JP6019981B2 - Power generation device and sensing system - Google Patents

Description

  The present invention relates to a power generation device and a sensing system using mechanical vibration.

  In recent years, the development of so-called renewable energy sources such as solar power generation, wind power generation, geothermal power generation, and wave power generation that extract energy from the natural environment within a range that can be repeatedly used has attracted attention.

  At the same time, energy harvesting technology that uses various minute energy in nature for electricity is attracting attention. This energy harvesting is a technology that collects waste or unused energy used in nature or other work as electric energy, such as “harvest” (for example, Patent Document 1 or Patent Document 2). reference).

  As such energy harvesting, a technique for converting waste heat into electricity using a thermoelectric conversion element and a technique for converting mechanical vibration in an environment such as bridge vibration into electric energy are known. As a power generation device that converts mechanical vibrations into electrical energy, electromagnetic force, that is, a combination of a relatively movable magnetic body and an inductance such as a coil, a piezoelectric element, an electrostatic force (MEMS, electret), or the like is used. Things.

  Conventionally, many of these types of vibration power generation devices have a resonator element, and the resonance frequency is governed by the resonator element and its own weight or added weight. In this structure, the weight exhibits the maximum amplitude at the vibration resonance frequency, and the electrical output increases. Using these power generation devices, it is expected to extract electric energy from an object having mechanical vibration sources with various frequencies.

JP 2012-097673 A JP 2011-097661 A

  However, in the conventional vibration type power generation device, there is a problem that the output due to vibration decreases when the vibration source deviates from the resonance frequency of the power generation device. On the other hand, when a vibration type power generation device is designed for each resonance frequency, there is a problem that it is difficult to reduce the cost because the versatility is lost.

  Therefore, in a power generation device that converts mechanical vibration energy into electrical energy, an object is to extract electrical energy that does not depend on the natural vibration frequency of the power generation device from a mechanical vibration source having an indefinite frequency.

  From one aspect to be disclosed, a rigid body and a closed container that accommodates the rigid body in a movable state are provided, and the closed container has a rigidity lower than that of the rigid body and converts collision energy of the rigid body into heat. A heat conversion layer; a heat storage layer covering an outer surface of the heat conversion layer; a heat insulating layer covering an outer surface of the heat storage layer and having an opening; and a thermoelectric provided in contact with the heat storage layer. A power generation device comprising a conversion element is provided.

  From another viewpoint to be disclosed, there is provided a sensing system comprising a vibration source, the above-described power generation device fixed to the vibration source, and a sensor element using the power generation device as a power source. The

  According to the disclosed power generation device and sensing system, it is possible to extract electrical energy that does not depend on the natural vibration frequency of the power generation device from a mechanical vibration source having an indefinite frequency.

1 is a schematic cross-sectional view of a power generation device according to an embodiment of the present invention. It is a schematic sectional drawing of the vibration type electric power generation device of Example 1 of this invention. It is explanatory drawing of the thermoelectric conversion module mounted in the vibration type electric power generating device of Example 1 of this invention. It is a schematic sectional drawing of the vibration type electric power generating device of Example 2 of this invention. It is a schematic sectional drawing of the vibration type electric power generation device of Example 3 of this invention. It is a notional block diagram of the sensing system of Example 4 of this invention.

  Here, with reference to FIG. 1, the electric power generation device of embodiment of this invention is demonstrated. FIG. 1 is a conceptual cross-sectional view of a power generation device according to an embodiment of the present invention. The power generation device 10 includes a rigid body 16, a closed container 11 that accommodates the rigid body 16 in a movable state, and a thermoelectric conversion element 20. The closed container 11 includes a heat conversion layer 12 that converts the collision energy of the rigid body 16 into heat, a heat storage layer 13 that covers the outer periphery of the heat conversion layer 12, and a heat insulating layer 14 that covers the outer periphery of the heat storage layer 13 and has an opening 15. Have

The opening 15 is provided with a thermoelectric conversion element 20 in contact with the heat storage layer 13, and if necessary, a heat radiating member 21 is provided on the surface opposite to the surface in contact with the heat storage layer 13 of the thermoelectric conversion element 20. It is taken out from the pair of electrical output lines 22 ₁ and 22 ₂ .

