Wheel and state determination device

Abstract

To provide a wheel capable of detecting a deviation in wheel balance in a state where the wheel is attached to a vehicle.SOLUTION: The wheel has: a rim portion; a plurality of first measurement areas defined in the rim portion at regular intervals in a circumferential direction; a first strain gauge arranged in each of the first measurement areas; a first bridge circuit provided for each of the first strain gauges arranged in the respective first measurement areas to generate a first strain waveform in each of the first measurement areas on the basis of a change in resistance value of the first strain gauge; and a wireless transmitting unit for transmitting information based on the first strain waveform to the outside of the rim portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wheel and a state determination device. [Background technology]

[0002] There is known a technology for providing a strain gauge on a tire or wheel for a vehicle to detect the condition of the tire or wheel. One example is an annular support ring that is attached to a wheel rim within the tire cavity surrounded by the tire and the wheel rim on which the tire is mounted, and that abuts against the inner surface of the tread portion to support the load when the internal pressure of the tire drops. A strain gauge is fixed to this support ring, and the strain gauge changes its own electrical resistance by deforming together with the support ring. Based on this change in electrical resistance, the drop in the internal pressure of the tire can be detected (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-7928 A Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, wheel balance is usually checked with the tires and wheels removed from the vehicle, but it would be more useful if the wheel balance could be checked with the tires and wheels installed on the vehicle.

[0005] An object of the present invention is to provide a wheel capable of detecting a deviation in wheel balance while the wheel is mounted on a vehicle. [Means for solving the problem]

[0006] The wheel has a rim portion, a plurality of first measurement areas defined in the rim portion at regular intervals in the circumferential direction, a first strain gauge arranged in each of the first measurement areas, a first bridge circuit provided for each of the first strain gauges arranged in the first measurement areas and generating a first strain waveform in each of the first measurement areas based on changes in the resistance value of the first strain gauge, and a wireless transmitting unit that transmits information based on the first strain waveform to outside the rim portion. Effect of the Invention

[0007] According to the disclosed technology, it is possible to provide a wheel that is capable of detecting a deviation in wheel balance while mounted on a vehicle. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a wheel according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a circuit block of the wheel according to the first embodiment. [Diagram 3] FIG. 2 is a diagram illustrating an example of a bridge circuit. [Figure 4] FIG. 2 is an example of a hardware block diagram of a control unit. [Diagram 5] FIG. 2 is a plan view illustrating the strain gauge according to the first embodiment. [Figure 6] 1 is a cross-sectional view (part 1) illustrating a strain gauge according to a first embodiment. FIG. [Figure 7] 4 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. FIG. [Figure 8] 1A to 1C are diagrams illustrating a wheel according to a first modified example of the first embodiment. [Figure 9] 10A and 10B are diagrams illustrating a wheel according to a second modified example of the first embodiment. [Figure 10] 13A to 13C are diagrams illustrating a wheel according to a third modified example of the first embodiment. [Figure 11] 13 is a partially enlarged side view illustrating a wheel according to a fourth modified example of the first embodiment. FIG. [Figure 12] FIG. 13 is a partially enlarged side view illustrating a wheel according to a fifth modified example of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are designated by the same reference numerals, and duplicated explanations may be omitted.

[0010] First embodiment Fig. 1 is a diagram illustrating a wheel according to a first embodiment. In detail, Fig. 1(a) is a front view, Fig. 1(b) is a cross-sectional view taken along line AA in Fig. 1(a), Fig. 1(c) is a rear view, and Fig. 1(d) is a side view.

[0011] In FIG. 1, d1 indicates the width direction of the rim portion 10, O indicates the outside in the width direction, and I indicates the inside in the width direction. The outside in the width direction faces the outside of the vehicle when the wheel 1 is attached to the vehicle, and the inside in the width direction faces the inside of the vehicle when the wheel 1 is attached to the vehicle. Hereinafter, as necessary, the direction of d1 will be referred to as the width direction d1, O as the outside of the width direction d1, and I as the inside of the width direction d1. Note that in FIG. 1, the wheel 1 viewed from the outside in the width direction d1 is shown as a front view.

[0012] Referring to FIG. 1, the wheel 1 is a substantially cylindrical structure with an axis m as a central axis. The wheel 1 includes a rim portion 10, a disk portion 20, and a first strain gauge (strain gauge 100). C1 , 100 C2 , 100 C3 , and 100 C4 ) In the absence of a need to distinguish between them, the strain gauges may be collectively referred to as strain gauge 100.

[0013] The wheel 1 may have two or more first strain gauges, but this embodiment shows an example in which the wheel 1 has four first strain gauges. The wheel 1 further has bridge circuits 301-304 and a wireless transmission unit 340, which will be described later with reference to FIG.

[0014] As shown in FIG. 1, the rim portion 10 is a substantially cylindrical member with a width W. In the example of FIG. 1, the outer peripheral surface 10a of the rim portion 10 is flat in a side view. However, the outer peripheral surface 10a of the rim portion 10 may not be flat and may have a complex shape including projections and recesses. The disk portion 20 extends in the radial direction from the inner peripheral surface near the outside of the rim portion 10 in the width direction d1. The disk portion 20 is formed integrally with the rim portion 10, for example. The disk portion 20 may include a plurality of spoke portions. The rim portion 10 and the disk portion 20 may be manufactured integrally by a process including casting, for example, using an aluminum alloy, a magnesium alloy, or the like.

[0015] In FIG. 1, line S is an imaginary line passing through the center of the width direction d1 of the outer circumferential surface 10a of the rim portion 10. In the wheel 1, four first measurement regions R1 are defined at regular intervals in the circumferential direction at the center of the width direction d1 of the rim portion 10. Here, the center is defined as a range of ±W / 10 in the width direction d1 from the line S. The first measurement region R can be, for example, a square region whose center passes through the line S and whose sides are parallel or perpendicular to the line S. The length of one side of the square can be, for example, W / 5.

[0016] Each of the first measurement regions R1 is provided with one strain gauge (strain gauge 100 C1 , 100 C2 , 100 C3 , or 100 C4 ) are placed. Strain gauge 100 C1 ~100 C4 The strain gauge 100 can be fixed to the outer peripheral surface 10a of the rim portion 10 by, for example, an adhesive. C1 ~100 C4 may be fixed to the inner peripheral surface 10b of the rim portion 10.

