JP4876788B2 - Piezoelectric generator - Google Patents

Description

  The present invention relates to a device having a rotating body such as an automobile tire and a power generation mechanism that is attached to the rotating body and generates electric power, and more specifically, is fixed to an inner peripheral surface of the rotating body. In particular, the present invention relates to a piezoelectric power generation apparatus including a piezoelectric element that generates electric power by a piezoelectric effect due to stress when an inner peripheral surface of a rotating body is deformed.

  2. Description of the Related Art Conventionally, various sensors are attached to automobile tires in order to detect tire pressure and temperature. Such a sensor requires a power source for driving the sensor. However, when the power source is incorporated in the tire, the structure is complicated, and there is a risk of increasing the size of the device including the sensor and the power source.

  Therefore, Patent Document 1 below discloses a structure in which a piezoelectric power generation device for supplying electric power to a sensor is provided in a tire. 9A to 9C are schematic front sectional views for explaining the piezoelectric power generation device described in Patent Document 1. FIG.

  As shown in FIG. 9A, the automobile tire 101 is in contact with the road surface 102. In this case, since the tire 101 has elasticity, the portion that is in contact with the road surface 102 is flattened along the road surface.

  On the other hand, as shown in FIG. 9B, the sensor unit 103 is fixed to the inner peripheral surface of the tire 101. The sensor unit 103 has a sensor that detects the pressure and temperature in the tire 101. A power generation device 104 for driving the sensor unit 103 is fixed to the inner peripheral surface of the tire 101. Here, the power generation device 104 is configured by a piezoelectric element. The piezoelectric element is configured using piezoelectric ceramics such as PZT ceramics. A piezoelectric element is configured by forming electrodes on both main surfaces of a plate-like piezoelectric body made of such piezoelectric ceramics. Electric power is taken out along with the bending vibration of the piezoelectric element.

  As shown in FIG. 9B, when the portion where the power generation device 104 is fixed to the inner peripheral surface of the tire 101 is flat, that is, the portion where the tire 101 is in contact with the road surface 102 is located. In this case, no force is applied to the piezoelectric power generation device 104 from the tire 101 side.

On the other hand, as shown in FIG. 9C, when the portion where the power generation device 104 is provided approaches the portion away from the road surface 102 as the tire 101 rotates, the tire 101 is deformed. Therefore, the power generation device 104 is bent along with the deformation of the inner peripheral surface of the tire 101. Such bending deformation is repeated as the tire 101 rotates, and electric power is extracted from the power generation device 104 by bending vibration.
JP 2005-186930 A

  As described above, the power generation device 104 includes a piezoelectric element using piezoelectric ceramics such as PZT ceramics. In general, piezoelectric ceramics tend to be strong against compressive stress and weak against tensile stress. Therefore, as shown in FIG. 9C, the piezoelectric body is not easily destroyed when it is bent, that is, when compressive stress is applied.

  However, as shown in a schematic partial cutaway front sectional view in FIG. 10, for example, when a stone 105 exists on the road surface 102, the tire 101 rides on the stone 105 and deforms as illustrated. That is, the inner peripheral surface of the tire 101 is deformed so as to protrude inward. In this case, a tensile stress is applied to the power generation apparatus 104, and the power generation apparatus 104 made of piezoelectric ceramics may be destroyed.

  In addition, when the piezoelectric element using the bending vibration is used, the thickness of the piezoelectric body cannot be increased so much in order to obtain a large amount of power generation. Therefore, in order to increase the power generation amount, it was necessary to increase the area. Therefore, the piezoelectric power generation device 104 tends to be large and the cost may be high.

  The object of the present invention is to eliminate the above-mentioned conventional drawbacks, and even when the tire rides on a stone or the like, it is difficult to break down, and a sufficient power generation amount can be obtained without causing an increase in size. Another object is to provide a piezoelectric power generator.

  According to the present invention, there is provided a piezoelectric power generation apparatus that generates electric power by a piezoelectric effect as a rotating body rotates, and a rotating body in which a flat portion is generated on an inner peripheral surface as the rotation occurs, and one end in a length direction is the first. The end portion, the other end in the length direction is the second end portion, and is fixed to the inner peripheral surface of the rotating element and the piezoelectric element that generates power by the piezoelectric effect by expanding and contracting in the length direction, And a fixing member to which the first end portion of the piezoelectric body is fixed, and an outer peripheral surface of the rotating body as the rotating body rotates, and is disposed outside the second end portion of the piezoelectric element. Is subjected to stress due to the deformation when deformed from a flat portion to a non-flat portion, and presses the second end of the piezoelectric element so as to compress the piezoelectric element in the length direction according to the stress due to the deformation There is provided a piezoelectric power generation device comprising a pressing member.