  The shape of the movable space formed by the inner wall of the heat conversion layer 12 is arbitrary, but is typically cylindrical, and is formed of two members for inserting the rigid body 16 therein. For example, two members obtained by dividing a cylinder vertically may be used, two members obtained by dividing a cylinder horizontally, or a combination member of an empty can-like portion and a lid portion.

  As the heat conversion layer 12, an elastic member, for example, an elastomer such as a rubber elastic body or a polymer compound having viscoelasticity is used. When the rigid body 16 is moved by vibration and collides with the heat conversion layer 12, the rigid body 16. It absorbs a part of the kinetic energy of and converts it into heat. The heat conversion layer 12 may also be two members that are vertically divided into cylinders, may be two members that are horizontally divided into cylinders, or may be a combination member of an empty can-like portion and a lid portion.

  As the heat storage layer 13, under the temperature environment exposed during power generation (when the external temperature is 20 to 40 ° C. and the temperature rises in the range of 0 to 20 ° C. due to heat generated by vibration, the operating temperature range of the heat storage layer is It is desirable to use a material with a large specific heat), and the larger the specific heat, the larger the amount of heat stored per unit volume. When used near room temperature, it is preferable to use Cu or a metal material having a larger specific heat than Cu. desirable. In the vicinity of 300 K, the specific heat of Cu is 0.39 J / (g · K), so 0.88 J / (g · K) Al, 0.44 J / (g · K) Fe, or 0.55 J / (G · K) Ti or the like is preferable, but Cu or Al is more preferable from the viewpoint of cost and workability. The heat storage layer 13 may also be two members that are vertically divided into cylinders, may be two members that are horizontally divided into cylinders, or may be a combination member of an empty can-like portion and a lid portion.

  As the heat insulating layer 14, a foam material, super insulation, vacuum heat insulating, or a combination thereof is used. The heat insulating layer 14 is provided with an opening 15 in at least one place, and the thermoelectric conversion element 20 is inserted into the opening so that the thermoelectric conversion element 20 and the heat storage layer 13 are in contact with each other. The heat insulating layer 12 may also be two members that are vertically divided into cylinders, may be two members that are horizontally divided into cylinders, or may be a combination member of an empty can-like portion and a lid portion.

  As the thermoelectric conversion element 20, a Seebeck effect element is typically used, and it is desirable to provide a heat dissipation member 21 on the surface opposite to the surface in contact with the heat storage layer 13 of the thermoelectric conversion element 20. Heat dissipation. As the heat radiating member 21, it is desirable to use a metal fin mainly composed of Cu or Al.

  The rigid body 16 is preferably a hard material having a large rigidity, such as carbon steel or YSZ (yttria stabilized zirconia). The shape is typically spherical, but is not limited to a spherical shape, and the number of rigid bodies 16 accommodated in the sealed container 11 may be one or plural.

  When a plurality of rigid bodies 16 are accommodated, the larger the rigidity factor of the rigid bodies 16 is, the closer the collision between the rigid bodies is to an elastic collision, so that the kinetic energy is hardly lost. Therefore, the kinetic energy of the rigid body 16 due to vibration when it collides with the heat conversion layer 12 is efficiently converted into heat in the heat conversion layer 12.

The heat converted in the heat conversion layer 12 is transmitted to the heat storage layer 13 to be stored, and the heat stored in the heat storage layer 13 is transferred to the contact portion with the thermoelectric conversion element 20 and converted into electric energy to be It is taken out from the output lines 22 ₁ and 22 ₂ .

  In this way, by applying mechanical vibration to the power generation device 10 of the present invention, the rigid body 16 accommodated therein repeatedly collides with the heat conversion layer 12 to generate and store heat, and the temperature inside and outside the sealed container 11. Power is generated by the difference.

  In this case, since the rigid body 16 can move without its own resonance in the three-dimensional motion, the power generation efficiency of the power generation device 10 can suppress the influence of the vibration frequency of the mechanical vibration caused by the external force.