[0017] In addition, the strain gauge is arranged in the first measurement region R1. C1 ~100 C4 This means that the grid portion of the strain gauge 100 is disposed within the first measurement region R1. C1 ~100 C4 The part other than the grid part may extend outside the first measurement region R1. C1 ~100 C4 The center of the grid portion may pass through the line S. The grid portion will be described later.

[0018] Strain Gauge 100 C1 ~100 C4 In other words, in FIG. 1(a), adjacent strain gauges 100 are arranged at equal intervals in the circumferential direction. C1 and strain gauge 100 C4 The central angle θ between the rim portion 10 and the adjacent strain gauge is 90 degrees. The central angle between the other adjacent strain gauges is also 90 degrees. Here, 90 degrees allows for an error of ±5 degrees (same below). The central angle between adjacent strain gauges is the angle between the two line segments connecting the axis m (center of the rim portion 10) and the center of the grid portion of the adjacent strain gauge in FIG. 1(a). The center of the grid portion will be described later.

[0019] Fig. 2 is a diagram illustrating a circuit block of the wheel according to the first embodiment. As shown in Fig. 2, the wheel 1 can be configured to include bridge circuits 301-304, a power supply unit 310, an analog front-end unit 320, a control unit 330, and a wireless transmission unit 340. The circuit block of the wheel 1 is mounted on, for example, a flexible substrate. The flexible substrate can be disposed in a vacant area of ​​the wheel 1. The flexible substrate can be attached, for example, to the inner circumferential surface of the rim portion 10.

[0020] The bridge circuit includes a strain gauge 100 disposed in each of the first measurement regions R1. C1 ~100 C4The bridge circuit 301 is provided for each of the strain gauges 100. C1 Based on the change in resistance of the strain gauge 100 C1 The bridge circuit 302 generates a first strain waveform in a first measurement region R1 in which the strain gauge 100 is arranged. C2 Based on the change in resistance of the strain gauge 100 C2 The bridge circuit 303 generates a first strain waveform in the first measurement region R1 in which the strain gauge 100 is arranged. C3 Based on the change in resistance of the strain gauge 100 C3 The bridge circuit 304 generates a first strain waveform in the first measurement region R1 where the strain gauge 100 is arranged. C4 Based on the change in resistance of the strain gauge 100 C4 A first strain waveform is generated in a first measurement region R1 in which the first measurement region R1 is located.

[0021] 3 is a diagram illustrating one example of a bridge circuit. In FIG. 3, one of the four sides of a bridge circuit 301 is connected to a strain gauge 100. C1 The other three sides are composed of fixed resistors R1 to R3. C1 A DC voltage is supplied from the power supply unit 310 between the connection between the fixed resistor R1 and the connection between the fixed resistor R2 and the fixed resistor R3. C1 The output of the bridge circuit 301 can be obtained between the connection part between the fixed resistor R1 and the fixed resistor R2 and the connection part between the fixed resistor R1 and the fixed resistor R2. C1 The first distortion waveform is based on a change in the resistance value of the resistor 310 and is input to the analog front-end section 320.

[0022] Although the bridge circuit 301 has been described with reference to FIG. 3, the bridge circuits 302 to 304 are C1 Instead of strain gauge 100 C2 ~100 C4The bridge circuits 302 to 304 can be configured in the same manner as the bridge circuit 301, except that each bridge circuit 302 to 304 forms one side. C2 ~Strain gauge 100 C4 The first distortion waveform is based on a change in the resistance value of the resistor 310 and is input to the analog front-end section 320.

[0023] 2, the power supply unit 310 is, for example, a button battery, a rechargeable lithium battery, etc. The power supply unit 310 can supply power to the bridge circuits 301 to 304, the analog front-end unit 320, the control unit 330, and the wireless transmission unit 340.

[0024] The analog front-end unit 320 includes, for example, an amplifier circuit, an A / D conversion circuit (analog / digital conversion circuit), etc. The analog front-end unit 320 may include a temperature compensation circuit. The analog front-end unit 320 may be implemented as an IC, or may be configured using individual components.

[0025] The analog front-end unit 320 receives the first distorted waveform from each of the bridge circuits 301 to 304, and amplifiers and the like may be provided individually for the four bridge circuits, or may be provided in common for some or all of them.

[0026] In the analog front-end unit 320, the first distortion waveforms input from each of the bridge circuits 301 to 304 are amplified by an amplifier circuit, converted into a digital signal by an A / D conversion circuit, and output as information based on the first distortion waveform (hereinafter referred to as first distortion information) to the control unit 330. If the analog front-end unit 320 includes a temperature compensation circuit, a temperature compensated digital signal is sent to the control unit 330.

[0027] The control unit 330 can perform arithmetic processing on the digitized first distortion information sent from the analog front-end unit 320. Examples of the arithmetic processing include noise removal, smoothing, normalization, etc. The control unit 330 sends the first distortion information that has been subjected to the arithmetic processing to the wireless transmission unit 340.

[0028] Fig. 4 is an example of a hardware block diagram of the control unit. As shown in Fig. 4, the control unit 330 has, as main components, a CPU (Central Processing Unit) 331, a ROM (Read Only Memory) 332, a RAM (Random Access Memory) 333, an I / F (Interface) 334, and a bus line 335. The CPU 331, the ROM 332, the RAM 333, and the I / F 334 are connected to each other via the bus line 335. The control unit 330 may have other hardware blocks as necessary.

[0029] The CPU 331 controls each function of the control unit 330. The ROM 332, which is a storage means, stores various information and programs executed by the CPU 331 to control each function of the control unit 330. The RAM 333, which is a storage means, is used as a work area or the like for the CPU 331. The RAM 333 can also temporarily store predetermined information. The I / F 334 is an interface for connecting to other devices and the like, and is connected to, for example, the analog front-end unit 320, an external network, and the like.

[0030] The control unit 330 may be a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, or an ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), SOC (System On a Chip), or GPU (Graphics Processing Unit) designed to execute a predetermined function. The control unit 330 may also be a circuit module, etc.

[0031] Returning to the explanation of Fig. 2, the wireless transmission unit 340 transmits the first strain information received from the control unit 330 to the outside of the rim unit 10. For example, assume that a tire is mounted on the rim unit 10 of the wheel 1 and is mounted on a vehicle. In this case, as shown in Fig. 2, the wireless transmission unit 340 can transmit the first strain information received from the control unit 330 to the determination unit 501 of the receiving device 5.

