Anomaly detection system and anomaly detection method

Abstract

Determine the location where the wheel malfunction occurred. [Solution] The abnormality determination system 1 of the embodiment includes a wheel 3 having a plurality of mounting holes formed at equal intervals in the circumferential direction, a plurality of sensors 10 attached to parts of the wheel 3 corresponding to at least two of the plurality of mounting holes and arranged at intervals in the circumferential direction, and a determination unit that compares the data detected by each of the plurality of sensors 10 and determines that the position corresponding to the sensor 10 that detected the data that changed the most with respect to a predetermined standard is the position where an abnormality occurred in the wheel 3.

Description

Technical Field

[0001] The present invention relates to an abnormality determination system and an abnormality determination method.

Background Art

[0002] Patent Document 1 discloses a method for detecting the deformed state of a sensor disposed inside a tire during vehicle travel. Patent Document 2 discloses an apparatus for detecting an abnormality in a wheel system of a vehicle based on a signal output from an acceleration sensor attached to a wheel of the vehicle. Patent Document 3 discloses an apparatus that detects an acceleration generated in the axle direction of a wheel by a detection means attached to the wheel, and determines that the wheel is not properly mounted when the detected acceleration is not within a predetermined range.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, there is a technique for detecting an abnormality such as loosening of a nut that is a fastening part of a wheel by a sensor attached to the wheel. However, with such a technique, it is impossible to determine which nut among a plurality of fastening parts has loosened (the position where the abnormality has occurred).

[0005] Therefore, an object of the present invention is to determine the position where an abnormality of a wheel has occurred.

Means for Solving the Problems

[0006] (1) An abnormality determination system according to one aspect of the present invention includes a wheel having a plurality of mounting holes formed at equal intervals in the circumferential direction, a plurality of sensors attached to the wheel at locations corresponding to at least two of the plurality of mounting holes and arranged at intervals in the circumferential direction, and a determination unit that compares the data detected by each of the plurality of sensors and determines that the position corresponding to the sensor that detected the data that changed the most with respect to a predetermined standard is the position where an abnormality occurred in the wheel. According to this embodiment, the location where a wheel abnormality occurred can be determined based on detection data from multiple sensors attached to the wheel.

[0007] (2) In the embodiment of (1) above, the sensor may be positioned on a virtual line that passes through the center of the mounting hole and extends radially when viewed from the axial direction of the wheel. According to this embodiment, the location where an abnormality (e.g., a loose nut) occurs in the mounting hole can be determined more effectively compared to the case where the sensor is positioned at a location offset from the virtual line when viewed from the axial direction.

[0008] (3) In the embodiment of (2) above, the wheel comprises a disc provided inside a cylindrical rim, the disc comprising a hub mounting portion having the plurality of mounting holes and being attached to a vehicle-side hub, and a connecting portion extending from the hub mounting portion toward the rim, wherein in a cross-sectional view including the rotation axis of the wheel, a part of the surface of the connecting portion has a first curved surface located at the outermost position in the axial direction and curving toward the radially outward, and a second curved surface located second from the outermost position in the axial direction and curving toward the radially inward or outward, and the sensor may be arranged on the second curved surface. According to this embodiment, the risk of interference with vehicle-side components can be reduced compared to the case where the sensor is arranged on the first curved surface.

[0009] (4) In the embodiment of (3) above, the sensor is a piezoelectric element, and the determination unit may compare the voltages generated by each of the plurality of piezoelectric elements and determine the position corresponding to the piezoelectric element that has detected the voltage that has changed the most relative to a predetermined standard as the position where the abnormality of the wheel occurred. According to this embodiment, the location where a malfunction in the wheel occurs can be determined based on the voltage generated by multiple piezoelectric elements attached to the wheel.

