JP2011193665A - Power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact power generation system which efficiently converts kinetic energy such as vibration into electric energy to generate power, without enforcing a user to operate for power generation. <P>SOLUTION: The power generation system includes: a power generation film 14 constituted of a ferroelectric thin film 12 which is curved by kinetic energy and a first electrode 16 and a second electrode 17 formed respectively on the front and rear surfaces of the thin film 12; a rectifying circuit 20 for converting the voltage generated at the first electrode 16 and the second electrode 17 by the curved thin film 12 into direct current; a voltage converter 24 for converting the converted direct voltage into a predetermined voltage; and a power storage means 26 for storing the converted electric charge. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power generation system that converts kinetic energy such as sound and vibration into electrical energy.

In recent years, as one of the measures to reduce CO ₂ emissions that are a cause of global warming, energy harvesting that converts sunlight, geothermal, wind power, tides, etc. into electrical energy Is attracting attention.

  These power generation methods are still more expensive than oil-based power generation and nuclear power generation, which are widely used at present, but they are superior in terms of safety and cleanliness and will be actively introduced in the future. It is expected that.

On the other hand, when installing measuring instruments equipped with artificial intelligence and communication functions, the generation and storage of electrical energy represented by smart grids, etc., which have the function of automatically adjusting the power supply and demand for these devices. Other networks are also being considered. If power consumption control and efficient use are established throughout the society like this smart grid, it will be easy to introduce new systems such as electric vehicles, further reducing CO ₂ emissions, and reducing environmental impact. A transition to a friendly society can be expected.

  In response to the supply and demand of relatively large-scale power as described above, in portable devices and the like, after improving the performance, size, thickness, and weight of portable devices so that users can easily use them, Ensuring power supply such as reducing charging frequency is required. In recent years, as the performance of portable devices has increased, their applications have been expanded and the usage time has been extended for a long time, and the required power demand has been increasing. However, the capacity of batteries such as lithium ions used as power sources for portable devices has hardly increased, and expectations for power supply in a ubiquitous environment are very high.

  Regarding power supply in a ubiquitous environment, Patent Document 1 proposes an invention for extracting power from mechanical vibration energy. In the piezoelectric power generation mechanism proposed in Patent Document 1, a vibrator that forms an unbalanced mass moment near the center of a rod-shaped spring material held at both ends, a piezoelectric element that generates power by deformation, and Is arranged. The piezoelectric element generates power of 0.1 to 0.6 μW when receiving vibration from the outside and exciting the torsional vibration of the spring material by the mass of the vibrator.

  When the piezoelectric power generation mechanism proposed in Patent Document 1 is installed in a building such as a building or a bridge, when the building vibrates at a low frequency due to the passage of a wind or a surrounding moving body, The piezoelectric power generation mechanism can generate electric power. In Patent Document 1, it is possible to monitor the stress applied to a building, etc. over a long period of time by using the generated electric power for a power source for an acceleration sensor or a strain sensor attached to the building. It is possible to predict possible damage.

  In addition, Patent Literature 2 proposes a piezoelectric vibration generator that can be used as a power source for a sensor network terminal having both a sensing function and a wireless communication function. In the piezoelectric vibration generator proposed in Patent Document 2, a power generation film with electrodes formed on the front and back surfaces is attached to a rectangular base film that can be bent and deformed, and one end of the power generation film is fixed with a support pillar. A cantilever structure with the end as a free end is provided with a weight for increasing the amplitude at the tip of the free end.

  By using the piezoelectric vibration generator proposed in Patent Document 2, the amount of power generation can be increased while reducing the size and the bottom area. By using the piezoelectric vibration generator as a power source for a sensor network terminal that detects temperature, humidity, acceleration, etc., and transmits it by wireless communication, battery replacement is unnecessary, and a long-life sensor network in various places and living organisms The terminal can be attached.