  In the piezoelectric power generation device according to the present invention, preferably, the pressing member is positioned on the outer side in the length direction of the piezoelectric body from the second end portion of the piezoelectric element, and the inner peripheral surface of the rotating body is deformed. When stress is applied, the end of the pressing member on the side opposite to the piezoelectric element is separated from an extension line in the length direction of the piezoelectric element with respect to the end of the pressing member on the piezoelectric element side. It moves to an inner side, and the edge part by the side of the said piezoelectric element of the said press member is comprised so that the said 2nd edge part of the said piezoelectric material may be pressed. In this case, the end of the pressing member on the side of the pressing element opposite to the piezoelectric element side serves as a power point, and the portion of the pressing member that is in contact with the fixing member serves as a fulcrum, and the end of the pressing member on the piezoelectric element side As a result, the pressing member presses the second end of the piezoelectric element with a large force so as to compress the piezoelectric element in the length direction. Therefore, the piezoelectric element can be greatly deformed in the length direction, and more electric power can be taken out.

  In the present invention, preferably, the fixing member is a plate-like member fixed to the inner peripheral surface of the rotating body, and the inner side of the rotating body from the first end side of the piezoelectric element of the plate-like member. A fixed wall extending in a direction away from the peripheral surface and to which the first end of the piezoelectric element is fixed, and the fixed wall of the plate-like member are opposite to each other in the length direction of the piezoelectric element. A locking wall that is located outside the second end of the piezoelectric element and extends in a direction away from the inner peripheral surface of the rotating body, and the pressing member A working wall inserted between the inner surface of the locking wall and the second end of the piezoelectric element, and the surface of the working wall on the piezoelectric element side is a second side of the piezoelectric element. Press the end. In this case, the fixing member has a fixing wall and a locking wall, and the action wall of the pressing member is inserted between the inner surface of the locking wall and the second end of the piezoelectric element. Therefore, the portion where the working wall is in contact with the locking wall serves as a fulcrum, and the second end of the piezoelectric element can be pressed by the working wall with a larger force, and more electric power can be taken out. Can do.

  In the present invention, preferably, the pressing member is integrally connected to the fixing member, and the pressing member is easily displaced with respect to the fixing member at a boundary portion between the fixing member and the pressing member. A thin-walled portion is provided. Since the thin portion is provided, the end portion of the pressing member opposite to the piezoelectric element can be easily moved with the thin portion as a fulcrum when the inner peripheral surface of the rotating body is deformed. Therefore, a larger pressing force can be applied to the piezoelectric element, and a larger electric power can be taken out.

  In the present invention, preferably, the fixing member includes a first plate member fixed to an inner peripheral surface of the rotating body, and a first end portion side of the piezoelectric element of the plate member. A fixed wall provided to extend in a direction away from the inner peripheral surface of the rotating body, and a first end of the piezoelectric element is fixed to the fixed wall, and the pressing member includes the rotating body A first plate-like member provided along the inner peripheral surface of the second plate-like member, and a second end side of the piezoelectric element of the second plate-like member in a direction away from the inner peripheral surface of the rotating body. And an end of the pressing member opposite to the piezoelectric element is moved inwardly of the rotating body due to the stress caused by the deformation of the inner peripheral surface of the rotating body. The second end of the piezoelectric element is pressed by the working wall. In this case, the fixing member has a first plate-like member and a fixing wall, and the first end of the piezoelectric element is fixed to the fixing wall, and the second end side of the piezoelectric element , The working wall of the pressing member is opposed, and the end of the pressing member opposite to the piezoelectric element is longer than the extension line in the length direction of the piezoelectric element due to the stress caused by the deformation of the inner peripheral surface of the rotating body. When moving inward of the rotating body, the second end of the piezoelectric element is pressed by the working wall. Therefore, the piezoelectric element can be compressed more effectively, and thereby, a larger electric power can be taken out.

  In the present invention, it is preferable that the piezoelectric element further includes a support member that is laminated on at least one surface of the piezoelectric element and supports the piezoelectric element, and the support member is fixed to the fixing member. Since the support member is laminated on at least one surface of the piezoelectric element, the piezoelectric element can be reinforced, thereby preventing the piezoelectric element from being broken.

  The support member is preferably made of a material that is softer than the piezoelectric element, thereby preventing external stress from being applied to the piezoelectric element. When the support member is made of a synthetic resin, the piezoelectric element is made of ceramics or quartz and is often made of a relatively hard material. Therefore, the piezoelectric element can be reinforced by the support member and also by an external force. The destruction of the piezoelectric element can be surely prevented.