[0032] The receiving device 5 is, for example, a computer mounted on the vehicle or a mobile device carried by the driver of the vehicle. The determining unit 501 can receive the first strain information transmitted by the wireless transmitting unit 340 and determine the state of the rim unit 10 and / or the tire based on the received information. The determining unit 501 can also transmit the determination result to the driver via, for example, a head-up display mounted on the vehicle or a display screen of the mobile device. The determining unit 501 may transmit the determination result to the driver by sound or flashing light.

[0033] The first strain information is obtained by detecting the reaction force transmitted from the road surface while the vehicle is traveling as a change in resistance value. In addition, the first strain information is obtained for each of the four first measurement areas R1 by a bridge circuit provided for each of the strain gauges arranged in the four first measurement areas R1.

[0034] The first strain information includes information about the wheel balance. Therefore, the determination unit 501 can continuously monitor the first strain information (resistance value) obtained for each of the four first measurement regions R1, and determine that the wheel balance is off by identifying the first measurement region R1 in which a resistance value different from the others is periodically detected. In addition, the determination unit 501 can immediately grasp when the balance weight peels off or falls off due to impact or aging.

[0035] Drivers can now constantly monitor wheel balance while driving, something that previously could only be checked when changing tires. If the wheels are out of balance, there is a risk that the vehicle will vibrate and cause the driver to lose control of the steering wheel. Furthermore, if the vehicle continues to be driven with poor wheel balance, the tires will wear unevenly, and there is a risk of a serious accident due to a puncture or burst. By constantly monitoring wheel balance while driving, it is possible to prevent such problems from occurring.

[0036] The first strain information includes information on the air pressure of the tire mounted on the rim portion 10, in addition to information on the hole bounce. Therefore, the determination unit 501 can detect a drop in the air pressure of the tire by, for example, comparing the sum of the first strain information obtained for each of the four first measurement regions R1 with a preset threshold value. This makes it possible to prevent tire troubles such as punctures and bursts.

[0037] In this way, it is possible to realize a condition determination device 8 having the wheel 1, a tire mounted on the rim portion 10 of the wheel 1, and a receiving device 5 having a determination unit 501. In the condition determination device 8, the determination unit 501 receives the first strain information transmitted by the wireless transmission unit 340, and can determine the condition of the rim portion 10 and / or the tire based on the received information. Determining the condition of the rim portion 10 and / or the tire, as described above, involves checking the wheel balance with the wheel 1 mounted on a vehicle and checking for a drop in tire air pressure.

[0038] In addition, strain gauge 100 C1~100 C4 Although the position may be anywhere in the width direction d1, it is preferable to place the sensor in the center of the width direction d1 since it is possible to detect a wide range of strain.

[0039] [Strain gauge 100] Fig. 5 is a plan view illustrating the strain gauge according to the first embodiment. Fig. 6 is a cross-sectional view (part 1) illustrating the strain gauge according to the first embodiment, showing a cross section along line BB in Fig. 5.

[0040] 5 and 6, the strain gauge 100 has a substrate 110, a resistor 130, wiring 140, electrodes 150, and a cover layer 160. That is, the strain gauge 100 has the resistor 130 as a detection element. The cover layer 160 can be provided as necessary. For convenience, only the outer edge of the cover layer 160 is shown by a dashed line in FIGS. 5 and 6. First, each part constituting the strain gauge 100 will be described in detail.

[0041] In addition, in FIG. 5 and FIG. 6, for convenience, in the strain gauge 100, the side of the substrate 110 on which the resistor 130 is provided is referred to as the "upper side", and the side on which the resistor 130 is not provided is referred to as the "lower side". In addition, the surface located on the upper side of each part is referred to as the "upper surface", and the surface located on the lower side of each part is referred to as the "lower surface". However, the strain gauge 100 can also be used upside down. In addition, the strain gauge 100 can also be arranged at any angle. In addition, in FIG. 5 and FIG. 6, the plan view refers to viewing the object in a normal direction from the upper side to the lower side with respect to the upper surface 110a of the substrate 110. And, the planar shape refers to the shape of the object when the object is viewed in the normal direction. The strain gauge 100 is attached to the rim part 10 so that the lower surface 110b of the substrate 110 faces the rim part 10 side.

[0042] The substrate 110 is a member that serves as a base layer for forming the resistor 130 and the like. The substrate 110 is flexible. There is no particular limit to the thickness of the substrate 110, and it may be appropriately determined depending on the intended use of the strain gauge 100, etc. For example, the thickness of the substrate 110 may be about 5 μm to 500 μm. From the viewpoint of the transferability of strain from the rim portion to the sensing portion and the dimensional stability against environmental changes, the thickness of the substrate 110 is preferably within the range of 5 μm to 200 μm. From the viewpoint of insulation, the thickness of the substrate 110 is preferably 10 μm or more.

[0043] The substrate 110 is formed from an insulating resin film such as, for example, PI (polyimide) resin, epoxy resin, PEEK (polyether ether ketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, LCP (liquid crystal polymer) resin, polyolefin resin, etc. The film refers to a member having a thickness of about 500 μm or less and having flexibility.

[0044] When the base material 110 is formed from an insulating resin film, the insulating resin film may contain a filler, impurities, etc. For example, the base material 110 may be formed from an insulating resin film containing a filler such as silica or alumina.

[0045] Examples of materials other than resin for the base material 110 include crystalline materials such as SiO2, ZrO2 (including YSZ), Si, Si2N3, Al2O3 (including sapphire), ZnO, and perovskite ceramics (CaTiO3, BaTiO3). In addition to the above-mentioned crystalline materials, amorphous glass or the like may be used as the material for the base material 110. Metals such as aluminum, aluminum alloy (duralumin), and titanium may also be used as the material for the base material 110. When a metal base material 110 is used, an insulating film is provided so as to cover the upper surface 110a.

[0046] The resistor 130 is a thin film formed in a predetermined pattern on the upper side of the substrate 110. In the strain gauge 100, the resistor 130 is a sensing part that receives strain and generates a resistance change. The resistor 130 may be formed directly on the upper surface 110a of the substrate 110, or may be formed on the upper surface 110a of the substrate 110 via another layer. For convenience, the resistor 130 is shown in FIG. 5 as having a dense matte pattern.