  Patent Document 3 proposes a portable generator driven by human power. The portable generator proposed in Patent Document 3 includes a bimorph formed by attaching a piezoelectric element to a rectangular elastic plate supported at both ends in a case, and the bimorph center is bent by a user applying an external force. And a pressurizing mechanism for generating the pressure.

  When the connector of the portable generator proposed in Patent Document 3 is connected to a portable device and the user repeatedly presses the pressing mechanism, the bimorph in the case is repeatedly bent by the pressing force of the pressing mechanism. An alternating electric field is generated by the piezoelectric positive effect on the electrode of the piezoelectric element attached to the electrode, and (+) (−) charges are generated on the electrode of the piezoelectric element. This is converted into direct current through rectifying diodes as electric energy and transmitted to the portable device via the connector, whereby the secondary battery of the portable device can be charged.

WO2008 / 053835 JP 2009-247128 A JP 2004-282978 A

  The natural frequency of the piezoelectric power generation mechanism described in Patent Document 1 has a relatively high natural frequency of about 6 to 10 Hz. Therefore, it seems convenient to generate electricity by attaching it to a building or bridge, but it is difficult to obtain resonance at a frequency of 6 to 10 Hz even when used for a terminal carried by a person. In addition, since the arranged piezoelectric element is as small as about 0.1 mm, there is a problem that power to be generated is small. Similarly, the piezoelectric vibration generator described in Patent Document 2 also has a problem that it is difficult to resonate at a low natural frequency.

  In the portable generator described in Patent Document 3, it is necessary for the user to continue to apply an external force to the pressurizing mechanism and to consciously “charge” during power generation.

  In addition, in photovoltaic power generation that is partly put into practical use, photoelectric conversion efficiency has increased in recent years, and there is a power generation efficiency of 30% or more. However, the difference between the power obtained from strong sunlight and the power obtained from a fluorescent lamp indoors is very large, and is not sufficient as a stable power supply source for portable devices. In addition, in power generation using solar cells, the installation angle with respect to the received light is also a major problem, and the efficiency is maximized when light is incident perpendicular to the solar cells, but the efficiency decreases as the tilt angle increases. Resulting in. Therefore, for example, if solar cells are installed on the dashboard of a car, etc., a large amount of power generation can be expected. It is difficult to ensure.

  In addition to solar power generation, power generation using a thermoelectric conversion element is also conceivable, but it is very difficult to ensure a temperature difference in the state that a person is carrying. On the other hand, as a device for converting a part of human kinetic energy into electric energy, there are a capacitor using a ceramic piezoelectric element or a highly charged material. Regarding the piezoelectric element, in addition to the generators described in the above-mentioned Patent Documents 1 to 3, for example, an element that is embedded in a road or stairs and generates power by using human treading force or driving vibration of a vehicle, A device using key input in a device or the like is known.

  In the case of a generator using these piezoelectric elements, there is a limit to reduction in thickness and flexibility because a ceramic ferroelectric is used. Therefore, it was not possible if the kinetic energy to be input was not large. In addition, in power generation using a capacitor using a highly charged material, there is a need to ensure a certain surface area and a need to maintain the electrode spacing as thin as possible. There is also a problem that the structure is limited, such as the need for a MEMS device (Micro Electro Mechanical Systems) integrated on the top.

  The present invention has been made in view of the above circumstances, and its purpose is to generate power by efficiently converting kinetic energy such as vibration into electric energy without forcing the user to perform power generation. An object of the present invention is to provide a small-sized power generation system that can be used.

  In order to solve the above problems, a power generation system according to the present invention includes a ferroelectric thin film that undergoes a bending motion upon receiving kinetic energy, and first and second electrodes formed on the front and back of the thin film. A power generation film, a rectifier circuit that converts the voltage generated in the first electrode and the second electrode by the bending motion of the thin film into DC, a voltage converter that converts the converted DC voltage into a predetermined voltage, and And a storage means for storing the charge after the voltage conversion.