  In the piezoelectric power generating device according to the present invention, preferably, the rotating body is an automobile tire, and therefore a piezoelectric power generating device in which a piezoelectric element, a fixing member, and a pressing member are arranged on an inner peripheral surface of the tire is configured. The In this case, the piezoelectric power generator of the present invention can be used as a power source for driving a sensor or the like for monitoring the air pressure of the tire disposed inside the tire.

  The piezoelectric power generation device according to the present invention is a piezoelectric power generation device that generates electric power by the piezoelectric effect with the rotation of a rotating body in which a flat portion is generated on the inner peripheral surface with rotation. And the said fixing member is being fixed to the internal peripheral surface of a rotary body, and the 1st end part of the piezoelectric element which generate | occur | produces electric power by a piezoelectric effect is fixed to this fixing member by expanding-contracting in a length direction. Yes. Further, the pressing member receives stress due to the deformation when the pressing member is deformed from the flat portion to the non-flat portion with the rotation of the rotating body, so that the second end portion of the piezoelectric element is compressed in the length direction. The second end of the piezoelectric element is pressed. Accordingly, when the rotating body rotates, a portion where the inner peripheral surface becomes flat appears periodically, and when the pressing member receives stress due to deformation when moving from the flat portion to a non-flat portion, the piezoelectric member Since the element is compressed in the length direction by the pressing member, and this compression deformation is repeatedly applied, electric power can be taken out by the piezoelectric effect.

  In the conventional piezoelectric power generation apparatus, electric power is taken out by utilizing the bending vibration of the piezoelectric element. Therefore, for example, when the power generation device is fixed to an automobile tire, as described above, when the tire gets on a stone or the like and the inner peripheral surface of the tire is deformed so as to be curved radially inward, the piezoelectric element is pulled. There was a possibility that the piezoelectric element was destroyed due to the stress.

  On the other hand, in the piezoelectric power generation device of the present invention, electric power is taken out by using expansion and contraction in the length direction of the piezoelectric device. In addition, the piezoelectric element is disposed on the surface side of the fixing member opposite to the inner peripheral surface of the rotating body, and the first end is fixed to the fixing member. Therefore, for example, even if the inner peripheral surface of the rotating body is deformed so as to be curved inward, stress due to such deformation is not easily applied to the piezoelectric element, and therefore, the piezoelectric element is not easily broken.

  Therefore, according to the present invention, it is possible to provide a piezoelectric power generation device that is unlikely to cause destruction of the piezoelectric element and that can reliably extract relatively large electric power.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  1A and 1B are diagrams for explaining a piezoelectric power generation device according to a first embodiment of the present invention. FIG. 1A is a diagram in which a piezoelectric element, a fixing member, and a pressing member are connected to each other. It is a perspective view which shows the structure currently performed, (b) is typical partial notch front sectional drawing of the piezoelectric generator of this embodiment.

  The piezoelectric power generation apparatus 1 according to the present embodiment includes an automobile tire 2 as a rotating body. The structural body 3 shown in FIG. 1A is fixed to the inner peripheral surface of the tire 2 as schematically shown in a region surrounded by a circle A in FIG. The part surrounded by the circle A will be described in more detail with reference to FIGS.

  2 shows a case where the structure 3 is located on the inner peripheral surface of the tire 2 in a portion where the tire 2 is grounded, and FIG. 3 shows that the tire 2 rotates and the structure 3 is the tire. It is a figure which shows the state in the middle of the part currently fixed to the internal peripheral surface of 2 from the flat part to the part which is not flat.

  That is, as shown in FIGS. 2 and 3, the tire 2 normally has a flat inner peripheral surface at a portion that is in contact with the road surface 4. Except for the grounded portion, the inner peripheral surface of the tire 2 is a substantially cylindrical curved surface, that is, a portion that is not flat.

  As shown in FIG. 1A, the structure 3 includes a fixing member 5, a piezoelectric element 6, a pressing member 7, and support members 8 and 9. The fixing member 5 is made of a rigid body such as metal and is fixed to the inner peripheral surface 2 a of the tire 2. The fixing member 5 includes a plate-like member 5a, a fixing wall 5b provided at one end of the plate-like member 5a, and a locking wall 5c provided on the opposite side of the fixing wall 5. The fixed wall 5b and the locking wall 5c are respectively extended from the plate-like member 5a in a direction away from the inner peripheral surface of the tire 2 as the rotating body. In the present embodiment, the inner surfaces of the fixed wall 5b and the locking wall 5c are extended in the direction perpendicular to the plate member 5a.