Here, the performance of the power generation device according to the embodiment of the present invention is evaluated under various preconditions.
(1) The maximum relative speed given by the external force is 1.0 m / s, the vibration frequency is 50 Hz, the collision is 100 times / s, the mass of the rigid body is 10 g, the inner dimension of the sealed container 11, that is, the heat conversion. Cubic whose inner dimensions are 4 cm on a side, the thickness of the heat insulating layer 14 is 5 cm, and the heat conductivity of the heat insulating layer 14 is 0.0010 to 0.0013 Wm ⁻¹ K ⁻¹ (a heat insulating layer using a metal sheet as an outer wall) In this case, the glass fiber fibers are arranged so as to hold the outer shape of the heat insulating member and evacuated, and the figure of merit ZT = 1 of the thermoelectric conversion element 20 is set. When operating near room temperature under such conditions, when the energy converted into heat per hour is about 1 W and the temperature difference between the inner surface and the outer surface of the heat insulation layer 14 is about 0.43 ° C., the heat insulation layer The heat energy dissipated via 14 can be calculated to be about 1 W, and a temperature equilibrium state is reached. Note that the simple may be commercially available insulation panels the thermal conductivity called 0.01~0.001Wm ^-1 K ^-1 range of Vacuum Insulation Panel (VIP).

(2) Among the preconditions of (1) above, when the thickness of the heat insulation layer is 2.5 cm, the frequency is increased and the collision is changed to 600 times at a steady frequency of 300 Hz, the heat is converted into heat per time. The energy is about 6W. When the temperature difference between the inner surface and the outer surface of the heat insulating layer 14 is about 1.3 ° C., the heat energy dissipated through the heat insulating layer 14 can be calculated as about 6 W, and a temperature equilibrium state is obtained.

(3) If the heat radiation side is in an ideal state the same as outside air temperature, 1.3 ° C. is equal to the temperature difference T _h -T _c of the heat absorption side and the heat radiating side of the thermoelectric conversion element 20, a thermoelectric of ZT~1.0 Since the conversion efficiency of the conversion element 20 is converted to about 0.728%, in the case of a thermoelectric conversion element having an area of 3 cm ² , the output is calculated to be about 270 μW.

(4) Among the preconditions of (3) above, if the heat dissipation efficiency is not ideal and the temperature difference between the heat absorption side and the heat dissipation side is half of 1.3 ° C. Is about 67.5 μW.

(5) Among the preconditions of the above (3), the thickness of the heat insulation layer 14 is 0.5 cm, the closed container 11 is vacuum insulated, and the heat emissivity of the heat insulation wall surface is set to 0. 0 by mirror finishing of a metal surface such as aluminum. If the temperature difference is 1.0 ° C., the heat conduction of the vacuum heat insulating layer is estimated to be about 1.8 μW / m ² . 0.0010 to 0.0013 Wm ⁻¹ K ⁻¹ heat insulation layer (to keep the outer shape of the heat insulation member with glass fiber fibers inside the heat insulation layer with a metal sheet such as 0.2 mm thick stainless steel SUS304 as the outer wall The heat conduction member of the heat-insulating member having a structure that is vacuum-evacuated by placing it in the same manner, and a commercially available example of the same thermal conductivity: U-Vacua (thermal conductivity 0.0012 Wm ⁻¹ K ⁻¹ , manufactured by Panasonic Corporation) is 2 Since the thickness is 0.048 W / m ² when the thickness is 0.5 cm, the thickness of the heat insulating material can be reduced by optimizing the design.

  Such a power generation device is combined with a sensor and transmitter such as a temperature sensor, a humidity sensor, or a vibration sensor, and the output of the power generation device is used as a power source for the sensor and the transmitter, so that no external power source or battery is required. A system can be constructed.

  Next, with reference to FIG.2 and FIG.3, the vibration type electric power generation device of Example 1 of this invention is demonstrated. FIG. 2 is a schematic cross-sectional view of the vibration power generation device according to the first embodiment of the present invention. The vibration power generation device 30 includes a sealed container 31, a YSZ sphere 36 accommodated in the sealed container 31, a thermoelectric device. A conversion module 40 is provided. On the heat radiation side of the thermoelectric conversion module 40, Al heat radiation fins 46 are provided in order to increase the heat radiation efficiency.