[0047] Resistor 130 is a grid section in which multiple elongated portions are arranged at predetermined intervals with their longitudinal direction in the same direction (the direction of line BB in the example of FIG. 5), and the ends of adjacent elongated portions are alternately connected to form a zigzag folded structure as a whole. The longitudinal direction of the multiple elongated portions is the grid direction, and the direction perpendicular to the grid direction is the grid width direction (the direction perpendicular to line BB in the example of FIG. 5). In resistor 130, the intersection of the center in the grid direction and the center in the grid width direction is the center of the grid section.

[0048] One end in the longitudinal direction of the two elongated portions located at the outermost sides in the grid width direction is bent in the grid width direction to form terminal ends 130e1 and 130e2 of the resistor 130 in the grid width direction. The terminal ends 130e1 and 130e2 of the resistor 130 in the grid width direction are electrically connected to the electrode 150 via the wiring 140. In other words, the wiring 140 electrically connects the terminal ends 130e1 and 130e2 of the resistor 130 in the grid width direction to the electrodes 150.

[0049] To detect the reaction force transmitted from the road surface while the vehicle is traveling, it is preferable to arrange the strain gauge 100 so that the grid direction faces the radial direction of the rim portion 10. However, depending on the shape of the wheel, it may be difficult to arrange the strain gauge 100 in the radial direction of the rim portion 10. In that case, the strain gauge 100 may be arranged so that the grid direction faces the axis m direction or the circumferential direction of the rim portion 10.

[0050] The resistor 130 can be formed, for example, from a material containing Cr (chromium), a material containing Ni (nickel), or a material containing both Cr and Ni. That is, the resistor 130 can be formed from a material containing at least one of Cr and Ni. An example of a material containing Cr is a Cr mixed phase film. An example of a material containing Ni is Cu-Ni (copper nickel). An example of a material containing both Cr and Ni is Ni-Cr (nickel chromium).

[0051] Here, the Cr mixed phase film is a film in which Cr, CrN, Cr2N, etc. are mixed. The Cr mixed phase film may contain inevitable impurities such as chromium oxide.

[0052] The thickness of the resistor 130 is not particularly limited and may be appropriately determined depending on the intended use of the strain gauge 100. For example, the thickness of the resistor 130 may be about 0.05 μm to 2 μm. In particular, when the thickness of the resistor 130 is 0.1 μm or more, the crystallinity of the crystals constituting the resistor 130 (for example, the crystallinity of α-Cr) is improved. Furthermore, when the thickness of the resistor 130 is 1 μm or less, (i) cracks in the film and (ii) warping of the film from the substrate 110 caused by the internal stress of the film constituting the resistor 130 are reduced.

[0053] Considering the need to prevent lateral sensitivity and to prevent disconnection, the width of resistor 130 is preferably 10 μm to 100 μm. More specifically, the width of resistor 130 is preferably 10 μm to 70 μm, and more preferably 10 μm to 50 μm.

[0054] For example, when the resistor 130 is a Cr mixed-phase film, the stability of the gauge characteristics can be improved by making α-Cr (alpha chromium) which is a stable crystal phase the main component. For example, when the resistor 130 is a Cr mixed-phase film, the resistor 130 can make α-Cr the main component, so that the gauge factor of the strain gauge 100 is 10 or more, and the gauge factor temperature coefficient TCS and the resistance temperature coefficient TCR can be in the range of -1000 ppm / °C to +1000 ppm / °C. Here, the "main component" means a component that occupies 50% by weight or more of the total material constituting the resistor. From the viewpoint of improving the gauge characteristics, the resistor 130 preferably contains 80% by weight or more of α-Cr. Furthermore, from the same viewpoint, the resistor 130 more preferably contains 90% by weight or more of α-Cr. Note that α-Cr is Cr with a bcc structure (body-centered cubic lattice structure).

[0055] In addition, when the resistor 130 is a Cr mixed-phase film, the Cr mixed-phase film preferably contains 20% by weight or less of CrN and Cr2N. By containing 20% ​​by weight or less of CrN and Cr2N in the Cr mixed-phase film, a decrease in the gauge factor of the strain gauge 100 can be suppressed.

[0056] In addition, the ratio of CrN and Cr2N in the Cr mixed phase film is preferably such that the ratio of Cr2N is 80% by weight or more and less than 90% by weight with respect to the total weight of CrN and Cr2N. More specifically, the ratio is more preferably such that the ratio of Cr2N is 90% by weight or more and less than 95% by weight with respect to the total weight of CrN and Cr2N. Cr2N has semiconductor properties. Therefore, by setting the ratio of Cr2N to 90% by weight or more and less than 95% by weight, the decrease in TCR (negative TCR) becomes more significant. Furthermore, by setting the ratio of Cr2N to 90% by weight or more and less than 95% by weight, the resistor 130 is less likely to become ceramic, and the resistor 130 is less likely to be brittle fractured.

[0057] On the other hand, CrN has the advantage of being chemically stable. By including more CrN in the Cr mixed-phase film, the possibility of unstable N being generated can be reduced, resulting in a stable strain gauge. Here, "unstable N" refers to trace amounts of N2 or atomic N that may be present in the Cr mixed-phase film. This unstable N may escape to the outside of the film depending on the external environment (e.g., high-temperature environment). When unstable N escapes to the outside of the film, the film stress of the Cr mixed-phase film may change.

[0058] In the strain gauge 100, when a Cr mixed-phase film is used as the material of the resistor 130, it is possible to realize high sensitivity and miniaturization. For example, while the output of a conventional strain gauge was about 0.04 mV / 2 V, when a Cr mixed-phase film is used as the material of the resistor 130, an output of 0.3 mV / 2 V or more can be obtained. In addition, while the size (gauge length x gauge width) of a conventional strain gauge was about 3 mm x 3 mm, when a Cr mixed-phase film is used as the material of the resistor 130, the size (gauge length x gauge width) can be miniaturized to about 0.3 mm x 0.3 mm.

[0059] The wiring 140 is provided on the substrate 110. The wiring 140 is electrically connected to the resistor 130 and the electrode 150. The wiring 140 is not limited to being linear, and may be in any pattern. The wiring 140 may have any width and any length. For convenience, the wiring 140 is shown in FIG. 5 as having a matte pattern with a lower density than the resistor 130.