  In the power generation system according to the present invention, the power generation film is configured to be formed into a bellows shape having a plurality of curved portions.

  In the power generation system according to the present invention, a part of the power generation film is configured to include a weight for increasing the amplitude of the bending motion.

  In the power generation system according to the present invention, the weight is configured to be attached to the first electrode or the second electrode in the power generation film.

  In the power generation system according to the present invention, the fixed end of the power generation film is configured to be fixed to an asymmetric rotating body having a mass moment unbalanced with respect to the rotation axis.

  The power generation system according to the present invention is a power generation system that converts kinetic energy into electrical energy, and is arranged on an asymmetric rotating body that performs oscillating motion in response to the kinetic energy, and the first electrode is formed on a highly charged electret film. A power generation film, a second electrode formed on a fixed side facing the electret film, a rectifier circuit that converts a voltage generated in the first electrode and the second electrode by a swinging motion of the power generation film into direct current, and A voltage converter that converts the converted DC voltage into a predetermined voltage and a power storage unit that stores the electric charge after the voltage conversion may be provided.

  According to the power generation system of the present invention, the power generation film can be largely bent using kinetic energy such as sound and vibration, so that the power to be generated can be increased and used as a power source for portable devices and the like. In addition, according to the power generation system of the present invention, it is possible to generate power for a portable device without forcing the user to perform an operation for power generation.

It is a block diagram which shows the structure of the electric power generation system which concerns on this invention. It is sectional drawing of the electric power generation film used for the electric power generation system which concerns on this invention. It is sectional drawing of the electric power generating apparatus which converts the kinetic energy of a sound into an electrical energy. It is a side view of the electric power generating apparatus which converts the kinetic energy by a vibration into an electrical energy. It is a figure which shows the front view of the electric power generation film used for the electric power generation system which concerns on this invention, the right view, and a rear view. It is a side view of the electric power generating apparatus which converts the kinetic energy by a vibration into an electrical energy. It is a figure which shows the Example which applied the electric power generating apparatus shown in FIG. 6 to the asymmetric rotary body. It is a figure which shows the Example which mounted the capacitor type power generating element in the asymmetric rotary body.

  Next, an embodiment of a power generation system according to the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

  FIG. 1 is a block diagram showing the configuration of a power generation system according to the present invention. As shown in FIG. 1, a power generation system 10 according to the present invention converts a kinetic energy such as sound and vibration into electrical energy, and converts an AC voltage generated by the bending motion of the power generation film 14 into a DC voltage. Used in a portable device, a rectifier circuit 20 that performs voltage regulation, a regulator 22 that stabilizes a DC voltage, a voltage converter 24 that converts a DC voltage into a predetermined voltage, a power storage means 26 that stores electric charge after voltage conversion, and the like. And a device power supply controller 28 for adjusting the voltage.

  The power storage means 26 is a power source for portable equipment, and for example, a secondary battery such as a lithium ion battery or a large capacity capacitor such as an electric double layer capacitor can be used. As the rectifier circuit 20, a half-wave rectifier circuit or a full-wave rectifier circuit can be used.

  In FIG. 2, sectional drawing of the electric power generation film 14 used for the electric power generation system 10 which concerns on this invention is shown. As shown in FIG. 2, the power generation film 14 includes a ferroelectric thin film 12 capable of performing a bending motion, a first electrode 16 formed on the surface of the thin film 12, and a second electrode 17 formed on the back surface. And a protective layer 18 formed on the surface of each of the first electrode 16 and the second electrode 17. The protective layer 18 can be made of an insulating resin such as PE (polyethylene) or PP (polypropylene).

  The ferroelectric thin film 12 is a resin film polarized in the thickness direction shown in FIG. 2, and a sheet material such as PVDF (Poly Vinylidene Difluoride) can be used. By applying a high voltage through the first electrode 16 and the second electrode 17 respectively formed on the front and back of the thin film 12, the thin film 12 can be polarized in the thickness direction to have piezoelectricity. In addition, although it does not specifically limit about the 1st electrode 16 and the 2nd electrode 17, Metal materials, such as Ni-Cu, Ag, Ag-Pd, can be used.