  The sealed container 31 includes an elastomer layer 32 serving as a heat conversion layer, a heat insulating layer housing 34 provided with an Al heat storage layer 33 and an opening 35, and in the opening 35, the heat absorption side of the thermoelectric conversion module 40 is made of Al. Provided in contact with the heat storage layer 33. In addition, the elastomer layer 32 and the Al heat storage layer 33 are formed by a member divided into two horizontal parts, and the heat insulating layer casing 34 is formed by a member divided into two horizontal parts having an insertion structure at the end like a tea can. doing.

  The inner dimensions of the elastomer layer 32 are 45 mm in diameter, 45 mm in height, and 25 mm in thickness. The Al heat storage layer 33 has a thickness of 2 mm, and the heat insulation layer housing 34 has a thickness of 30 mm. The size of the opening 35 is 3 mm × 3 mm. The diameter of the YSZ sphere 36 accommodated in the closed space is 15 mm.

FIG. 3 is an explanatory diagram of a thermoelectric conversion module mounted on the vibration power generation device according to the first embodiment of the present invention, FIG. 3A is a perspective view of the power generation unit, and FIG. 3B is a heat conversion module. FIG. As shown in FIG. 3A, the power generation unit includes a p-type thermoelectric conversion material member 41 made of Bi ₂ Te _{3 having a} size of 100 μm × 100 μm × height 200 μm and Bi _0.3 Sb _{1 having a} size of 100 μm × 100 μm × height 200 μm. _.7 Te ₃ n-type thermoelectric conversion material member 42 formed by vacuum EB deposition to a thickness of 0.5 .mu.m, Ni film or Ni-Cu alloy film intervenes as an interface metal layer, and consists of an interface metal layer and a Cu film. The electrode 43 is formed by heat bonding with a solder material having a melting point of 200 ° or less. The Cu film, this forms a wiring pattern by screen printing on the pre-ceramic plate 44 1 of the plate thickness 0.25mm, such as _alumina, 44 ₂ prior to bonding, previously formed by firing in a reducing atmosphere. 3A shows a pair of thermoelectric elements each including one p-type member and one n-type member.

As shown in FIG. 3 (b), such a power generation unit is arranged so that p-type thermoelectric conversion members 41 and n-type thermoelectric conversion members 42 are alternately adjacent to each other and connected in series by electrodes 43, and ceramics are formed above and below them. Plates 44 ₁ and 44 ₂ are provided. In addition, the electric output lines 45 ₁ and 45 ₂ are connected to the electrode 43 at the final end serving as the output unit to form a thermoelectric conversion element module. In FIG. 3B, for simplicity of illustration, the case of 8 pairs is shown, but 0.07 to 0.08 V / ° C. can be obtained by using 200 pairs, for example. If it is 20 mV or more, the voltage is boosted to, for example, 1 to 4 V and a constant voltage is output according to a required drive voltage of a normal electronic circuit by a DC / DC boost converter.

  As described above, in the first embodiment of the present invention, the mechanical vibration is converted into the collision motion of the YSZ sphere 36 accommodated in the closed space, and this motion energy is converted into heat by the collision with the elastomer layer 32. Therefore, even if it contacts with the vibration source which vibrates with what kind of vibration period, it can convert into electric energy efficiently, without being influenced by the vibration period.

  In the first embodiment, the closed space is the atmospheric pressure, but the influence of the gas on the vibration state can be reduced, the motion interference between the gas and the rigid body can be reduced, and the resonance of the rigid body shape and the gas is generated. Therefore, a vacuum state or a gas having less viscosity than air such as a rare gas may be sealed.

  Next, the vibration type power generation device of Example 2 of the present invention will be described with reference to FIG. 4. The vibration type power generation device of Example 2 is the same as the vibration type power generation device of Example 1 described above. Are the same and differ in the number of rigid materials contained in the enclosed space.

  FIG. 4 is a schematic cross-sectional view of the vibration power generation device according to the second embodiment of the present invention. Like the first embodiment, the vibration power generation device 30 includes an elastomer layer 32, an Al heat storage layer 33, and a heat insulation layer casing. The thermoelectric conversion module 40 arrange | positioned in the airtight container 31 provided with 34 and the opening part 35 provided in the heat insulation layer housing | casing 34 is provided. On the heat radiation side of the thermoelectric conversion module 40, Al heat radiation fins 46 are provided in order to increase the heat radiation efficiency. However, in Example 2, a plurality of carbon steel balls 37 having a diameter of 7.14 mm (inch nominal diameter 9/32) are accommodated in the closed space. Here, the number of carbon steel balls 37 to be accommodated is seven, but the size and number of the carbon steel balls 37 are not limited to 7.14 mm and seven as long as the inside of the closed container 31 can be moved. .

