking portion 130 of the cantilever vibrating body in the longitudinal direction of the first, second cantilever (110, 120).

The fixing part 220 is coupled to the guide part 210 with the cantilever vibrating body 100 interposed therebetween, with the guide groove 211 of the guide part being coupled to the guide part 210. The slit-shaped space portion and the contact surface which can restrain the vertical bending deformation of the cantilever vibrating body 100 are formed.

By the above configuration, the first and second cantilever beams 110 and 120 of the cantilever vibrating body have a free end portion in a horizontal direction based on both ends of the cantilever fixing body 200 (FIGS. 1, 2 and 3 in left and right directions). It has a protruding shape, and both ends of the cantilever fixture 200 is constrained the bending deformation of the first, second cantilever (110, 120), of the first, second cantilever (110, 120) The fixed end is a point corresponding to both ends of the cantilever fixture (200).

As described above, the cantilever vibrating body 100 has a fixed end side portion of the first and second cantilever beams 110 and 120 according to a relative position on the cantilever fixing body 200 on the cantilever fixing body 200. The lengths of the first and second cantilever beams 110 and 120 that are selectively restrained and protrude out of the cantilever fixture 200 are determined.

The free ends of the first and second cantilever beams 110 and 120 exposed to the outside of the cantilever fixture 200 are vertical in the vertical direction due to the flat longitudinal section shape and the flexibility of the material of the cantilever fixture 200. , Up and down direction of 3) can be bent deformation, and the vibration or resonance in the form as described above by the external vibration.

Since the first and second cantilever beams 110 and 120 have different natural frequencies (resonant frequencies) according to differences in their lengths, the first and second cantilever beams 110 and 120 have different natural frequencies (resonant frequencies). The shapes are different from each other, and thus the forces acting in the horizontal direction on the first and second cantilever beams 110 and 120 are also different from each other.

FIG. 13 is a conceptual diagram illustrating movement trajectories, horizontal and vertical displacements of end portions of the first and second cantilever beams 110 and 120 according to the bending deformation of the first and second cantilever beams 110 and 120, and FIG. 14 illustrates vibrations of the first and second cantilever beams 110 and 120. This is a conceptual diagram showing the inertial force acting upon.

Referring to FIGS. 13 and 14, the first and second cantilever beams 110 and 120 have a circular trajectory at a predetermined distance with respect to the fixed end when the vibration is performed as described above. Centrifugal force (inertial force generated during acceleration motion (for example, circular motion)) (F ₁ , F _{2 in} FIG. 14) is applied to each of the 1 and 2 cantilever beams 110 and 120.

When the horizontal centrifugal force acting on the first cantilever 110 side among the horizontal centrifugal forces (F _x1 , F _{x2 in} FIG. 14) acting on the first and second cantilever 110 and 120 is relatively large, FIG. 1, the first operating state (phase 1) as shown in (a) of FIG. 3 is maintained or switched to the first operating state side, the horizontal centrifugal force acting on the second cantilever 120 side is relatively If large, the second operation state (phase 2) as shown in Figs. 2 and 3 (b) is maintained or is switched to the second operation state side.

In the first operating state illustrated in FIGS. 1 and 3A, the cantilever vibrator 100 moves to one side of the cantilever fixture 200 such that the first cantilever 110 has the longest length. 2 and 3 (b), the cantilever vibrating body 100 is the cantilever fixture 200 so that the second cantilever 120 has the longest length. It is moved to the other side of.

In the first operating state, when the horizontal inertial force acting on the second cantilever 120 is greater than the horizontal inertial force acting on the first cantilever 110 by the change of the external vibration frequency, the first, The cantilever interlocking portion 130 is automatically slid on the cantilever fixing body 200 by the inertia force difference between the two cantilever beams 110 and 120, and the phase of the cantilever vibrating body 100 changes to the second operating state side. Done.

On the contrary, when the horizontal inertial force acting on the first cantilever 110 becomes larger than the horizontal inertial force acting on the second cantilever 120 by the change of the external vibration frequency in the second operating state, The cantilever interlocking portion 130 is automatically slid on the cantilever fixture 200 by the inertia force difference between the 1 and 2 cantilever beams 110 and 120, and the phase of the cantilever vibrating body 100 is in the first operating state. Will change to the side.