  The piezoelectric element 6 includes a rectangular plate-shaped piezoelectric body 10, a first electrode 11 stacked on the upper surface of the piezoelectric body 10, and a second electrode 12 formed on the lower surface of the piezoelectric body 9. The piezoelectric body 10 is made of a piezoelectric ceramic such as a lead zirconate titanate ceramic and is polarized in the thickness direction. The electrodes 11 and 12 can be formed of an appropriate metal or alloy.

  The piezoelectric element 6 is configured using a piezoelectric body 10 having a rectangular plate-like length direction. Therefore, the piezoelectric element 6 has a length direction, and one end in the length direction is the first end 6a, and the other end is the second end 6b. When the piezoelectric element 6 expands and contracts in the length direction, electric power is generated by the piezoelectric effect, and the generated electric power is taken out from the electrodes 11 and 12.

  The first end 6 a of the piezoelectric element 6 is fixed to the inner surface of the fixing wall 5 b of the fixing member 5.

  In the present embodiment, support members 8 and 9 made of synthetic resin are laminated on the piezoelectric element 6. The support members 8 and 9 are made of a material softer than the piezoelectric body constituting the piezoelectric element 6, and accordingly, when an external force other than stress for reinforcing the piezoelectric element 6 and expanding and contracting the piezoelectric element 6 is applied. In addition, the propagation of external force to the piezoelectric element 6 is suppressed. That is, since the external force is relieved by the support members 8 and 9, the piezoelectric element 6 is not easily broken.

  The material constituting the support members 8 and 9 is preferably a synthetic resin as described above, and when made of a synthetic resin, the synthetic resin is applied in a molten state on the upper and lower surfaces of the piezoelectric element 6 and cured, The supporting members 8 and 9 can be easily laminated on the piezoelectric element 6.

  However, the support members 8 and 9 can be made of an appropriate material that reinforces the piezoelectric element 6. A support member may be laminated only on one side of the piezoelectric element 6.

  In the present embodiment, the piezoelectric element 6 is disposed on the plate-like member 5 a of the fixing member 5 via the support member 9.

  The second end 6b of the piezoelectric element 6 is in a free end state.

  On the other hand, a gap is provided between the second end 6b and the locking wall 5c. The action wall 7b of the pressing member 7 is inserted into this gap.

  Like the fixing member 5, the pressing member 7 is made of a rigid body such as metal, and includes a plate-like member 7 a, a working wall 7 b, and a passive portion 7 c that comes into contact with the inner peripheral surface of the tire 2.

  That is, the lower end of the passive portion 7 c is in contact with the inner peripheral surface 2 a of the tire 2. The plate-like member 7a extends from the upper end of the passive portion 7c to the piezoelectric element 6 side. The end of the plate-like member 7 on the piezoelectric element 6 side is provided with a working wall 7 b extending in the gap between the aforementioned locking wall 5 c and the second end 6 b of the piezoelectric element 6. .

  As described above, the pressing member 7 extends outward in the length direction of the piezoelectric element 6 in the length direction of the piezoelectric element 6.

  Note that the outer end surface of the working wall 7 b is in contact with the second end 6 b of the piezoelectric element 6. However, the outer end face of the working wall 7b may be arranged with a slight gap from the second end 6b of the piezoelectric element 6.

  Next, with reference to FIG.2 and FIG.3, operation | movement of the piezoelectric generator 1 of this embodiment is demonstrated.

  When the structure 3 of the piezoelectric generator 1 is located on the inner peripheral surface of the tire 2 in a portion corresponding to the portion of the tire 2 that is in contact with the road surface 4, the state shown in FIG. 2 is obtained. . Here, the structure 3 is located in a flattened portion of the inner peripheral surface of the tire 2. Therefore, the pressing member 7 is positioned in the longitudinal direction of the piezoelectric element 6, and the pressing force from the pressing member 7 does not act on the piezoelectric element 6.

  On the other hand, the portion of the tire 2 that rotates and contacts the road surface 4 changes sequentially. In this case, the inner peripheral surface of the tire 2 has a cylindrical curved shape other than the grounded portion. That is, as shown in FIG. 3, the inner peripheral surface of the tire 2 is a cylindrical curved surface, and in the case of a non-flat portion, the passive portion 7 c of the pressing member 7 is piezoelectric by the inner peripheral surface of the tire 2. The element 6 is moved more inwardly of the tire 2 than the lengthwise extension line of the element 6. Due to the deformation of the tire 2, the stress acts on the passive portion 7 c of the pressing member 7, and the plate-like member 7 a of the pressing member 7 is against the extension in the length direction of the piezoelectric element 6 as shown in FIG. 3. Will be inclined. Then, the action wall 7b rotates in the clockwise direction with the action wall 7b positioned on the opposite side of the passive part 7c of the plate-like member 7 as the fulcrum. As a result, the outer end surface of the working wall 7b presses the second end 6b of the piezoelectric element 6 and compresses the piezoelectric element 6 in the length direction.