[0060] The electrode 150 is provided on the substrate 110. The electrode 150 is electrically connected to the resistor 130 via the wiring 140. The electrode 150 is formed in a substantially rectangular shape wider than the wiring 140 in a plan view. The electrodes 150 are a pair of electrodes for outputting a change in the resistance value of the resistor 130 caused by distortion to the outside. A metal layer having low resistance such as copper or a metal layer having good solderability such as gold may be laminated on the upper surface of the electrode 150. Although the resistor 130, the wiring 140, and the electrode 150 are denoted by different reference numerals for convenience, they can be integrally formed from the same material in the same process. In FIG. 5, the electrode 150 is shown with a matte pattern having the same density as the wiring 140 for convenience.

[0061] The cover layer 160 (protective layer) is provided on the upper surface 110a of the base material 110 as necessary so as to cover the resistor 130 and the wiring 140 and expose the electrodes 150. Examples of materials for the cover layer 160 include insulating resins such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, and composite resins (e.g., silicone resin, polyolefin resin). The cover layer 160 may contain a filler or a pigment. The thickness of the cover layer 160 is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness of the cover layer 160 can be about 2 μm to 30 μm. By providing the cover layer 160, it is possible to suppress mechanical damage and the like from occurring in the resistor 130. In addition, by providing the cover layer 160, it is possible to protect the resistor 130 from moisture and the like.

[0062] [Manufacturing method of strain gauge 100] In the strain gauge 100 according to this embodiment, a resistor 130, wiring 140, electrodes 150, and a cover layer 160 are formed on a substrate 110. Note that another layer (such as a functional layer described below) may be formed between the substrate 110 and the layers of these members.

[0063] A method for manufacturing the strain gauge 100 will be described below. To manufacture the strain gauge 100, first, a base material 110 is prepared, and a metal layer (for convenience, referred to as metal layer A) is formed on an upper surface 110a of the base material 110. The metal layer A is a layer that is finally patterned to become the resistor 130, the wiring 140, and the electrodes 150. Therefore, the material and thickness of the metal layer A are the same as the material and thickness of the resistor 130, the wiring 140, and the electrodes 150 described above.

[0064] The metal layer A can be formed by, for example, magnetron sputtering using a target made of a raw material capable of forming the metal layer A. Instead of magnetron sputtering, the metal layer A may be formed by reactive sputtering, vapor deposition, arc ion plating, pulsed laser deposition, or the like. After the metal layer A is formed on the upper surface 110a of the base material 110, the metal layer A is patterned by a well-known photolithography method into a planar shape similar to that of the resistor 130, the wiring 140, and the electrode 150 in FIG. 5.

[0065] Alternatively, a base layer may be formed on the upper surface 110a of the base material 110, and then the metal layer A may be formed. For example, a functional layer of a predetermined thickness may be vacuum-formed by conventional sputtering on the upper surface 110a of the base material 110. By providing a base layer in this manner, the gauge characteristics of the strain gauge 100 can be stabilized.

[0066] In the present application, the functional layer refers to a layer having a function of promoting the crystal growth of at least the upper layer, metal layer A (resistor 130). The functional layer preferably further has a function of preventing oxidation of metal layer A due to oxygen or moisture contained in base material 110, and / or a function of improving adhesion between base material 110 and metal layer A. The functional layer may further have other functions.

[0067] The insulating resin film constituting the base material 110 may contain oxygen or moisture, and Cr may form a self-oxidized film. Therefore, particularly when the metal layer A contains Cr, it is preferable to form a functional layer having a function of preventing the oxidation of the metal layer A.

[0068] In this way, by providing a functional layer below the metal layer A, it is possible to promote crystal growth of the metal layer A, and to fabricate a metal layer A consisting of a stable crystal phase. As a result, the stability of the gauge characteristics of the strain gauge 100 is improved. In addition, the material constituting the functional layer diffuses into the metal layer A, thereby improving the gauge characteristics of the strain gauge 100.

[0069] Examples of materials for the functional layer include one or more metals selected from the group consisting of Cr (chromium), Ti (titanium), V (vanadium), Nb (niobium), Ta (tantalum), Ni (nickel), Y (yttrium), Zr (zirconium), Hf (hafnium), Si (silicon), C (carbon), Zn (zinc), Cu (copper), Bi (bismuth), Fe (iron), Mo (molybdenum), W (tungsten), Ru (ruthenium), Rh (rhodium), Re (rhenium), Os (osmium), Ir (iridium), Pt (platinum), Pd (palladium), Ag (silver), Au (gold), Co (cobalt), Mn (manganese), and Al (aluminum), an alloy of any of the metals in this group, or a compound of any of the metals in this group.

[0070] 7 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. FIG 7 shows the cross-sectional shape of the strain gauge 100 when a functional layer 120 is provided as an underlying layer for the resistor 130, the wiring 140, and the electrodes 150.

[0071] The planar shape of the functional layer 120 may be patterned to be substantially the same as the planar shapes of the resistor 130, the wiring 140, and the electrodes 150, for example. However, the planar shapes of the functional layer 120, the resistor 130, the wiring 140, and the electrodes 150 do not have to be substantially the same. For example, when the functional layer 120 is formed from an insulating material, the functional layer 120 may be patterned to a shape different from the planar shapes of the resistor 130, the wiring 140, and the electrodes 150. In this case, the functional layer 120 may be patterned to be solid in the area where the resistor 130, the wiring 140, and the electrodes 150 are formed, for example. Alternatively, the functional layer 120 may be formed in a solid manner over the entire upper surface of the base material 110.

[0072] After forming the resistor 130, the wiring 140, and the electrodes 150, a cover layer 160 is formed on the upper surface 110a of the base material 110 as necessary. The cover layer 160 covers the resistor 130 and the wiring 140, but the electrodes 150 may be exposed from the cover layer 160. For example, the cover layer 160 can be formed by laminating a semi-cured thermosetting insulating resin film on the upper surface 110a of the base material 110 so as to cover the resistor 130 and the wiring 140 and expose the electrodes 150, and then heating and curing the insulating resin film. Through the above steps, the strain gauge 100 is completed.

[0073] Modification of the First Embodiment In the modified example of the first embodiment, an example in which another measurement area is defined apart from the first measurement area in the width direction of the rim part, and an example in which a plurality of resistors (grid part) are arranged in one measurement area are shown. Note that in the modified example of the first embodiment, the description of the same components as those in the embodiment already described may be omitted.

[0074] Figure 8 is a diagram illustrating a wheel according to Modification 1 of the first embodiment. In detail, Figure 8(a) is a front view, Figure 8(b) is a cross-sectional view taken along line AA in Figure 8(a), Figure 8(c) is a rear view, and Figure 8(d) is a side view.