In the first embodiment of the present invention on the cantilever interlocking connection 130 of the cantilever vibrating body slit 131 is the longitudinal direction of the first and second cantilever beams 110 and 120 (left and right directions in Figs. 1, 2 and 3 phases). And a bump 212 protruding from the slit 131 to form a horizontal movement limit of the slit 131 on the guide groove 211 of the cantilever fixture.

Accordingly, the horizontal width difference between the slit 131 and the bump 212 determines the maximum displacement of the cantilever vibrating body 100, and the relative forming position of the slit 131 or the bump 212 is determined. The lengths of the first and second cantilever beams 110 and 120 in the first and second operating states are determined.

In addition, a plurality of ribs 132 may be formed on the side portions of the cantilever interlocking portions 130 of the cantilever vibrating body in a right angle direction (a horizontal direction perpendicular to the longitudinal direction of the first and second cantilever beams). The extension guide groove 213 is formed to protrude in a direction perpendicular to the longitudinal direction of the cantilever (110, 120), the horizontal guide groove 213 on the cantilever fixture 200 to form a horizontal movement limit of the rib (132) 132 is formed in a designated width at a position corresponding to 132.

Like the case of the slit 131 and the bump 212, the rib 132 and the extension guide groove 213, the width difference in the horizontal direction (the longitudinal direction of the first and second cantilever beams) is the cantilever vibrating body Determine the maximum displacement of the movement of the (100), the relative forming position of the rib 132 and the extension guide groove 213 is the first, second cantilever 110, in the first and second operating state 120) to determine the length.

The slits 131 and the bumps 212, the plurality of ribs 132, and the extension guide grooves 213 may be formed in the middle of the cantilevered oscillator and the interpolated connecting part 130 of the cantilever oscillator, respectively, in a right and left direction. In order to stably guide the sliding movement in the horizontal direction (the longitudinal directions of the first and second cantilever beams 110 and 120) within a predetermined displacement of the cantilever vibrating body 100 at a plurality of places corresponding to the front and rear sides in the longitudinal direction. do.

The cantilever vibrating body 100 is automatically moved on the cantilever fixture 200 according to the change of the external vibration frequency as described above, and according to the sliding movement position on the cantilever fixture 200. The positions of the fixed ends of the cantilever beams 110 and 120 are changed, and at the same time, the lengths and natural frequencies of the first and second cantilever beams 110 and 120 are also changed in real time.

Next, a manufacturing method of the vibration energy converter according to the first embodiment of the present invention having the above configuration will be described.

(A), (b), 4b, 4c of Figure 4a is a conceptual diagram showing the manufacturing process of the cantilever vibrating body 100, Figure 5a, (b), (c) is the cantilever fixture FIG. 6 is a conceptual diagram illustrating a manufacturing process of the 200, and FIG. 6 is an exploded perspective view illustrating a process of assembling the cantilever vibrating body 100 to the cantilever fixing body 200.

In the vibration energy conversion device according to the first embodiment of the present invention, the structure forming step, the electrode forming step, the mass coupling step and the cantilever vibrating body 100, which is a process of manufacturing the cantilever vibrating body 100, The cantilever fixture 200 may be manufactured through a fixture coupling step of coupling with the fixture.

Referring to FIG. 4A, in the structure forming step, a film-type piezoelectric element having flexibility such as PVDF (polyvinylidene fluoride) (eg, thickness: 110 μm, 0.5 mm or less, etc.) (not shown) is lasered. The cantilever structure 100a having a shape having the first and second cantilever beams 110 and 120 having different lengths having free ends facing in the opposite direction is manufactured by patterning the same.

Referring to FIG. 4B, in the electrode forming step, a paste made of a conductive material may be formed on the surface of one or both of the first cantilever 110 and the second cantilever 120 of the cantilever structure 100a by a screen printing process. The electrode 140 is formed by continuously coating the cantilever interpolation connector 130.

In the first embodiment of the present invention, the electrode 140 formed on the cantilever interpolation connecting portion 130 has a structure formed up to a part of the plurality of ribs 132 that is not adjacent to the slit 131, If the electrical connection path between the first and second cantilever (110, 120) and the external device is formed is not limited to a specific structure and shape.

The electrode 140 is connected to an electronic circuit (not shown) for energy recovery using a lead wire, and is polarized at one or both sides of the first cantilever 110 and the second cantilever 120 of the cantilever structure 100a. Charge (converted electrical energy) is transferred to the electronic circuit side through the cantilever interpolation connector 130.