[0010] (5) In the embodiment of (4) above, the piezoelectric element may be formed in a flat plate shape. According to this embodiment, compared to the case where the piezoelectric element is formed in a curved shape (e.g., an arc shape), the rate of change of the voltage of the piezoelectric element when an abnormality occurs is larger, so the location where the wheel abnormality occurred can be determined more effectively.

[0011] (6) In any embodiment of (5) above, the piezoelectric element may be directly attached to the second curved surface via an adhesive. According to this embodiment, compared to the case in which a piezoelectric element formed in a flat plate shape is attached to the second curved surface via a gap-filling plate, the decrease in sensitivity of the piezoelectric element to wheel deformation can be reduced, making it possible to more effectively determine the location where an abnormality in the wheel has occurred.

[0012] (7) In any of the embodiments described in (4) to (6) above, the determination unit may be attached to the wheel and operated by the power generated by the piezoelectric element. According to this embodiment, the system can be implemented within the wheel.

[0013] (8) In any of the embodiments of (4) to (7) above, the wheel may further include a power storage unit that stores the power generated by the piezoelectric element. According to this embodiment, the electricity stored in the energy storage unit can be utilized.

[0014] (9) In the aspect of (8) above, a transmitting unit attached to the wheel, operated by the electric power stored in the power storage unit, and transmitting the abnormality may be further provided. According to this aspect, the abnormality can be transmitted using the electric power stored in the power storage unit.

[0015] (10) In any one of the aspects of (1) to (9) above, the determination unit may determine the abnormality while the vehicle equipped with the wheel is running. According to this aspect, the abnormality can be determined while the vehicle is running.

[0016] (11) In any one of the aspects of (1) to (10) above, the determination unit may determine loosening of the fastening portion of the wheel during running. According to this aspect, as an abnormality of the wheel, loosening of the fastening portion of the wheel during running can be determined.

[0017] (12) An abnormality determination method according to an aspect of the present invention includes a rotation step of rotating a wheel in which a plurality of mounting holes are formed at equal intervals in the circumferential direction, and at least two of the plurality of mounting holes in the wheel. Each of the plurality of sensors attached to the corresponding portions and arranged at intervals in the circumferential direction compares the detected data, and the position corresponding to the sensor that detected the data that has changed the most with respect to a predetermined reference is determined as the position where the abnormality of the wheel has occurred. And a determination step. According to this aspect, the position where the abnormality of the wheel has occurred can be determined based on the detected data of the plurality of sensors attached to the wheel.

Effect of the Invention

[0018] According to one aspect of the present invention, the position where the abnormality of the wheel has occurred can be determined based on the detected data of the plurality of sensors attached to the wheel.

Brief Description of the Drawings

[0019] [Figure 1]Flowchart showing an example of the abnormality determination system of the embodiment. [Figure 2] Schematic configuration diagram showing an example of a wheel mounted on a vehicle of the embodiment. [Figure 3] Front view showing an example of an attachable area of a plurality of sensors in the wheel of the embodiment. [Figure 4] Cross-sectional view showing an example of the attachment position of a sensor on the second curved surface of the wheel of the embodiment. [Figure 5] Front view showing an example of the attachment positions of a plurality of sensors in the wheel of the embodiment. [Figure 6] Front view showing another example of the attachment positions of a plurality of sensors in the wheel of the embodiment. [Figure 7] Flowchart showing an example of the abnormality determination method of the embodiment. [Figure 8] Diagram showing an example of the FEM analysis result which is the pre-verification of loosening detection of the embodiment. [Figure 9] Cross-sectional view of the wheel of the modified example of the embodiment, showing the attachment position of the piezoelectric element. [Figure 10] Cross-sectional view of the wheel of the example, showing the attachment position of the piezoelectric element. [Figure 11] Diagram showing the change in voltage when the nut of the piezoelectric elements installed on the first and second curved surfaces of the wheel of the example is loose. [Figure 12] Diagram showing the change in voltage when the nut of the flat plate element and the arc-shaped element installed on the second curved surface of the wheel of the example is loose. [Figure 13] Cross-sectional view showing an example of directly adhering a flat plate element to the second curved surface of the wheel of the example and an example using a gap-filling plate. [Figure 14] Diagram showing the change in voltage when the nut is loose in the example of directly adhering a flat plate element to the second curved surface of the wheel of the example and the example using a gap-filling plate.