  In this case, stress due to deformation of the inner peripheral surface of the tire 2 is applied to the passive portion 7 c of the pressing member 7, and the passive portion 7 c serves as a power point, and the action wall 7 b of the pressing member 7 and the locking wall 5 c of the fixing member 5. The portion in contact with becomes a fulcrum, and the outer end face of the action wall 7b becomes the action point. Since the distance between the fulcrum and the fulcrum is shorter than the distance between the force point and the fulcrum, a large force is applied to the piezoelectric element 6 from the end face of the action wall 7b by the action of the insulator.

  Therefore, the piezoelectric element 6 is compressed with a large force in the length direction. While the tire 2 rotates, the state in which the compressive stress is applied to the piezoelectric element 6 and the state in which the compressive stress is released in the grounded portion are periodically repeated. Will periodically expand and contract in the length direction. Therefore, electric power can be taken out from the piezoelectric element 6 by the piezoelectric effect.

  In the piezoelectric power generation apparatus 1 of the present embodiment, as described above, electric power is extracted by using the expansion and contraction of the piezoelectric element 6 in the length direction. As described above, in the structure in which electric power is extracted from the piezoelectric element using the conventional bending vibration, when the tire rides on a stone, the inner peripheral surface of the tire is curved radially inward, and tensile stress is applied to the piezoelectric element. In addition, the piezoelectric element may be destroyed.

  On the other hand, the piezoelectric power generation apparatus 1 according to the present embodiment uses the expansion and contraction of the piezoelectric element 6 in the length direction and does not bend and deform the piezoelectric element 6. Accordingly, the piezoelectric element 6 is essentially not easily broken. In addition, the piezoelectric element 6 is not directly fixed to the inner peripheral surface of the tire 2 but is fixed to the fixing member 5. Therefore, even if the tire 2 rides on a stone, for example, and the inner peripheral surface of the tire 2 is curved inward, the piezoelectric element 6 is not directly subjected to the stress due to the curvature of the inner peripheral surface of the tire 2, so that the piezoelectric element 6 is destroyed. Is unlikely to occur.

  Moreover, even if the portion where the tire 2 is curved inward by climbing on the stone is positioned on the pressing member 7 side on the left side of the fixing member 5 in the structure of FIG. 1A, for example, The pressing member 7 rotates clockwise around the fulcrum described above. Therefore, as in the case shown in FIG. 3, only the force for suppressing the piezoelectric element 6 acts, and the piezoelectric element 6 can be reliably expanded and contracted while preventing the piezoelectric element 6 from being destroyed. Further, when the tire 2 rides on a stone and the inner peripheral surface 2a of the tire 2 is curved inward at a portion where the fixing member 5 and the pressing member 7 are connected, what is shown in FIG. In contrast, the fulcrum moves above the locking wall 5c, but even in that case, the piezoelectric element 6 is compressed in the length direction by the lower portion of the action wall 7b of the pressing member 7. Therefore, the piezoelectric element 6 can be reliably expanded and contracted while preventing the piezoelectric element 6 from being broken.

  FIG. 4 is a schematic perspective view for explaining a piezoelectric power generator according to a second embodiment of the present invention. In the piezoelectric power generation device of the second embodiment, the structure 21 shown in FIG. 4 is fixed to the inner peripheral surface of the rotating body.

  The structure 21 includes a fixing member 22, a piezoelectric element 23, support members 24 and 25, and a pressing member 26. However, in this embodiment, the fixing member 22 and the pressing member 26 are integrally formed of the same material.

  In the present embodiment, the fixing member 22 has a first plate-like member 22a. A fixed wall 22b is provided on one end side of the first plate-like member 22a. The piezoelectric element 23 has a first end 23a at one end in the length direction fixed to the inner surface of the fixed wall 22b. The piezoelectric element 23 is configured similarly to the piezoelectric element 6 of the first embodiment.

  The second end 23b, which is the other end in the length direction of the piezoelectric element 23, is a free end.

  Support members 24 and 25 are laminated on both surfaces of the piezoelectric element 23. The support members 24 and 25 are configured similarly to the support members 7 and 8 of the first embodiment.

  On the other hand, the fixing member 22 is integrally formed by a pressing member 26 and a rigid body such as a metal, and a thin portion 27 is provided at a boundary portion between them. The fixing member 22 is connected to one side of the thin portion 27 and the pressing member 26 is connected to the other side. The pressing member 26 includes a second plate-like member 26a and a working wall 26b. Here, the action wall 26 b extends from the second plate-like member 26 a to the inside of the rotating body, and one end surface of the action wall 26 b is in contact with the second end 23 b of the piezoelectric element 23. But the one end surface of the action wall 26b may be arrange | positioned through the 2nd end part 23b of the piezoelectric element 23, and the clearance gap.