Referring to FIG. 4C, in the mass coupling step, the proof mass 150 is coupled to the free ends of the first and second cantilever beams 110 and 120 having a vertical vibration displacement among the cantilever structures 100a. The inertial force acting by the masses of the first and second cantilever beams 110 and 120 and the additional mass by the proof mass 150 clearly and stably induces the vertical vibration of the cantilever vibration body 100. .

Referring to FIG. 5, the cantilever fixture 200 has a photoresist coating step, an exposure step, a developing step, and a curing process using an acrylic resin having excellent formability, processability, hardness, and surface gloss, such as polymethly methacrylate (PMMA). It can be produced through the step, insulating film separation step.

In the photoresist coating step, a photoresist (for example, as shown in FIG. 5B) is formed on a plate-shaped PMMA structure (not shown) as shown in FIG. 5A. A meltable material is coated on an etchant such as a negative photoresist such as SU-8 and SU-8.

In the exposing step, a photomask having a channel corresponding to the guide grooves 211, the bumps 212, and the extension guide grooves 213 is disposed above the photosensitive material to expose the photosensitive material. By immersing the PMMA structure in a developer solution to remove the unexposed portion of the photosensitive material, as shown in (c) of FIG. 5, the guide grooves 211, bumps 212, extension guides on the surface of the PMMA structure. A groove portion having a shape corresponding to the groove 213 is formed.

Referring to FIG. 6, in the fixing unit coupling step, the cantilever interlocking unit 130 of the cantilever vibrating body is interposed therebetween, and the guide unit 210 and the fixing unit 220 of the cantilever fixing unit are coupled to each other.

In the first embodiment of the present invention, the fixing portion 220 has a flat plate-like surface in contact with the guide portion 210, the contact between the guide portion 210 and the fixing portion 220 of the cantilever fixture In addition, the guide grooves 211, bumps 212, and extension guide grooves 213 may be made at portions corresponding to the upper surface of the state shown in FIG.

The guide part 210 and the fixing part 220 of the cantilever vibrating body 100 are positioned inside the guide groove 211 of the guide part in a state where the cantilever vibrating body 100 is interposed therebetween. The slit-shaped space portion can be formed to constrain the bending deformation.

In forming the slit-shaped space portion on the cantilever fixture 200, the guide groove 211 may be formed on both the guide portion 210 and the fixing portion 220, but the guide portion 210 and When the guide groove 211 is formed on only one side of the fixing part 220, the process shown in FIG. 5 may be more simply manufactured by applying the process as shown in FIG. 5 only to the guide part 210.

7 is a photograph of the vibration energy conversion device actually manufactured according to the embodiment of the present invention as described above, Figure 8 is the second operation in the first operating state during the frequency conversion characteristics of the vibration energy conversion device actually manufactured It is a photograph taken by enlarging the rib 132 in the state switched to the state.

9 is an enlarged photograph of the rib 132 in a state in which the second operating state is switched to the first operating state. FIGS. 10, 11, and 12 show that the first cantilever 110 equilibrates with each other. It is the photograph which photographed the state which achieves, the state which bends down maximum, and the state which bends up maximum.

Referring to FIG. 7, the cantilever fixture 200 may be formed of a transparent PMMA material, and a groove part including the guide groove 211, the bump 212, and the extension guide groove 213 may be manufactured from a SU-8 material. 6, a portion of the plurality of ribs 132 formed in the electrode 140 (white) is exposed to the outside of the cantilever fixture 200.

As described above, the electrode 140 may be exposed to the outside of the cantilever fixture 200 to easily connect with an external electronic circuit (not shown) using a lead wire or the like.

In forming the first cantilever beam 110 and the second cantilever beam to have different lengths, the length of the first cantilever beam elastically deformed by the horizontal movement of the cantilever vibration body 100. The shortest length is formed to have a length longer than the longest length of the second cantilever 120 (for example, the length range of 12 ~ 14mm of the first cantilever 110, the length of the second cantilever 120 Range 9.5 ~ 11.5mm).

8 and 9, the ribs 132 are located on one side on the extension guide groove 213 in the first operating state, and on the other side on the extension guide groove 213 in the second operating state. We can see that we are located biasedly.

In forming the rib 132, as shown in Figs. 8 and 9, it is convex toward the reciprocating movement path side of the rib 132 between the position in the first operating state and the position in the second operating state. When the uneven portion (not shown) of the protruding shape is formed, the rib 132 is difficult to be stably positioned over the foreground path from the first operating state to the second operating state by the uneven portion. Only the first operation state or the second operation state is selectively implemented.