Mode for Carrying Out the Invention

[0020] Embodiments of the present invention will be described below with reference to the drawings. In one embodiment, an abnormality detection system will be described as a system that detects looseness in the wheel fastening portion of a cargo vehicle such as a truck (an example of a vehicle) as an abnormality.

[0021] <Anomaly Detection System> Figure 1 is a flowchart showing an example of the abnormality detection system 1 of the embodiment. Figure 2 is a schematic configuration diagram showing an example of a wheel 3 mounted on a vehicle 2 of the embodiment. Referring to Figures 1 and 2, the abnormality detection system 1 includes a wheel 3 of the vehicle 2. For example, the wheel 3 is fixed to a vehicle-side hub (not shown) by bolts and nuts, which are fastening components. The wheel 3 rotates integrally with the vehicle-side hub in accordance with the rotation of the vehicle-side hub.

[0022] The abnormality detection system 1 further includes a sensor 10, a detection unit 11, a power storage unit 12, and a transmission unit 13. Each of the sensor 10, detection unit 11, power storage unit 12, and transmission unit 13 is attached to the wheel 3.

[0023] <wheel> Figure 3 is a front view showing an example of a mountable area for multiple sensors 10 in the wheel 3 of the embodiment. Referring to Figure 3, the wheel 3 has multiple mounting holes 32h formed at equal intervals in the circumferential direction. The wheel 3 includes a disc 31 provided inside a cylindrical rim 30. The disc 31 includes a hub mounting portion 32 formed with multiple mounting holes 32h and attached to the vehicle-side hub, and a connecting portion 33 extending from the hub mounting portion 32 toward the rim 30. In the example in Figure 3, 10 circular mounting holes 32h are formed at equal intervals in the circumferential direction of the hub mounting portion 32. Note that the configuration of the mounting holes 32h (position, shape, number, etc.) is not limited to the above and can be changed according to the design specifications.

[0024] The wheel 3 has multiple decorative holes 33h formed at equal intervals in the circumferential direction. In the example shown in Figure 3, ten oval-shaped decorative holes 33h are formed at equal intervals in the circumferential direction of the connecting portion 33. Note that the configuration of the decorative holes 33h (position, shape, number, etc.) is not limited to the above and can be changed according to the design specifications.

[0025] <Sensor> Sensor 10 is, for example, a piezoelectric element. A piezoelectric element is a piezoelectric element that generates a voltage when pressure is applied to it. A piezoelectric element generates a voltage in accordance with the strain caused by applying pressure to the piezoelectric material.

[0026] Multiple sensors 10 are provided. Each of the multiple sensors 10 is mounted on the wheel 3 in a location corresponding to at least two of the multiple mounting holes 32h. The multiple sensors 10 are arranged with spacing in the circumferential direction. When viewed from the axial direction of the wheel 3, the sensors 10 are positioned on a virtual line K that passes through the center of the mounting holes 32h and extends radially.

[0027] Figure 4 is a cross-sectional view showing an example of the mounting position of the sensor 10 on the second curved surface 33b of the wheel 3 of the embodiment. Referring also to Figure 4, in a cross-sectional view including the rotation axis of the wheel 3, a portion of the surface of the connecting portion 33 has a first curved surface 33a located at the outermost position in the axial direction and curving radially outward, and a second curved surface 33b located second from the outermost position in the axial direction and curving radially inward or outward. In the example of Figure 4, the second curved surface 33b is connected to the first curved surface 33a and curves radially inward. The sensor 10 is positioned on the second curved surface 33b.