  The second plate-like member 26 a is disposed on the same plane as the first plate-like member 22 a and is connected via the thin portion 27. The thin portion 27 is provided by forming a groove extending in a direction orthogonal to the length direction of the piezoelectric element 23 from both surfaces of such a plate-like member. This groove may be formed only on one surface of the plate-like member.

  Also in this embodiment, the pressing member 26 is located on the outer side in the length direction of the piezoelectric element 23. And as shown in FIG. 5, the plate-shaped member 22a of the said fixing member 22 is being fixed to the internal peripheral surface of the tire 2 as a rotary body. The second plate member 26a is in contact with the inner peripheral surface of the tire 2, but is not fixed. .

  Also in this embodiment, when the structure 21 is in contact with the road surface 4 of the tire 2 and the inner peripheral surface is located at a flat portion, the piezoelectric element 23 has a compressive stress. Don't join.

  On the other hand, when the structural body 21 is located in a non-flat portion of the inner peripheral surface of the tire 2, as shown in FIG. 5, it is opposite to the piezoelectric element 23 of the second plate member 26a of the pressing member 26. The end portion on the side moves toward the inner side of the tire 2. Therefore, when the force accompanying the deformation of the tire 2 is applied to the end portion of the second plate-like member 26a of the pressing member 26 opposite to the piezoelectric element 23, the thin portion 27 serves as a fulcrum and the pressing member 26 Rotates clockwise in FIG. 5 around the thin wall portion. Along with this rotational displacement, the working wall 26b also rotates clockwise around the thin portion 27, and one surface of the working wall 26b presses the piezoelectric element 23 in the length direction.

  That is, the thin portion 27 serves as a fulcrum, the end of the second plate member 26a opposite to the piezoelectric element 23 serves as a power point, and the action point serves as the second end 23b of the piezoelectric element 23 of the working wall 26b. The pressing force acts on the piezoelectric element 23 in contact with the piezoelectric element 23. In this case, the distance between the force point and the fulcrum is made larger than the distance between the fulcrum and the action point.

  Therefore, also in this embodiment, a large compressive stress is applied to the piezoelectric element 23 by the action of the insulator.

  As in the case of the first embodiment, when the tire 2 rotates, the flat portion and the non-flat portion of the inner peripheral surface of the tire 2 appear periodically. Therefore, also in this embodiment, the state in which the piezoelectric element 23 is compressed in the length direction and the state in which the compressive stress is released are repeated, and electric power is extracted by the piezoelectric effect. Also in this embodiment, since the piezoelectric element 23 does not utilize bending deformation, it is difficult to cause breakage due to deformation. In addition, even if the tire rides on a stone and the inner peripheral surface of the tire 2 is deformed so as to protrude inward, the piezoelectric element 23 is fixed via the fixing member 22, so that the piezoelectric element 6 is deformed. hard. Therefore, the piezoelectric element 23 is hardly damaged. In the second embodiment, by providing the thin portion 27, the pressing member 26 is easily moved with respect to the fixed member 22 using the thin portion 27 as a fulcrum. Instead of the thin-walled portion 27, the pressing member 26 may be connected to the fixing member 22 by an appropriate mechanism that is rotatably connected, such as a hinge or a hinge.

  FIG. 6 is a front view showing a modification of the piezoelectric power generation device 3 of the first embodiment. In the piezoelectric power generation device 3 of the first embodiment, the piezoelectric element 6 is fixed to the fixing member 5, and the pressing member 7 is connected to the fixing member 5. On the other hand, in the piezoelectric power generation apparatus 41 of the modified example shown in FIG. 6, the piezoelectric element 6 </ b> A is also fixed to the pressing member 42. That is, the pressing member 42 and the piezoelectric element 6 </ b> A have the same structure as the fixing member 5 and the piezoelectric element 6. Similar to the pressing member 7, the pressing member 42 is made of a rigid body such as metal, and includes a plate-shaped member 42 a, a working wall 42 b, and a passive portion 42 c that is mounted on the inner peripheral surface of the tire 2. The piezoelectric element 6A is fixed between the working wall 42b and the passive portion 42c.

  As described above, the piezoelectric element 6A may be provided also on the pressing member 42 side. Therefore, in the piezoelectric power generation device 41 of the present modification, when the tire rotates, not only the stretching stress is repeatedly applied to the piezoelectric element 6, Stretching stress is repeatedly applied to the piezoelectric element 6A. That is, the locking wall 5c of the fixing member 5 also acts as an action wall that expands and contracts the piezoelectric element 6A in the length direction. Therefore, not only the piezoelectric element 6 but also the piezoelectric element 6A can take out the electric power accompanying the expansion / contraction by the piezoelectric effect, and can take out a larger electric power.