10, 11, and 12, when the distance from the fixed end to the free end of the first cantilever 110 has a length of 14mm, the distance is 13.1mm, even in the maximum downward and upward bending state, respectively It can be seen that there is a slight difference of less than 1mm as 13.6mm, according to this, it can be approximated that the free end forms a circular trajectory at a certain distance with respect to the fixed end during the vibration of the first cantilever 110. Can be.

Referring to FIGS. 13 and 14, when the horizontal and vertical components of the first and second cantilever beams 110 and 120 are vibrated by the application of external vibration in detail, the first and second cantilever beams 110 and 120 may be analyzed. The free end has a horizontal displacement Δ and a vertical displacement δ _B by the application of external vibration F ₀ sin (2πft), so that the largest bending moment acts on the fixed ends A of the first and second cantilever beams 110 and 120. do.

The free ends B of the first and second cantilever beams 110 and 120 move in the shape of an actual elliptic trajectory, but the modified length AB is close enough to ignore the difference compared to the length L of the cantilever beam before deformation. It may be assumed that the deflection curves of the free end trajectories of the first and second cantilever 110 and 120 form a circular arc.

The horizontal (x-axis) displacement Δ,

가 되며,

Respectively,

The vertical (y-axis) displacement δ _B is

는 상기 제1, 2외팔보(110, 120)의 감쇠비(damping ratio)이고, k는 스프링 상수이며, f_n은 공진주파수이다.remind

Is a damping ratio of the first and second cantilever 110 and 120, k is a spring constant, and f _n is a resonance frequency.

In addition, the linear velocity v of the free ends of the first and second cantilever (110, 120),

The mass m ₁ and m ₂ of the proof mass 150 coupled to the free ends of the first and second cantilever 110, 120 receive centrifugal forces F ₁ and F ₂ , respectively, and the cantilever vibrating body 100 has a centrifugal force. The horizontal movement is possible according to the difference between the horizontal components F _x1 and F _x2 of F ₁ and F ₂ .

), 상기 제1, 2외팔보(110, 120) 자유단의 수직변위 δ_B가 일반적인 스프링-질량-댐퍼(spring-mass-damper) 시스템을 따른다고 가정하면, 수평 관성력 F_x1, F_x2는,In order to obtain F _x1 and F _x2 according to the external vibration frequency f, deformation of the first and second cantilever beams 110 and 120 mainly occurs at the fixed end A of the first and second cantilever beams 110 and 120 (

), Assuming that the vertical displacement δ _B of the free ends of the first and second cantilever beams 110 and 120 follows a general spring-mass-damper system, horizontal inertia forces F _x1 and F _x2 are

It can be approximated by using.

Based on the above formulas, the vibration energy converter according to the embodiment of the present invention can be designed to have a resonant frequency band in a specified range without repeatedly undergoing a cumbersome process of making, experimenting and modifying a plurality of prototypes. Can be.

FIG. 15 is a photograph of an experimental apparatus for resonant frequency variation characteristics of a vibration energy converter according to an exemplary embodiment of the present invention, and FIG. 16 is a schematic diagram of FIG. 15.

Referring to FIGS. 15 and 16, the external vibration frequency is increased or changed through a setup such as a function generator, a vibration source, an excitor, a load resistance, an oscilloscope, and the like. The characteristics of the vibration energy converter according to the present invention were tested.

The cantilever vibrating body 100 actually manufactured according to an embodiment of the present invention has the shortest length among the length ranges of the first cantilever 110 that is elastically deformed by horizontal movement. It was formed to have a length longer than the length.

That is, [the length L ₁ of the first cantilever 110 in the first operating state> the length L ₁ ′ of the first cantilever 110 in the second operating state> the length of the first cantilever 110 in the second operating state. The length L ₂ ′ of the second cantilever 120 is manufactured such that the length L ₂ of the second cantilever 120 in the first operating state is described below. FIGS. 17 to 21 show the external vibration frequency bands according to the structure. The results of the experiment are summarized.

17 and 18 are graphs showing horizontal inertia forces acting on the first and second cantilever beams 110 and 120 according to frequency bands in the first and second operating states, respectively.