[0075] The wheel 1A shown in FIG. 8 includes a plurality of second measurement areas R2 that are separated from the first measurement area R1 in the width direction d1 of the rim portion 10 and are defined at regular intervals in the circumferential direction, and a second strain gauge (strain gauge 100 F1 , 100 F2 , 100 F3 , and 100 F4 ) is different from wheel 1. Although wheel 1A may have two or more second strain gauges, this embodiment shows an example in which wheel 1A has four second strain gauges.

[0076] Each second measurement region R2 can be defined at one end or the other end of the width direction d1 of the rim portion 10. In the example of FIG. 8, each second measurement region R2 is defined on the outer end face of the rim portion 10 in the width direction d1. The second measurement region R2 can be defined, for example, in a range of W / 5 in the width direction d1 from the outer end face of the rim portion 10 in the width direction d1. Each second measurement region R2 may be defined on the outer peripheral surface 10a or inner peripheral surface 10b of the rim portion 10 in a range of W / 5 from the outer end face of the rim portion 10 in the width direction d1.

[0077] In each of the second measurement areas R2, one strain gauge (strain gauge 100 F1 , 100 F2 , 100 F3 , or 100 F4 ) are placed. Strain gauge 100 F1 ~100 F4 can be fixed, for example, to the outer end face of the rim portion 10 in the width direction d1 by an adhesive.

[0078] In this way, the wheel 1A has two rows of strain gauges in a side view. C1 ~100 C4 is the strain gauge in the first row, strain gauge 100 F1 ~100 F4 is the second row of strain gauges.

[0079] Strain Gauge 100 C1 ~100 C4 and strain gauge 100 F1 ~100 F4 are arranged at different positions in the width direction d1. F1 strain gauge 100 C1 In other words, in FIG. 8(a), the strain gauge 100 is disposed at approximately the same position in the radial direction as the strain gauge 100. F1 strain gauge 100 C1 In FIG. 8(b), the axis m and the strain gauge 100 F1 The distance between the axis m and the strain gauge 100C1 Approximately equal to the distance between the strain gauge and the F2 and strain gauge 100 C2 Positional relationship with strain gauge 100 F3 and strain gauge 100 C3 The positional relationship with the strain gauge 100 F4 and strain gauge 100 C4 The same applies to the positional relationship with the strain gauge 100. F1 ~100 F4 strain gauge 100 C1 ~100 C4 Similarly, they are spaced equally apart.

[0080] The bridge circuit includes strain gauges 100 disposed in the second measurement regions R2 in the same manner as in the first embodiment. F1 ~100 F4 The bridge circuit 301 is provided for each of the strain gauges 100. F1 Based on the change in resistance of the strain gauge 100 F1 The bridge circuit 302 generates a second strain waveform in the second measurement region R2 in which the strain gauge 100 is disposed. F2 Based on the change in resistance of the strain gauge 100 F2 The bridge circuit 303 generates a second strain waveform in the second measurement region R2 in which the strain gauge 100 is arranged. F3 Based on the change in resistance of the strain gauge 100 F3 The bridge circuit 304 generates a second strain waveform in the second measurement region R2 where the strain gauge 100 is arranged. F4 Based on the change in resistance of the strain gauge 100 F4 A second strain waveform is generated in the second measurement region R2 in which the second measurement region R2 is located.

[0081] Strain Gauge 100 F1 ~100 F4 strain gauge 100 C1 ~100 C42 to 4 are also formed in addition to the bridge circuit. Therefore, in wheel 1A, wireless transmitting unit 340 can transmit the first distortion information and information based on the second distortion waveform (hereinafter referred to as second distortion information) received from control unit 330 to determination unit 501 of receiving device 5.

[0082] The determination unit 501 can determine the wheel imbalance and the drop in tire air pressure in the same manner as the wheel 1. Furthermore, the wheel 1A includes a strain gauge 100. F1 ~100 F4 and strain gauge 100 C1 ~100 C4 and are arranged at different positions in the width direction d1, the first strain information and the second strain information include information regarding uneven wear of the tire mounted on the rim portion 10.

[0083] For example, if the tire near the outer side in the width direction d1 is unevenly worn and the tire near the center in the width direction d1 is not unevenly worn, the strain gauge 100 C1 ~100 C4 The sum of the resistance values ​​of the strain gauges is F1 ~100 F4 and strain gauge 100 C1 ~100 C4 The sum of the resistance values ​​of the two resistors will be different.

[0084] Therefore, the determination unit 501 can determine the presence or absence of uneven wear of the tire by comparing the sum of the first strain information obtained for each of the four first measurement regions R1 with the sum of the second strain information obtained for each of the four second measurement regions R2. This makes it possible to clarify the frequency of tire rotation, thereby realizing a longer tire life.

[0085] 9A and 9B are diagrams illustrating a wheel according to Modification 2 of the first embodiment. In detail, Fig. 9A is a front view, Fig. 9B is a cross-sectional view taken along line AA in Fig. 9A, Fig. 9C is a rear view, and Fig. 9D is a side view.

[0086] The wheel 1B shown in FIG. 9 includes a plurality of third measurement areas R3 that are separated from the first measurement area R1 and the second measurement area R2 in the width direction d1 of the rim portion 10 and are defined at regular intervals in the circumferential direction, and a third strain gauge (strain gauge 100 R1 , 100 R2 , 100 R3 , and 100 R4 ) The wheel 1B differs from the wheel 1A in that the wheel 1B further includes two or more third strain gauges. Although the wheel 1B may include two or more third strain gauges, the present embodiment shows an example in which the wheel 1B includes four third strain gauges.

[0087] Each third measurement region R3 can be defined at one end or the other end of the width direction d1 of the rim portion 10. In the example of FIG. 9, each third measurement region R3 is defined on the inner end face of the rim portion 10 in the width direction d1. The third measurement region R3 can be defined, for example, in a range of W / 5 in the width direction d1 from the inner end face of the rim portion 10 in the width direction d1. Each third measurement region R3 may be defined on the outer peripheral surface 10a or inner peripheral surface 10b of the rim portion 10 in a range of W / 5 from the inner end face of the rim portion 10 in the width direction d1.

[0088] In each of the third measurement areas R3, one strain gauge (strain gauge 100 R1 , 100 R2 , 100 R3 , or 100 R4 ) are placed. Strain gauge 100 R1 ~100 R4 can be fixed, for example, to the inner end face of the rim portion 10 in the width direction d1 by an adhesive.