  FIG. 7 is a front view showing a piezoelectric power generating device according to another modification of the piezoelectric power generating device 3 of the first embodiment. The piezoelectric power generation device 51 includes a fixing member 5 to which the piezoelectric element 6 is fixed and a pressing member 7 as in the first embodiment. Accordingly, the basic structure is the same as that of the piezoelectric power generation device 3 of the first embodiment.

  However, in the piezoelectric power generation device 51, the piezoelectric power generation device 3 of the first embodiment is disposed upside down so that the plate-like member 7a of the pressing member 7 is in contact with the inner peripheral surface of the tire. In this case, the plate-like member 7a of the pressing member 7 is fixed to the inner peripheral surface of the tire, but when a flat portion appears periodically on the inner peripheral surface of the tire, the pressing is performed as in the case of the first embodiment. The force acts repeatedly so that the piezoelectric element 6 is compressed in the length direction by the outer surface of the working wall 7 b of the member 7, whereby electric power can be extracted from the piezoelectric element 6 by the piezoelectric effect.

  In this modification, among the support members stacked above and below the piezoelectric element 6, the support member 9 a stacked on the fixed member 5 side has the same lengthwise dimension as the piezoelectric element 6 and the support member 8. Therefore, a gap X is formed between one end of the support member 9 </ b> A and the pressing member 7. Thus, the gap X may be formed between the support member 9A and the locking wall 5c of the fixing member 5. Such a structure can be formed by previously forming a laminated body in which the supporting members 8 and 9A are laminated on the upper and lower sides of the piezoelectric element 6 and then bonding the laminated body to the plate-like member 5a of the fixing member 5. it can.

  Of course, in this modified example, as in the case of the first embodiment, instead of the support member 9A, the support member 9 without the gap X may be used. In that case, after applying the adhesive which comprises the supporting member 9 to the fixing member 5, it can manufacture by the method of laminating | stacking the piezoelectric element 6 and bonding together.

  FIG. 8 is a front view for explaining still another modified example of the piezoelectric power generation device 3 of the first embodiment.

  In the piezoelectric power generation device 3 of the first embodiment, the pressing member 7 is provided only on one side of the fixing member 5, but also on the other side of the fixing member 5 as in the piezoelectric power generation device 61 shown in FIG. 8. The pressing member 7 may be provided. In that case, the piezoelectric element 6 is expanded and contracted by the relative movement of the pressing members 7 on both sides with respect to the fixing member 5, so that even larger electric power can be taken out.

  In the first and second embodiments, the tire 2 is shown as the rotating body. However, the piezoelectric power generation device of the present invention is not limited to the tire 2, and a portion that becomes flat on the inner peripheral surface with rotation is provided. A piezoelectric power generator can be configured using various rotating bodies that are generated periodically.

BRIEF DESCRIPTION OF THE DRAWINGS (a) is a perspective view which shows the principal part of the piezoelectric power generator concerning the 1st Embodiment of this invention, (b) is the schematic partial notch front for demonstrating the piezoelectric power generator of 1st Embodiment. Sectional drawing. The partial notch front sectional view which shows the state which is not receiving the stress which the piezoelectric element compresses to a length direction in the piezoelectric power generator of 1st Embodiment. FIG. 4 is a partially cutaway front cross-sectional view for explaining a state in which the piezoelectric element is compressed in the length direction under stress when the inner peripheral surface of the tire is deformed in the piezoelectric power generation device of the first embodiment. The perspective view which shows the principal part of the piezoelectric power generator which concerns on the 2nd Embodiment of this invention. In the piezoelectric generator of 2nd Embodiment, when the internal peripheral surface of a tire deform | transforms, the partial notch front sectional drawing which shows the state in which a piezoelectric element is compressed to a length direction. The front view which shows the piezoelectric power generator which concerns on the modification of the 1st Embodiment of this invention. The front view which shows the further another modification of the piezoelectric power generator of 1st Embodiment. The front view which shows the piezoelectric power generator which concerns on the further another modification of the 1st Embodiment of this invention. (A) is a typical front view for demonstrating an example of the conventional piezoelectric generator, (b) and (c) are the states in which the piezoelectric element is not receiving the stress in the conventional piezoelectric generator, respectively. And each typical partial notch front sectional drawing which shows the state which receives the stress and is carrying out the bending deformation. In the conventional piezoelectric generator, the partial notch front sectional drawing for demonstrating a problem at the time of deform | transforming so that the internal peripheral surface of a tire may curve inside.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric generator 2 ... Tire 3 ... Structure 4 ... Road surface 5 ... Fixed member 5a ... Plate-like member 5b ... Fixed wall 5c ... Locking wall 6 ... Piezoelectric element 7 ... Pressing member 7a ... 2nd plate-like member 7b ... Working wall 7c ... Passive part 8,9 ... Support member 10 ... Piezoelectric body 11,12 ... Electrode 21 ... Structure 22 ... Fixing member 22a ... First plate member 22b ... Fixing wall 23 ... Piezoelectric element 24,25 ... Support member 26 ... Pressing member 26a ... Second plate-like member 26b ... Working wall 27 ... Thin wall portion 41 ... Piezoelectric generator 42 ... Pressing member 6A ... Piezoelectric element 42a ... Plate-like member 42b ... Working wall 42c ... Passive portion 51 ... Piezoelectric generator 9A ... support member 61 ... piezoelectric generator