Referring to FIG. 17, the resonant frequencies f ₁ and f ₂ of the first and second cantilever 110 and 120 in the first operating state are f ₁ <f ₂ , and the external vibration is performed in the first operating state. When the frequency f is gradually increased from a frequency band lower than f ₁ to a frequency band higher than f ₂ , the horizontal inertia force F _x1 of the first cantilever 110 becomes maximum in the frequency band corresponding to f ₁ , and f _In the frequency band corresponding to ₂ , the horizontal inertial force F _x2 of the second cantilever 120 becomes maximum.

As the external vibration frequency f gradually increases and approaches f ₂ , the amplitude of the first cantilever 110 (horizontal inertia force F _x1 ) decreases, and the amplitude of the second cantilever 120 (horizontal inertia force F _x2 ). Since this increases, there is an external vibration frequency f _s (f ₁ <f _s <f ₂ ) in which F _x2 is larger than F _x1 .

The cantilever vibrating body 100 moves horizontally in the direction F _x2 at an external vibration frequency f _s , and its phase is changed from the first operating state to the second operating state side. When the horizontal moving distance of the cantilever vibrating body 100 is d, the length of the first cantilever 110 is L ₁ -d, and the length of the second cantilever 120 is changed to L ₂ + d, Resonant frequencies of the first and second cantilever 110 and 120 are tuned to f ₁ ′ and f ₂ ′, respectively.

Referring to FIG. 18, the resonant frequencies f ₁ ′ and f ₂ ′ of the first and second cantilever 110 and 120 in the second operation state are compared with the graph of FIG. 17, and f ₁ <f ₁ ′. <f ₂ '<f ₂ , and in the second operating state, when the external vibration frequency f ′ is gradually reduced from the frequency band higher than f ₂ to the frequency band lower than f ₁ , the frequency band corresponding to f ₂ ′. In the past, the horizontal inertial force F _x2 ′ of the second cantilever 120 becomes maximum, and the horizontal inertial force F _x1 of the first cantilever 110 becomes maximum in the frequency band corresponding to f ₁ .

As the external vibration frequency f gradually decreases and approaches f ₁ , the amplitude (horizontal inertial force F _x2 ) of the second cantilever 120 decreases, and the amplitude (horizontal inertial force F _x1 ) of the first cantilever 110 increases. Therefore, there is an external vibration frequency f _s '(f ₁ '<f _s '<f ₂ ') in which F _x1 is larger than F _x2 .

17 and 18, f ₁ and f ₂ in the first operating state are 24 Hz and 40 Hz, respectively, and the boundary frequency f _s changed to the second operating state is 35 Hz, and f ₁ in the second operating state. ', f ₂ ' were 32 Hz and 34 Hz, respectively, and the boundary frequency f _s ' changed to the first operating state was 33 Hz.

The resonant frequency of the first cantilever 110 in the first operating state is real-time self-tuning from 24 Hz to 32 Hz, and the resonant frequency of the second cantilever 120 in the second operating state is real-time self tuning from 34 Hz to 40 Hz It became.

When the external vibration frequency mainly has a fluctuation band in the range of 24 Hz to 32 Hz, energy harvest using the first cantilever 110 is mainly set, and as shown in FIG. By forming only on the side of the cantilever 110, energy harvesting can be realized in a wider (multiple) frequency band target not only in a specific frequency band such as 24 Hz or 32 Hz, but also in a 24 Hz to 32 Hz frequency band.

The tuning range of the first and second cantilever 110 and 120 may be designed according to a moving distance between the first and second operating states (for example, 5 Hz-> d = 2 mm).

19 is the first operation state in which the external vibration frequency is increased to the second operation state in the first operation state, and the external vibration frequency is reduced in the second operation state and the second operation state is switched back to the first operation state. 1 is a graph showing the change in the resonant frequency with time of the cantilever 110.

The left vertical axis, the right vertical axis, and the horizontal axis of the graph shown in FIG. 19 represent the resonant frequency, the external vibration frequency, and the time of the first cantilever 110, respectively. The external vibration frequency range starts from the first operating state. Was increased from 10 Hz or less to 40 Hz or more and again decreased to 10 Hz or less, and the resonance frequency of the first cantilever 110 was continuously measured.

Referring to FIG. 19, as the external vibration frequency increases from 10 Hz to 40 Hz and then decreases again, the operating state of the cantilever vibrating body 100 changes from the first operating state to the second operating state in a few seconds (externally). It can be seen that the vibration frequency is changed in real time from the second operating state back to the first operating state (at the external vibration frequency 33 Hz) at 35 Hz).