[0089] In this way, the wheel 1B has three rows of strain gauges in a side view. C1 ~100 C4 is the strain gauge in the first row, strain gauge 100 F1 ~100 F4 is the strain gauge in the second row, strain gauge 100 R1 ~100 R4 is the third row of strain gauges.

[0090] Strain Gauge 100 C1 ~100 C4 and strain gauge 100 F1 ~100 F4 and strain gauge 100 R1 ~100 R4 are arranged at different positions in the width direction d1. R1 strain gauge 100 C1 and 100 F1 In other words, in FIG. 9(a), the strain gauge 100 is disposed at approximately the same position in the radial direction as the strain gauge 100. R1 strain gauge 100 C1 and 100 F1 In FIG. 9(b), the axis m and the strain gauge 100 R1 The distance between the axis m and the strain gauge 100 C1 The distance between the axis m and the strain gauge 100 F1 Approximately equal to the distance between the strain gauge and the R2 and strain gauge 100 F2 and strain gauge 100 C2 Positional relationship with strain gauge 100 R3 and strain gauge 100 F3 and strain gauge 100 C3 The positional relationship with the strain gauge 100 R4 and strain gauge 100 F4 and strain gauge 100 C4 The same applies to the positional relationship with the strain gauge 100. R1 ~100 R4 strain gauge 100 C1 ~100 C4 and strain gauge 100 F1 ~100 F4 Similarly, they are spaced equally apart.

[0091] The bridge circuit includes strain gauges 100 disposed in the third measurement regions R3 in the same manner as in the first embodiment. R1 ~100 R4 The bridge circuit 301 is provided for each of the strain gauges 100.R1 Based on the change in resistance of the strain gauge 100 R1 The bridge circuit 302 generates a third strain waveform in the third measurement region R3 in which the strain gauge 100 is disposed. R2 Based on the change in resistance of the strain gauge 100 R2 The bridge circuit 303 generates a third strain waveform in the third measurement region R3 in which the strain gauge 100 is disposed. R3 Based on the change in resistance of the strain gauge 100 R3 The bridge circuit 304 generates a third strain waveform in the third measurement region R3 where the strain gauge 100 is arranged. R4 Based on the change in resistance of the strain gauge 100 R4 A third strain waveform is generated in the third measurement region R3 in which the third measurement region R3 is located.

[0092] Strain Gauge 100 R1 ~100 R4 strain gauge 100 C1 ~100 C4 and strain gauge 100 F1 ~100 F4 Similarly, the circuit connections described with reference to Figures 2 to 4 are also made other than the bridge circuit. Therefore, in wheel 1B, wireless transmitting unit 340 can transmit the first distortion information, the second distortion information, and information based on the third distortion waveform (hereinafter referred to as third distortion information) received from control unit 330 to determination unit 501 of receiving device 5.

[0093] The determination unit 501 can determine the wheel imbalance and the drop in tire air pressure in the same manner as the wheels 1 and 1A. R1 ~100 R4 and strain gauge 100 C1 ~100 C4 and strain gauge 100 F1 ~100 F4and are arranged at different positions in the width direction d1, the first strain information, the second strain information, and the third strain information contain more information about uneven wear of the tire mounted on the rim portion 10. In other words, they contain information about uneven wear near the outer side in the width direction d1, near the center in the width direction d1, and / or near the inner side in the width direction d1.

[0094] Therefore, the determination unit 501 can determine the presence or absence of uneven wear in the tire and the location of the uneven wear more accurately than the wheel 1A by comparing the sum of the first strain information obtained for each of the four first measurement regions R1, the sum of the second strain information obtained for each of the four second measurement regions R2, and the sum of the third strain information obtained for each of the four third measurement regions R3. This makes it possible to more clearly determine the frequency of tire rotation, thereby achieving a further long life for the tire.

[0095] Figure 10 is a diagram illustrating a wheel according to Modification 3 of the first embodiment. In detail, Figure 10(a) is a front view, Figure 10(b) is a cross-sectional view taken along line AA in Figure 10(a), Figure 10(c) is a rear view, and Figure 10(d) is a side view.

[0096] The wheel 1C shown in FIG. 10 is provided with a protrusion 10x that protrudes radially from the inner peripheral surface 10b of the rim portion 10, and a strain gauge 100 is attached to the inner surface of the protrusion 10x in the width direction d1. C1 ~100 C4 The difference from the wheel 1B is that the strain gauge 100 is arranged. C1 ~100 C4 The strain gauges are arranged at equal intervals. C1 ~100 C4 may be disposed on the outer surface of the protrusion 10x in the width direction d1. From the viewpoint of improving the detection accuracy, it is preferable that the protrusion 10x be thin.

[0097] Wheel 1C has three rows of strain gauges in side view, just like wheel 1B, and thus achieves the same effects as wheel 1B. Furthermore, wheel 1C does not have strain gauges on the outer peripheral surface of rim portion 10, so there is no reduction in the degree of freedom in designing the tire shape. That is, outer peripheral surface 10a of rim portion 10 is the side that comes into contact with the tire, and therefore, if strain gauges were placed on the outer peripheral surface of rim portion 10, there is a risk of reducing the degree of freedom in designing the tire shape, but wheel 1C does not have such a problem.

[0098] In addition, strain gauge 100 C1 ~100 C4 By disposing the strain gauges on the protrusions 10x, all the strain gauges can be disposed so that the grid direction faces the radial direction, thereby improving the detection accuracy of the reaction force transmitted from the road surface while the vehicle is traveling.

[0099] Depending on the tire shape, a convex portion may be provided that protrudes radially from the outer circumferential surface of the rim portion 10, and a strain gauge may be disposed on this convex portion.

[0100] 11 is a partially enlarged side view illustrating a wheel according to a fourth modified example of the first embodiment. The wheel 1D shown in FIG. 11 has a strain gauge 100 disposed in one first region R1. C2 The wheel 1C differs in that each strain gauge arranged in one measurement region has two resistors 130. In the other first region, second region, and third region, too, a strain gauge arranged in one measurement region has two resistors 130. The two resistors 130 can be arranged, for example, with the grid directions shifted by 90 degrees.

[0101] In the example of Figure 11, strain gauge 100 C2 The two resistors 130 are disposed on one substrate 110. However, the two resistors 130 may be disposed on separate substrates 110. In this application, the strain gauge 100 C2 This is included when the resistor 130 has two resistors 130.