In Example 2 of the present invention, a plurality of carbon steel balls 37 are accommodated, but the collision between the carbon steel balls 37 is close to an elastic collision, so that the kinetic energy changes to thermal energy due to the collision between the balls. The ratio is smaller than that in the case of colliding with the elastomer layer 32. On the other hand, the kinetic energy of the carbon steel ball 37 is converted into heat relatively efficiently in the elastomer layer 32 when it collides with the elastomer layer 32. Moreover, compared with the case where the number of the carbon steel balls 37 is one, the direction of the reaction force and the collision timing when the container is moved and the carbon steel balls 37 collide with the inner wall of the container are easily dispersed. In place of the carbon steel balls 37, YSZ spheres that can obtain high fracture toughness (about 5.0 MPam ^1/2 ) and high bending strength (1.0 GPa or more) among ceramic materials can also be used.

  Next, the vibration type power generation device according to the third embodiment of the present invention will be described with reference to FIG. 5, but the basic configuration is the same as that of the vibration type power generation device according to the first embodiment described above. An adhesive layer is provided at the bottom.

  FIG. 5 is a schematic cross-sectional view of the vibration power generation device according to the third embodiment of the present invention. Like the first embodiment, the vibration power generation device 30 includes an elastomer layer 32, an Al heat storage layer 33, and a heat insulation layer casing. The thermoelectric conversion module 40 arrange | positioned in the airtight container 31 provided with 34 and the opening part 35 provided in the heat insulation layer housing | casing 34 is provided. On the heat radiation side of the thermoelectric conversion module 40, Al heat radiation fins 46 are provided in order to increase the heat radiation efficiency.

  However, in Example 3, an adhesive layer 38 is provided at the bottom of the heat insulating layer casing 34, and a release sheet 39 is provided so as to protect the adhesive layer 38. In use, the release sheet 39 is peeled off, and the vibration power generation device 30 may be attached to the vibration source by the exposed adhesive layer 38.

  In Example 3 of the present invention, since the adhesive layer 38 is provided in advance, when the vibration power generation device is fixed to a vibration source such as a bridge or a motor, a fixing device such as a fastening member is not required, and one-touch. Can be installed.

Next, with reference to FIG. 6, the sensing system of Example 4 of this invention is demonstrated. FIG. 6 is a conceptual configuration diagram of the sensing system according to the fourth embodiment of the present invention, in which the vibration power generation device 30 is fixed to the vibration source 50 and the alarm module 60 including the sensor 61 and the transmitter 62 is provided. Fix it. The module 60 also includes a power supply unit on which a DC-DC boost converter, a voltage regulator, a secondary storage battery or an electric double layer capacitor are mounted, and a control circuit unit on which a microcontroller is mounted. Electric power is supplied to the alarm module 60 from the vibration power generation device 30 via the electric output lines 45 ₁ and 45 ₂ . Here, the vibration type power generation device 30 shown in Example 3 is used as the vibration type power generation device, and the adhesive layer 38 is used to fix the vibration type power generation device 30 to the vibration source 50.

  For example, the vibration power generation device 30 is fixed to a vibration source 50 such as a bridge, and the vibration is converted into electric energy. When a vibration sensor is used as the sensor 61, a change in gravitational acceleration due to an earthquake different from the vibration of the vibration source is detected, and the detection result is notified as earthquake information to the vehicle traveling on the bridge by the transmitter 62. be able to.

  As described above, in the fourth embodiment of the present invention, the vibration type power generation device is used as the power source of the sensing system. Disappear.

  In the fourth embodiment, the power source of the earthquake warning system provided on the bridge is described. However, the vibration source may be a motor, a machine tool, or the like, and a temperature sensor or a humidity sensor may be used as the sensor. . In this case, local temperature management and humidity management can be easily performed by fixing the vibration power generation device and the alarm module at a local location of the motor or machine tool.