Claims (9)

A piezoelectric power generation device that generates electric power by a piezoelectric effect as the rotating body rotates,
A rotating body in which a flat portion is generated on the inner peripheral surface with rotation,
One end in the length direction is the first end, the other end in the length direction is the second end, and by expanding and contracting in the length direction, a piezoelectric element that generates power by the piezoelectric effect;
A fixing member that is fixed to the inner peripheral surface of the rotating body and to which the first end of the piezoelectric body is fixed;
The piezoelectric element is disposed outside the second end portion, and receives the stress due to the deformation when the inner peripheral surface of the rotating body is deformed from a flat portion to a non-flat portion with the rotation of the rotating body, And a pressing member that presses the second end of the piezoelectric element so as to compress the piezoelectric element in a length direction in accordance with a stress caused by the deformation.   The pressing member is located on the outer side in the longitudinal direction of the piezoelectric body from the second end of the piezoelectric element, and when stress due to deformation of the inner peripheral surface of the rotating body is applied, the pressing member The end of the pressing member opposite to the piezoelectric element moves toward the inner side of the rotating body relative to the end of the pressing member on the piezoelectric element side, and the end of the pressing member on the piezoelectric element side of the piezoelectric member The piezoelectric power generation device according to claim 1, wherein the piezoelectric power generation device presses the second end portion. The fixing member extends in a direction away from the inner peripheral surface of the rotating body from the plate-shaped member fixed to the inner peripheral surface of the rotating body and the first end portion side of the piezoelectric element of the plate-shaped member. And the fixed wall to which the first end of the piezoelectric element is fixed and the fixed wall of the plate-like member are on the opposite side in the length direction of the piezoelectric element, and the piezoelectric element A locking wall that is located outside the second end and is provided to extend in a direction away from the inner peripheral surface of the rotating body;
The pressing member has a working wall inserted between the inner surface of the locking wall and the second end of the piezoelectric element, and the surface of the working wall on the piezoelectric element side is the piezoelectric element. The piezoelectric power generation device according to claim 2, wherein the second end of the piezoelectric power generation device is pressed.   The pressing member is integrally connected to the fixing member, and a thin portion is provided for facilitating displacement of the pressing member with respect to the fixing member at a boundary portion between the fixing member and the pressing member. The piezoelectric power generation device according to claim 2. A first plate member fixed to the inner peripheral surface of the rotating body;
A fixing wall provided to extend in a direction away from the inner peripheral surface of the rotating body on the first end side of the piezoelectric element of the plate-like member, and the first wall of the piezoelectric element is provided on the fixing wall. The end of is fixed,
A second plate-like member provided so that the pressing member extends along an inner peripheral surface of the rotating body; and the second rotating member on the second end side of the piezoelectric element of the second plate-like member. A working wall provided in a direction away from the inner peripheral surface of the rotating member, and an end of the pressing member opposite to the piezoelectric element is caused by stress due to deformation of the inner peripheral surface of the rotating member. 5. The piezoelectric power generation device according to claim 4, wherein the piezoelectric power generation device is configured to move in an inward direction, whereby the second end portion of the piezoelectric element is pressed by the working wall.   6. The piezoelectric element according to claim 1, further comprising a support member that is laminated on at least one surface of the piezoelectric element and that supports the piezoelectric element, and the support member is fixed to the fixing member. The piezoelectric power generation device described.   The piezoelectric power generation device according to claim 6, wherein the support member is made of a material softer than the piezoelectric element.   The piezoelectric power generation device according to claim 7, wherein the support member is made of a synthetic resin. The piezoelectric device according to claim 1, wherein the rotating body is an automobile tire, and the piezoelectric element, the fixing member, and the pressing member are disposed on an inner peripheral surface of the tire. Power generation device.

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