Infinite rotator

Abstract

This infinite rotator comprises: a rim part; a hub attachment part; and a plurality of spokes that connect the rim part and the hub attachment part. Piezoelectric elements are arranged on the spokes.

Description

Infinite rotating body 【0001】 This disclosure relates to infinite rotating bodies such as tire wheels. 【0002】 There is a technique of arranging piezoelectric elements on tires, wheels, etc. For example, Patent Document 1 describes attaching a piezoelectric sensor to the outer peripheral surface of the rim portion of a wheel. Patent Document 2 describes providing a coating-type piezoelectric portion on the back surface of the grounding portion of a tire. 【0003】 Japanese Unexamined Patent Application Publication No. 2007 - 163230, Japanese Unexamined Patent Application Publication No. 2022 - 47625 【0004】 Although Patent Document 1 describes the idea of arranging a piezoelectric sensor on the outer peripheral surface of the rim portion, the outer peripheral surface of the rim portion of a wheel that has been put into practical use has a complex shape. Further technical consideration is required regarding at what position it is best to arrange the piezoelectric element in accordance with such a complex shape of the outer peripheral surface of the rim portion. 【0005】 The technique of Patent Document 2 generates electric power according to the strain generated on the grounding surface of the tire. Therefore, there is a risk that the piezoelectric portion arranged on the back surface of the grounding portion of the tire will be damaged while the tire is repeatedly deformed. 【0006】 In one aspect, an infinite rotating body is provided. The infinite rotating body includes a rim portion, a hub attachment portion, and a plurality of spokes connecting the rim portion and the hub attachment portion, and a piezoelectric element is arranged on each spoke. 【0007】 FIG. 1 is a perspective view seen from the outer side in the vehicle width direction of a vehicle wheel in one embodiment. FIG. 2 is a perspective view seen from the inner side in the vehicle width direction of the vehicle wheel of FIG. 1. FIG. 3 is a diagram showing the stress distribution on the outer side surface in the vehicle width direction of the vehicle wheel of FIG. 1. FIG. 4 is a diagram showing the stress distribution on the inner side surface in the vehicle width direction of the vehicle wheel of FIG. 1. FIG. 5 is a characteristic diagram showing the relationship between elapsed time and voltage when a piezoelectric element is arranged on the inner surface of the inner bead seat portion. FIG. 6 is a characteristic diagram showing the relationship between elapsed time and voltage when a piezoelectric element is arranged on the inner surface of the root portion of the spoke portion. 【0008】Hereinafter, a vehicle wheel to which the infinitely rotating body according to this disclosure is applied will be described with reference to the drawings. <Overall configuration of the wheel> As shown in Figures 1 and 2, the vehicle wheel 10 according to this embodiment is a wheel used in passenger cars and the like. This wheel is made of aluminum, i.e., an aluminum wheel, and is a one-piece wheel made by casting. Such a wheel 10 comprises a substantially cylindrical rim portion 11 to which a pneumatic tire is attached, a hub mounting portion 12, and a plurality of spokes 13 that extend radially from the hub mounting portion 12 toward the rim portion 11. 【0009】 The rim portion 11 includes an inner flange portion 15, an inner bead seat portion 16, a drop portion 17, an outer bead seat portion 18, and an outer flange portion 19. In Figures 1 and 2, the inner side in the vehicle width direction, i.e., the side closer to the inside of the vehicle, is indicated as "in" when the wheel 10 is mounted on a vehicle, and the outer side in the vehicle width direction is indicated as "out". When the wheel 10 is mounted on a vehicle, the inner flange portion 15 and the inner bead seat portion 16 are located inward in the vehicle width direction, i.e., closer to the inside of the vehicle, than the outer bead seat portion 18 and the outer flange portion 19. 【0010】 The hub mounting portion 12 includes a hub hole 21 formed in its center and a plurality of bolt holes 22 arranged around the hub hole 21. Each spoke 13 is configured to connect the rim portion 11 and the hub mounting portion 12. Multiple spokes 13 are formed at intervals in the circumferential direction when viewed from the outside in the vehicle width direction. Between each pair of adjacent spokes 13 in the circumferential direction, an opening 23 is provided that connects the space on the outside in the vehicle width direction with the space on the inside in the vehicle width direction. The opening 23 is, for example, a decorative hole. In this embodiment, five pairs of spokes 13, each formed with a first interval 24a, are provided with a second interval 24b that is wider than the first interval 24a. 【0011】Incidentally, the inner surface of the wheel 10 in the vehicle width direction is the mounting surface 13a to the vehicle. Therefore, the inner surface of the spoke 13 is relatively flat. In contrast, the outer surface of the wheel 10 in the vehicle width direction is the design surface 13b. Therefore, the outer surface of the spoke 13 has a complex shape composed of various shapes of bumps and indentations. 【0012】 Furthermore, the thickness of the rim portion 11 of an aluminum wheel is generally thicker than that of a steel wheel. And, in each spoke 13, the position closer to the rim portion 11 has higher rigidity than the position closer to the hub mounting portion 12 than the position closer to the hub mounting portion 12. Therefore, stress concentrates as you approach the base of the spoke 13. 