Here, the following supplementary notes are attached to the embodiments of the present invention including Examples 1 to 4.
(Additional remark 1) It is provided with the rigid body and the closed container which accommodates the said rigid body in a movable state, and the said closed container has a rigidity rate lower than the rigid modulus of the said rigid body, and converts the collision energy of the said rigid body into heat | fever A heat storage layer covering the outer surface of the heat conversion layer, a heat insulating layer covering the outer surface of the heat storage layer and having an opening, and a thermoelectric conversion element provided in the opening and contacting the heat storage layer A power generation device comprising:
(Supplementary note 2) The power generation device according to supplementary note 1, wherein a plurality of the rigid bodies are accommodated.
(Additional remark 3) The said heat conversion layer consists of a high molecular compound which has an elastomer or a viscoelasticity, The electric power generating device of Additional remark 1 or Additional remark 2 characterized by the above-mentioned.
(Supplementary note 4) The power generation device according to any one of supplementary notes 1 to 3, wherein the heat storage layer is made of a metal or an alloy having the same specific heat as Cu or a specific heat larger than Cu.
(Supplementary note 5) The power generation device according to any one of supplementary notes 1 to 4, wherein the rigid body is made of carbon steel or yttria-stabilized zirconia.
(Supplementary note 6) In any one of Supplementary notes 1 to 5, wherein the adhesive layer includes an adhesive layer provided on at least a part of the outside of the heat insulating layer, and a release sheet provided on the surface of the adhesive layer. The described power generation device.
(Supplementary note 7) Sensing comprising: a vibration source; the power generation device according to any one of supplementary notes 1 to 5 fixed to the vibration source; and a sensor element using the power generation device as a power source. system.
(Supplementary note 8) A vibration source, the power generation device according to supplementary note 6 fixed by the adhesive layer in a state where the release sheet is peeled off from the vibration source, and a sensor element using the power generation device as a power source. Sensing system characterized by
(Supplementary note 9 ) The sensing system according to supplementary note 8 , further comprising a transmitter that transmits a detection result of the sensor element, wherein the transmitter uses the power generation device as a power source.

10 harvesting device 11 enclosure 12 heat conversion layer 13 heat storage tank 14 thermal insulation layer 15 openings 16 rigid 20 thermoelectric conversion element 21 radiating member ₂₂ 1, 22 ₂ electrical output lines 30 vibratory generator device 31 sealed container 32 the elastomeric layer 33 Al heat storage Layer 34 heat insulation layer housing 35 opening 36 YSZ sphere 37 carbon steel ball 38 adhesive layer 39 release sheet 40 thermoelectric conversion module 41 p-type thermoelectric conversion member 42 n-type thermoelectric conversion member 43 electrodes 44 ₁ , 44 ₂ ceramic plate 45 ₁ , 45 ₂ Electric output line 46 Al heat radiating fin 50 Vibration source 60 Alarm 61 Sensor 62 Transmitter

Claims (6)

A rigid body,
A closed container for accommodating the rigid body in a movable state;
The closed container has a heat conversion layer that converts the collision energy of the rigid body into heat, the rigidity of which is lower than the rigidity of the rigid body,
A heat storage layer covering the outer surface of the heat conversion layer;
A power generation device comprising: a heat insulating layer that covers an outer surface of the heat storage layer and has an opening; and a thermoelectric conversion element that is provided in the opening and contacts the heat storage layer.   The power generation device according to claim 1, wherein a plurality of the rigid bodies are accommodated.   The power generation device according to claim 1, wherein the heat storage layer is made of a metal or alloy that is the same as Cu or has a specific heat larger than Cu. An adhesive layer provided on at least a part of the outside of the heat insulating layer;
It has a peeling sheet provided in the surface of the said adhesion layer, The power generation device of any one of Claim 1 thru | or 3 characterized by the above-mentioned. A vibration source;
The power generation device according to any one of claims 1 to 3 , which is fixed to the vibration source,
A sensing system comprising a sensor element that uses the power generation device as a power source. A vibration source;
The power generation device according to claim 4 fixed by the adhesive layer in a state where the release sheet is peeled off to the vibration source,
A sensor element using the power generation device as a power source;
Sensing system characterized by comprising

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