  When the piezoelectric thin film 12 is bent and deformed to cause mechanical strain in the polarization direction, electric charges are generated on the surface of the thin film 12 to enable power generation. In addition, the thin film 12 has a low mechanical Q and low acoustic impedance, so that although the resonance gain is small, it can gain in a wide frequency range and picks up minute sound waves. Or, it is possible to pick up minute vibrations and convert them into electric power. In addition, by using a resin-based material as the thin film 12, it is easy to mount on a flexible structure, and the shape can be relatively freely molded.

  When the thin film 12 is vibrated by kinetic energy, a pseudo AC voltage is generated on the first electrode 16 and the second electrode 17 formed on the front and back of the thin film 12. Since AC voltage is difficult to handle as a power source for portable devices, it is necessary to convert it to a DC power source. Therefore, a DC voltage stabilized by the regulator 22 can be obtained through the rectifier circuit 20 shown in FIG. Thereafter, the voltage is raised or lowered by the voltage converter 24 to a required voltage, and the power storage means 26 serving as a power source for portable equipment is charged. Although it is possible to supply power directly to each device mounted on a portable device without going through the power storage means 26, it is difficult to keep the power generation film 14 vibrated at all times. There is no. Therefore, it is appropriate to charge the power storage means 26 mounted on the portable device.

  In place of the power generation film 14 using the ferroelectric thin film 12, a capacitor-type power generation element using a highly charged electret film may be used. Specifically, a power generation film that is arranged on an asymmetric rotator that performs oscillating motion by receiving kinetic energy and has a first electrode formed on a highly charged electret film, and a first film formed on a fixed side facing the electret film. Two electrodes, a rectifier circuit that converts the voltage generated in the first electrode and the second electrode by the swing motion of the power generation film into direct current, a voltage converter that converts the converted direct current voltage into a predetermined voltage, and You may comprise so that the electrical storage means which accumulate | stores the electric charge after the voltage conversion may be provided.

  Capacitor-type power generation elements are mainly used as a negative electrode because they are excellent in charge retention performance of negative charges, and capacitors are formed using a positive electrode as a metal material. The electric charge can be taken out by applying a force in the direction of decreasing the capacitor capacity and displacing it. And the vibration excited by the movement of a human body, an exercise | movement, etc. can be converted into a deformation | transformation of a power generation film, and electric power can be taken out.

  FIG. 3 shows a cross-sectional view of a power generator 40 that converts sound kinetic energy into electrical energy. As shown in FIG. 3, the power generation device 40 includes a power generation film 14 that converts sound kinetic energy, which is vibration of air, into electrical energy, and a case 42 that holds the power generation film 14. When the power generation film 14 receives sound pressure from the left direction shown in FIG. 3, the power generation film 14 vibrates and receives power via the first electrode 16 and the second electrode 17 (see FIG. 2) formed on the front and back of the power generation film 14. Can be output.

  When a highly charged electret film is used as the power generation film 14, instead of forming the second electrode of the negative electrode on the back surface of the power generation film 14 (the inner surface of the case 42 shown in FIG. 3), the power generation film 14 It is also possible to provide a negative fixed electrode 44 (indicated by a broken line in FIG. 3) at a separated position on the back side.

  In FIG. 4, the side view of the electric power generating apparatus 51 which converts the kinetic energy by a vibration into an electrical energy is shown. As shown in FIG. 4, the power generation device 51 has one end fixed at a fixed end 52 and a power generation film 55 molded in a bellows shape having a plurality of curved portions, and a curved motion arranged at the free end of the power generation film 55. A weight 56 for increasing the amplitude and a cylindrical displacement restraining mechanism 58 that restricts the vibration direction of the power generation film 55 and the weight 56 to the L direction shown in FIG. 4 are provided. Since the power generation film 55 formed in a bellows shape has a spring constant in the L direction shown in FIG. 4, the weight 56 can be held at a predetermined position against gravity.