【0013】 <Piezoelectric Element> On each spoke 13, a piezoelectric element 26, which is a power generation element, is attached to the mounting surface 13a, which is the inner surface. Within the mounting surface 13a, the piezoelectric element 26 is positioned in a region with higher stress than other regions. For example, the piezoelectric element 26 is positioned on the mounting surface 13a of the spoke 13, closer to the hub mounting portion 12 than to the rim portion 11. For example, the piezoelectric element 26 is positioned at the base of the spoke 13. The mounting surface 13a may be an inclined surface as an example, but it is preferable that it be a flat surface so that the piezoelectric element 26 can be stably positioned. Of course, the mounting surface 13a may have some irregularities, but it is preferable that it be flatter than the design surface 13b. By positioning the piezoelectric element 26 on the mounting surface 13a, it can be made less visible from the outside in the vehicle width direction. 【0014】 Here, Figure 3 shows the stress distribution as seen from the outer surface of the wheel 10 when a vehicle load is applied to the wheel 10. Figure 4 shows the stress distribution as seen from the inner surface of the wheel 10 when a vehicle load is applied to the wheel 10. Darker colors indicate higher stress levels. 【0015】In Figures 3 and 4, it can be seen that the stress on the spokes 13 is higher at the base portion closer to the hub mounting portion 12 than on the rim portion 11, both on the inner and outer surfaces of the spokes 13. Furthermore, it can be seen that the stress tends to be higher on the inner surface of the spokes 13 than on the outer surface of the wheel 10. 【0016】 The piezoelectric element 26 is a piezoelectric element that generates voltage when pressure is applied. The piezoelectric element 26 is, for example, a piezoelectric material. When pressure is applied to the piezoelectric material, strain occurs, and a voltage is generated in accordance with this strain. The piezoelectric material is, for example, formed by thin film formation. Inorganic piezoelectric materials and organic piezoelectric materials are selected and used as piezoelectric materials depending on the placement location and other factors. Inorganic piezoelectric materials have poor flexibility because they are mainly composed of ceramics, but have high power generation efficiency. Organic piezoelectric materials have excellent flexibility but low power generation efficiency. The type of piezoelectric element 26 is selected according to conditions such as the shape of the place where it is placed. Furthermore, the piezoelectric elements 26 placed on each spoke 13 are the same, and their shape and output are the same. 【0017】 The piezoelectric elements 26 arranged on the spokes 13 are separate and discontinuous. By intermittently arranging multiple piezoelectric elements 26 at equal intervals, it is possible to suppress the cancellation of outputs between adjacent piezoelectric elements 26. 【0018】 The piezoelectric element 26, positioned on the mounting surface 13a of the spoke 13, at the base portion closer to the hub mounting portion than the rim portion 11, can obtain an output voltage with the same period. When the output voltage of the piezoelectric element 26 increases, the output current also increases accordingly, thereby increasing the generated power (generation efficiency). 【0019】 Here, the output voltage was examined when piezoelectric elements 26 were placed on the inner surface in the vehicle width direction of the inner bead seat portion 16 (point A in Figure 2) and on the inner surface in the vehicle width direction of the base portion of the spoke 13 (point B in Figure 2) in the wheel 10 shown in Figures 1 to 4. Figure 5 shows the output voltage of the piezoelectric element 26 placed on the inner surface of the inner bead seat portion 16, and Figure 6 shows the output voltage of the piezoelectric element 26 placed on the inner surface of the base portion of the spoke 13. In Figures 5 and 6, the vertical and horizontal axis scales are the same. 【0020】 <Measurement Conditions> - Aluminum wheel for passenger car - Wheel / tire: 18 x 8J / 225 / 45R18 - Air pressure: 240 kPa - Test load: 6.15 kN - Test speed: 20 km / h From Figures 5 and 6, it can be confirmed that the inner surface of the base of the spoke 13 can obtain a higher output voltage than the inner surface of the inner bead seat portion 16. This is because the stress is higher on the inner surface of the base of the spoke 13 than on the inner surface of the inner bead seat portion 16. 【0021】 The electricity generated by the piezoelectric element 26 is stored in a secondary battery, such as a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The secondary battery is, for example, an automotive battery and is located on the chassis. In this case, the electricity generated by the piezoelectric element 26 is stored in the secondary battery located on the chassis and used as part of the vehicle's power. Alternatively, the secondary battery may be located on the wheel 10. For example, the wheel 10 may have light-emitting elements such as LEDs for illumination. The wheel 10 may also have detection elements such as sensors for detecting abnormalities in the connection with the hub. These elements, as well as communication elements for exchanging detection data and control data with other communication devices, are powered by the secondary battery located on the wheel 10. 