In the first operation, the resonant frequency of the first cantilever 110 was 24 Hz, and the resonant frequency of the first cantilever 110 changed to 32 Hz while changing to the second operating state, and returned to the first operating state. While changing, the resonant frequency of the first cantilever 110 was changed back to 24 Hz.

20 is a graph showing the energy conversion degree according to the frequency band of the cantilever type vibration energy conversion device according to the prior art, Figure 21 is a graph showing the energy conversion degree according to the frequency band of the first cantilever 110.

Referring to FIGS. 20 and 21, a general cantilever energy harvesting device that does not implement self tuning has only one output peak at 24 Hz, but performs self tuning as in the embodiment of the present invention. In the implementation, we can see that the output peak is in two regions corresponding to 24Hz and 32Hz.

20 and 21, the vibration energy converter according to the embodiment of the present invention is not limited to a specific frequency band, but energy in a wider (multiple) frequency band object covering a frequency band from 24 Hz to 32 Hz. You can see that the harvest can be implemented.

On the perpendicular end of the continuous guide groove 213 in the first embodiment of the present invention, as shown in Figs. 8 and 9, the position and the second operation of the rib 132 in the first operating state It has a structure in which one uneven part (not shown) of the shape which protrudes convexly toward the reciprocation movement path side of the said rib 132 is formed between the positions in the state.

Forming a plurality of uneven portions between the position in the first operating state and the second operating state of the rib 132 allows the rib 132 to be selectively positioned between the plurality of uneven portions. In addition, the movement of the cantilever vibrating body 100 may be stabilized at a more various position (operation state) corresponding to the position in the first operation state and the position in the second operation state.

Through various experiments as shown in FIGS. 17 to 21, the cantilever vibrating body 100 according to the embodiment of the present invention having an asymmetrical and horizontally movable structure has an external vibration frequency without an additional energy source for changing the resonance frequency. It was confirmed that the self-tuning (tuning) in real time while automatically moving in conjunction with the change of (the length of the first, second cantilever (110, 120) changes).

The present invention has been described with reference to preferred embodiments of the present invention, but the present invention is not limited to these embodiments, and the claims and detailed description of the present invention together with the embodiments in which the above embodiments are simply combined with existing known technologies. In the present invention, it can be seen that the technology that can be modified and used by those skilled in the art are naturally included in the technical scope of the present invention.

100: cantilever vibrating body 100a: cantilever structure
110: first cantilever 110C: first cantilever
120: second cantilever 120C: second cantilever
130: cantilever interpolation connection 131: slit
132: rib 140: electrode
150: proof mass 200: cantilever fixture
210: guide portion 211: guide groove
212: bump 213: extension guide groove
220: fixed part

Claims (16)