  The fixed end 52 of the power generation film 55 is fixed to a casing or the like of a portable device carried by the user. When the portable device vibrates in the L direction shown in FIG. 4, the weight 56 vibrates in the L direction shown in FIG. 4 with respect to the casing of the portable device. Then, a relative displacement occurs between the casing of the portable device and the weight 56, and the power generation film 55 performs an expansion / contraction motion. At this time, since the bending motion is continuously generated in the power generation film 55, power generation can be efficiently performed by the vibration of the portable device. The weight 56 is preferably attached to the first electrode 16 or the second electrode 17 (see FIG. 2) formed on the front and back of the power generation film 55.

  Next, another configuration example of the power generation film will be described. FIG. 5 shows a front view, a right side view, and a rear view of a power generation film 54 that can be used in the power generation system 10 according to the present invention. As shown in FIG. 5, the power generation film 54 includes a ferroelectric thin film 12 capable of performing a bending motion, a first electrode 16 a and a second electrode 17 a formed on the first surface of the thin film 12, The first electrode 16b and the second electrode 17b formed on the second surface of the thin film 12 are configured.

  The output line of the first electrode 16a shown in the front view of FIG. 5 and the output line of the first electrode 16b shown in the rear view are connected before being input to the rectifier circuit 20 in the subsequent stage. Similarly, the output line of the second electrode 17a shown in the front view and the output line of the second electrode 17b shown in the rear view are connected before being input to the rectifier circuit 20 in the subsequent stage.

  By configuring the electrodes of the power generation film 54 in this way, the convex inner peripheral electrodes of the power generation film 54 shown in the right side view of FIG. 5 are always the first electrodes 16a and 16b. The convex outer peripheral electrodes are always the second electrodes 17a and 17b.

  Although not shown in FIG. 5, protective layers are formed on the surfaces of the first electrodes 16a and 16b and the second electrodes 17a and 17b, respectively. For this protective layer, an insulating resin such as PE or PP can be used. The ferroelectric thin film 12 may be a PVDF sheet material polarized in the thickness direction, as described with reference to FIG.

  In FIG. 6, the side view of the electric power generating apparatus 50 which converts the kinetic energy by a vibration into an electrical energy is shown. As shown in FIG. 6, the power generation device 50 is fixed at a fixed end 52 and has a power generation film 54 molded into a bellows shape having a plurality of curved portions, and a curved motion arranged at the free end of the power generation film 54. A weight 56 for increasing the amplitude and a cylindrical displacement restraining mechanism 58 that restricts the vibration direction of the power generation film 54 and the weight 56 to the L direction shown in FIG. 6 are provided. The power generation film 54 has the structure described with reference to FIG. Since the power generation film 54 formed in a bellows shape has a spring constant in the L direction shown in FIG. 6, the weight 56 can be held at a predetermined position against gravity.

  The fixed end 52 of the power generation film 54 is fixed to a casing of a portable device carried by the user. When the portable device vibrates in the L direction shown in FIG. 6, the weight 56 vibrates in the L direction shown in FIG. 6 with respect to the casing of the portable device. Then, a relative displacement occurs between the casing of the portable device and the weight 56, and the power generation film 54 performs an expansion / contraction motion. At this time, since the bending motion is continuously generated in the power generation film 54, a potential difference is generated between the first electrodes 16a and 16b and the second electrodes 17a and 17b shown in FIG. In addition, power generation can be performed efficiently. The weight 56 is preferably attached to the first electrodes 16a and 16b or the second electrodes 17a and b (see FIG. 5) formed on the front and back of the power generation film 54.