【0022】 <Effects of the Embodiment> The wheel 10 described above can obtain the following effects: (1) The piezoelectric element 26 for power generation is less prone to failure when placed on the wheel 10 than when it is placed on the tire. 【0023】(2) The spokes 13 are locations where stress is concentrated more than in other parts. Therefore, by placing the piezoelectric element 26 on the spokes 13, the power generation efficiency of the piezoelectric element 26 can be increased. In particular, on each spoke 13, stress is concentrated more at the position closer to the hub mounting portion 12 than to the rim portion 11 than at the position closer to the rim portion 11 than to the hub mounting portion 12. Therefore, by placing the piezoelectric element 26 on the spokes 13 at a position closer to the hub mounting portion 12 than to the rim portion 11, the power generation efficiency of the piezoelectric element 26 can be further increased. 【0024】 (3) By arranging the piezoelectric element 26 on the mounting surface 13a, which is the inner surface of the spoke 13 in the vehicle width direction, the piezoelectric element 26 can be made less visible from the outside in the vehicle width direction. (4) Since the piezoelectric element 26 is arranged on the mounting surface 13a of the spoke 13, wiring to the secondary battery becomes easier. For example, if the piezoelectric element 26 is arranged on the outer surface of the rim portion 11, a through hole or the like connected to the inner circumference of the rim portion 11 will be necessary for wiring. In this respect, if the piezoelectric element 26 is arranged on the mounting surface 13a, which is the inner surface of the spoke 13 in the vehicle width direction, it becomes unnecessary to provide a through hole for wiring in the rim portion 11, whether the secondary battery is located in the vehicle or in the inner space of the wheel 10. 【0025】 (5) The mounting surface 13a, which is the inner surface, is flatter than the outer surface of the spoke 13 in the vehicle width direction, which is the design surface 13b. Therefore, the piezoelectric element 26 can be stably arranged within the mounting surface 13a. In addition, an inorganic piezoelectric material, which has poor flexibility but high power generation efficiency, can be used as the piezoelectric element 26. 【0026】 (6) Piezoelectric elements can also be placed on aluminum wheels. The vehicle wheel 10 can also be further modified as appropriate as follows. 【0027】 The metal of the wheel 10 may be steel. That is, the wheel 10 may be made of steel. Alternatively, the wheel 10 may be made of titanium alloy, magnesium alloy, etc. 【0028】 - The mounting surface 13a of the spoke 13 may have irregularities. - Piezoelectric elements do not have to be placed on all spokes 13. That is, piezoelectric elements may be placed on some of the spokes 13, and not on the rest. 【0029】 The piezoelectric element 26 may be positioned on the mounting surface 13a of the spoke 13, closer to the rim portion 11 than the hub mounting portion 12, or at an intermediate position. Furthermore, the piezoelectric element 26 may be positioned over almost the entire mounting surface 13a. 【0030】 The piezoelectric element 26 may be placed only on the design surface 13b in addition to the mounting surface 13a of the spoke 13, or it may be placed on both the mounting surface 13a and the design surface 13b. For example, even if it is placed on the outer surface in the vehicle width direction at the base of the spoke 13, almost the same power generation efficiency can be obtained. Within the design surface 13b, the piezoelectric element 26 can be stably positioned on any flat surface. 【0031】 Furthermore, after arranging the piezoelectric elements 26 on the spokes 13, the piezoelectric elements 26 may also be arranged on the outer or inner circumferential surface of the rim portion 11. When the piezoelectric elements 26 are arranged on the rim portion 11, it is preferable to arrange them on the drop portion 17. 【0032】 - In the case of aluminum wheels, they may consist of two parts: a rim section and a disc section equipped with a hub mounting section and spokes. In this case, the rim section and the disc section are joined by bolts and nuts, welding, etc. Furthermore, the rim section may be divided in the axle direction and consist of three parts. 【0033】 Furthermore, aluminum wheels are cast wheels, forged wheels formed by press drawing from steel sheets, or forged aluminum wheels formed from bullets or castings. • Infinitely rotating bodies are not limited to large wheels used in commercial vehicles, etc. For example, they can also be applied to wheels for passenger cars, work vehicles, bicycles, and railway wheels.

Claims

1. An infinitely rotating body comprising a rim portion, a hub mounting portion, and a plurality of spokes connecting the rim portion and the hub mounting portion, wherein a piezoelectric element is disposed on each spoke.

2. The infinitely rotating body according to claim 1, wherein the piezoelectric element is arranged on the inner surface of the spoke in the vehicle width direction.

3. The infinitely rotating body according to claim 1 or 2, wherein the piezoelectric element is positioned in the spoke closer to the hub mounting portion than to the rim portion.

4. The infinitely rotating body according to claim 1, wherein the inner surface of the spoke in the vehicle width direction is flatter than the outer surface of the spoke in the vehicle width direction.

5. The infinitely rotating body according to claim 1, which is made of aluminum.

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