In the vibration energy converter using the cantilever beam,
A cantilever vibrating body (100) having first and second cantilever beams (110, 120) of different lengths having free ends facing in opposite directions; And
It has a contact surface that can restrain the bending deformation of the first and second cantilever (110, 120) is coupled to the cantilever interpolation connecting portion 130 of the cantilever vibrating body, the cantilever vibrating body 100 is movable in a horizontal direction Guide cantilever fixture 200;
Vibration energy converter capable of self-adjustment of the resonance frequency comprising a.
The method of claim 1,
The cantilever vibrating body 100,
Vibration energy conversion device capable of self-adjustment of the resonant frequency, characterized in that it comprises a piezoelectric polymer such as PVDF (Polyvinylidene fluoride).
The method of claim 1,
The cantilever vibrating body 100,
A first cantilever group (110C) formed by continuously arranging a plurality of the first cantilever beams (110); And
A second cantilever group (120C) formed by continuously arranging a plurality of the second cantilever beams (120);
Vibration energy converter capable of self-adjustment of the resonance frequency comprising a.
The method of claim 1,
The cantilever vibrating body 100,
The first and second cantilever (110, 120) is composed of a conductive material that can form a movement path of the polarized (polarized) charge on the surface of one or both of the first cantilever 110 and the second cantilever 120 An electrode 140 coupled;
Vibration energy converter capable of self-adjustment of the resonance frequency further comprising.
The method of claim 1,
The cantilever vibrating body 100,
A proof mass 150 coupled to the free ends of the first cantilever 110 and the second cantilever 120;
Vibration energy converter capable of self-adjustment of the resonance frequency further comprising a.
The method of claim 1,
The cantilever vibrating body 100,
Vibration energy conversion device capable of self-adjustment of the resonant frequency, characterized in that the part of the fixed end side of the first, second cantilever (110, 120) is selectively restrained in accordance with the relative position on the cantilever fixture (200).
The method of claim 1,
The cantilever fixture 200,
A guide part 210 having a guide groove 211 for reciprocating the cantilever interlocking part 130 of the cantilever vibrating body in a longitudinal direction of the first and second cantilever beams 110 and 120; And
The slit-shaped space portion coupled to the guide portion 210 with the cantilever vibrating body 100 interposed therebetween and capable of restraining vertical bending deformation of the cantilever vibrating body 100 together with the guide groove 211 of the guide portion. And a fixing part 220 forming a contact surface.
Vibration energy converter capable of self-adjustment of the resonance frequency comprising a.
The method of claim 7, wherein
A slit 131 extending in the longitudinal direction of the first and second cantilever beams 110 and 120 on the cantilever interpolation portion 130 of the cantilever vibration body; And
A bump 212 protruding from the guide groove 211 to penetrate the slit 131 to form a horizontal movement limit of the slit 131;
Vibration energy converter capable of self-adjustment of the resonance frequency further comprising a.
9. The method according to claim 7 or 8,
Ribs 132 protruding on the cantilever interlocking portion 130 of the cantilever vibrating body in a direction perpendicular to the longitudinal direction of the first and second cantilever beams 110 and 120; And
An extension guide groove 213 formed at a position corresponding to the rib 132 on the cantilever fixture 200 to define a horizontal movement limit of the rib 132;
Vibration energy converter capable of self-adjustment of the resonance frequency further comprising.
The method of claim 1,
The first cantilever 110,
Vibration energy conversion device capable of self-adjustment of the resonant frequency, characterized in that the shortest length of the length range that is stretched and deformed by the horizontal movement of the cantilever vibrating body 100 is longer than the longest length of the second cantilever 120. .
The method of claim 1,
A first operating state in which the cantilever vibrating body 100 is moved to one side of the cantilever fixing body 200 such that the first cantilever 110 has the longest length; And
A second operating state in which the cantilever vibrating body 100 is moved to the other side of the cantilever fixing body 200 so that the second cantilever 120 has the longest length;
Vibration energy converter capable of self-adjustment of the resonant frequency having a.
In the vibration energy converter using the cantilever beam,
The cantilever beams 110 and 120 of different lengths are connected to each other so that the free ends face in opposite directions, and are automatically slid by a difference in inertia force between the cantilever beams 110 and 120 according to a change in an external vibration frequency. Cantilever vibrating body 100 to be changed;
Vibration energy converter capable of self-adjustment of the resonance frequency comprising a.
The method of claim 12,
The cantilever vibrating body 100,
The position of the fixed ends of the cantilever beams 110 and 120 varies according to the sliding movement position, and the vibration energy converter capable of self-adjusting the resonant frequency, characterized in that the length and the natural frequency of the cantilever beams 110 and 120 are changed. .
In the cantilever vibrating body 100 of the vibration energy converter using the cantilever,
First cantilever 110;
A second cantilever 120 having a length different from that of the first cantilever 110 and having a free end facing in a direction opposite to the first cantilever 110; And
A cantilever interlocking portion 130 which interconnects the fixed ends of the first cantilever 110 and the second cantilever 120 and has a continuous outer surface slidable in one direction;
Cantilever vibrating body 100 of the vibration energy converter comprising a.
In the manufacturing method of the vibration energy converter using the cantilever beam,
A structure forming step of fabricating a cantilever structure 100a having a first and second cantilever beams 110 and 120 having different lengths having free ends facing in opposite directions by patterning a film type piezoelectric element;
An electrode forming step of forming an electrode 140 by coating a conductive material on a surface of one or both sides of the first cantilever 110 and the second cantilever 120 of the cantilever structure 100a;
A mass coupling step of coupling a proof mass 150 to an end of the cantilever structure 100a to complete a frame of the cantilever vibrating body 100; And
After the mass coupling step, the cantilever interpolation connecting portion 130 of the cantilever vibrating body is provided with a guide groove 211 for guiding the bending deformation of the first and second cantilever beams 110 and 120 in a horizontal direction with a restrainable contact surface. Fixture coupling step of coupling on the cantilever fixture 200;
Vibration energy conversion device manufacturing method comprising a. delete

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