  Next, FIG. 7 shows an embodiment in which the power generator 50 shown in FIG. 6 is applied to the asymmetric rotating body 62 so that the weight 56 automatically faces the direction of gravity. As shown in FIG. 7, the asymmetric rotating body 62 that can swing in the R direction has a mass moment that is unbalanced with respect to the rotating shaft 63. The fixed end 52 of the power generation film 54 is fixed to the asymmetric rotating body 62. The displacement restraint mechanism 58 limits the vibration direction of the power generation film 54 and the weight 56 to the L direction shown in FIG.

  As shown in FIG. 7, when the power generation device 50 is applied to an asymmetric rotating body, the weight 56 is automatically directed in the direction of gravity. And the direction dependence of the portable apparatus carrying the electric power generating apparatus 50 is excluded, and electric power generation can be continued efficiently.

  Next, an embodiment in which a capacitor-type power generating element that converts kinetic energy such as vibration into electric energy is mounted on the asymmetric rotating body 72 will be described with reference to FIG. In the embodiment shown in FIG. 8, the above-described capacitor-type power generation elements are used as the power generation films 74, 75, and 76, the positive first electrode 16 is formed on the asymmetric rotating body 72, and the housing side of the fixed portable device A negative second electrode 17 (indicated by a broken line in FIG. 8) is formed.

  The asymmetric rotating body 72 that can swing in the R direction has an unbalanced mass moment with respect to the rotating shaft 73 as shown in FIG. The power generation films 74, 75, and 76 are fixed to the asymmetric rotating body 72. With this configuration, when the portable device is swung, the asymmetric rotating body 72 is swung, and power is generated according to this swing. Furthermore, the first electrode 16 of the divided power generation films 74, 75 and 76 can be damped, and the power generation film 54 as shown in FIG. Etc. can be omitted.

  It should be noted that the present invention is not limited to the configuration of the embodiment described above, and of course includes various variations and modifications that can be made by those skilled in the art within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Power generation system 12 Thin film 14, 54, 55, 74, 75, 76 Power generation film 16, 16a, 16b 1st electrode 17, 17a, 17b 2nd electrode 18 Protective layer 20 Rectifier circuit 22 Regulator 24 Voltage converter 26 Power storage means 28 Equipment power controller 40, 50, 51 Power generation device 42 Case 44 Fixed electrode 52 Fixed end 56 Weight 58 Displacement restraint mechanism 62, 72 Asymmetric rotating body 63, 73 Rotating shaft

Claims (6)

In a power generation system that converts kinetic energy into electrical energy,
A ferroelectric thin film that receives the kinetic energy and performs a bending motion, a power generation film composed of a first electrode and a second electrode formed on the front and back of the thin film,
A rectifier circuit for converting the voltage generated in the first electrode and the second electrode by the bending motion of the thin film into direct current;
A voltage converter that converts the converted DC voltage into a predetermined voltage;
And a power storage means for storing the charge after the voltage conversion. The power generation system according to claim 1,
The power generation system, wherein the power generation film is molded into a bellows shape having a plurality of curved portions. The power generation system according to claim 1 or 2,
A power generation system comprising a weight for increasing an amplitude of the bending motion in a part of the power generation film. The power generation system according to claim 3,
The power generation system, wherein the weight is attached to a first electrode or a second electrode in the power generation film. The power generation system according to claim 2, wherein
The power generation system, wherein a fixed end of the power generation film is fixed to an asymmetric rotating body having an unbalanced mass moment with respect to a rotation axis. In a power generation system that converts kinetic energy into electrical energy,
A power generation film that is arranged on an asymmetric rotating body that performs rocking motion in response to the kinetic energy, and in which a first electrode is formed on a highly charged electret film;
A second electrode formed on the fixed side facing the electret film;
A rectifier circuit that converts a voltage generated in the first electrode and the second electrode by a swinging motion of the power generation film into a direct current;
A voltage converter that converts the converted DC voltage into a predetermined voltage;
And a power storage means for storing the charge after the voltage conversion.

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