[0102] The two resistors 130 are connected to form two sides of a bridge circuit 301 shown in Fig. 3. In this way, by arranging a strain gauge having two resistors 130 in each measurement area and connecting the two resistors to form a half-bridge circuit, the amplitude of the strain waveform obtained from one measurement area becomes larger than that of the wheel 1C. Therefore, it is possible to perform strain measurement with higher accuracy than the wheel 1C. Note that when multiple resistors 130 are arranged such that the central angle they form is 10 degrees or less, it is determined that the multiple resistors 130 are arranged in the same measurement area.

[0103] FIG. 12 is a partially enlarged side view illustrating a wheel according to a fifth modified example of the first embodiment. The wheel 1E shown in FIG. C2 The wheel 1D differs in that each strain gauge arranged in one measurement region has four resistors 130. In the other first region, second region, and third region, too, a strain gauge arranged in one measurement region has four resistors 130. Two resistors 130 adjacent to each other vertically can be arranged with the grid directions shifted by 90 degrees, for example. Also, two resistors 130 adjacent to each other horizontally can be arranged with the grid directions shifted by 90 degrees, for example.

[0104] In the example of Figure 12, strain gauge 100 C2 The four resistors 130 are arranged on one substrate 110. However, the four resistors 130 may be arranged on separate substrates 110. Alternatively, two substrates 110 on which two resistors 130 are arranged may be arranged side by side. In the present application, in these cases, the strain gauge 100 C2 This is included when the circuit has four resistors 130.

[0105] The four resistors 130 are connected to form each side of a bridge circuit 301 shown in Fig. 3. In this way, by arranging a strain gauge having four resistors 130 in one measurement area and connecting the four resistors to form a full bridge circuit, the amplitude of the strain waveform obtained from one measurement area becomes larger than that in the case of the wheel 1D. Therefore, it is possible to measure strain with higher accuracy than the wheel 1D.

[0106] The above describes preferred embodiments and the like. However, the wheels according to the present disclosure are not limited to the above-described embodiments and modifications. For example, various modifications and substitutions can be made to the wheels according to the above-described embodiments and the like without departing from the scope of the claims. [Explanation of symbols]

[0107] 1, 1A, 1B, 1C, 1D, 1E Wheel, 5 Receiving device, 8 State determination device, 10 Rim portion, 10a Outer peripheral surface, 10b Inner peripheral surface, 10x Convex portion, 20 Disk portion, 100 C1 ,100 C2 ,100 C3 ,100 C4 ,100 F1 ,100 F2 ,100 F3 ,100 F4 ,100 R1 ,100 R2 ,100 R3 ,100 R4 Strain gauge, 110 substrate, 110a upper surface, 120 functional layer, 130 resistor, 130e1, 130e2 termination, 140 wiring, 150 electrode, 160 cover layer, 301 to 304 bridge circuit, 310 power supply unit, 320 analog front end unit, 330 control unit, 331 CPU, 332 ROM, 333 RAM, 334 I / F, 335 bus line, 340 wireless transmission unit, 501 judgment unit

Claims

1. A rim portion and A plurality of first measurement areas defined at regular intervals in the rim portion in a circumferential direction; a first strain gauge disposed in each of the first measurement areas; a first bridge circuit provided for each of the first strain gauges arranged in the first measurement areas, the first bridge circuit generating a first strain waveform in each of the first measurement areas based on a change in resistance value of the first strain gauge; A wheel having a wireless transmitting unit that transmits information based on the first strain waveform to an outside of the rim portion.

2. The wheel of claim 1 , wherein each of the first measurement areas is defined at a central portion of the width of the rim portion.

3. The wheel according to claim 1 or 2, wherein the first strain gauge is disposed on a protrusion that protrudes radially from an outer circumferential surface or an inner circumferential surface of the rim portion.

4. a plurality of second measurement areas spaced apart from the first measurement areas in the width direction of the rim portion and defined at regular intervals in the circumferential direction; a second strain gauge disposed in each of the second measurement areas; a second bridge circuit provided for each of the second strain gauges arranged in the second measurement area, the second bridge circuit generating a second strain waveform in each of the second measurement areas based on a change in resistance value of the second strain gauge; The wheel according to claim 1 , wherein the wireless transmitting unit transmits information based on the first strain waveform and information based on the second strain waveform to an outside of the rim portion.

5. The wheel according to claim 4 , wherein each of the second measurement areas is defined at one end or the other end in a width direction of the rim portion.

6. The wheel according to claim 4 or 5, wherein the information based on the first strain waveform and the information based on the second strain waveform include information regarding uneven wear of a tire mounted on the rim portion.

7. a plurality of third measurement areas spaced apart from the first measurement area and the second measurement area in the width direction of the rim portion and defined at regular intervals in the circumferential direction; a third strain gauge disposed in each of the third measurement areas; a third bridge circuit provided for each of the third strain gauges arranged in the third measurement area, the third bridge circuit generating a third strain waveform in each of the third measurement areas based on a change in resistance value of the third strain gauge; The wheel according to claim 4 , wherein the wireless transmitting unit transmits the information based on the first strain waveform, the information based on the second strain waveform, and the information based on the third strain waveform to an outside of the rim portion.

8. Each of the second measurement areas is defined at one end of the rim portion in a width direction, 8. The wheel of claim 7, wherein each of the third measurement areas is defined at an opposite widthwise end of the rim portion.

9. 9. The wheel according to claim 7 or 8, wherein the information based on the first strain waveform, the information based on the second strain waveform, and the information based on the third strain waveform include information regarding uneven wear of a tire mounted on the rim portion.

10. 10. A wheel as claimed in claim 1, wherein information based on the first strain waveform includes information relating to hole bounce.

11. The wheel according to claim 1 , wherein the information based on the first strain waveform includes information related to an air pressure of a tire mounted on the rim portion.

12. The first strain gauge disposed in each of the first measurement regions has two resistors; 12. A wheel according to any one of the preceding claims, wherein the two resistors are connected to form a half-bridge circuit.

13. The first strain gauge disposed in each of the first measurement regions has four resistors; 12. A wheel as claimed in any one of the preceding claims, wherein the four resistors are connected to form a full bridge circuit.

14. A wheel according to any one of claims 1 to 13; A tire mounted on the rim portion; A receiving device having a determination unit, The determination unit receives the information transmitted by the wireless transmission unit, and determines a condition of the rim portion and / or the tire based on the information.

Images