[0028] In the example shown in Figure 4, the piezoelectric element, which is the sensor 10, is formed in a flat plate shape. The flat-shaped piezoelectric element (hereinafter also referred to as the "flat plate element") is directly attached to the second curved surface 33b via adhesive 40.

[0029] Figure 5 is a front view showing an example of the mounting positions of multiple sensors 10 on the wheel 3 of the embodiment. Referring also to Figure 5, the multiple sensors 10 are arranged at different intervals (unequal intervals) in the circumferential direction. In the example in Figure 5, in the wheel 3, 10 circular mounting holes 32h are formed at equal intervals in the circumferential direction of the hub mounting portion 32, and 6 oval decorative holes 33h are formed at equal intervals in the circumferential direction of the connecting portion 33. In the example in Figure 5, four sensors 10 are arranged at unequal intervals in the circumferential direction on the second curved surface 33b, and are also positioned on a virtual line K passing through the centers of the four corresponding mounting holes 32h (shown as (2), (4), (7), (9) in Figure 5).

[0030] Figure 6 is a front view showing another example of the mounting positions of the multiple sensors 10 on the wheel 3 of the embodiment. Referring also to Figure 6, the multiple sensors 10 are arranged at equal intervals in the circumferential direction. In the example in Figure 6, eight circular mounting holes 32h are formed at equal intervals in the circumferential direction of the hub mounting portion 32 of the wheel 3, and four oval decorative holes 33h are formed at equal intervals in the circumferential direction of the connecting portion 33. In the example in Figure 6, the eight sensors 10 are arranged at equal intervals in the circumferential direction on the second curved surface 33b, and are also positioned on a virtual line K passing through the centers of the eight corresponding mounting holes 32h (shown in Figure 6 (1) to (8)).

[0031] Multiple sensors 10 can be mounted in various locations, not limited to the equally spaced arrangement described above. Referring also to Figure 3, multiple sensors 10 can be mounted in the annular region A1, which includes the entire second curved surface 33b, excluding the decorative hole 33h, when viewed from the axial direction of the wheel 3.

[0032] Furthermore, in order to identify which of the multiple fastening points has loosened, it is preferable that the sensor 10 be mounted on the side of the target mounting hole 32h rather than the midpoint between the target mounting hole 32h and the adjacent mounting hole 32h in the circumferential direction. For example, it is preferable that the sensor 10 corresponding to each mounting hole 32h be mounted in a sector-shaped region A2 that is sandwiched between two imaginary lines K that pass through the midpoint between the target mounting hole 32h and the adjacent mounting hole 32h in the circumferential direction and extend along the radial direction, when viewed from the axial direction of the wheel 3.

[0033] Furthermore, since the sensitivity of the sensor 10 decreases as it moves away from the hub mounting portion 32 in the radial direction, it is preferable that the mounting location of the sensor 10 be in an area excluding the outermost edge of the disc 31. For example, it is more preferable that the sensor 10 corresponding to each mounting hole 32h be mounted in the arc-shaped region A3, excluding the radial inner and outer ends of the sector-shaped region A2, when viewed from the axial direction of the wheel 3.

[0034] For example, when the wheel is in contact with the ground and rotating, the wheel 3 undergoes elastic deformation not only in the lower portion where the vehicle load is applied, but also in other areas. For example, multiple sensors 10 (piezoelectric elements) may be intermittently arranged at a constant period in the circumferential direction of the wheel 3. This allows for efficient power generation not only by the piezoelectric elements located in the lower portion in contact with the ground, but also by the piezoelectric elements located elsewhere.

[0035] <Judgment part> Referring to Figures 1 and 2, the determination unit 11 is attached to the wheel 3. For example, the determination unit 11 may be positioned in the rim drop portion of the rim 30 of the wheel 3. The rim drop portion is a continuous concave recess extending in the circumferential direction on the outer circumferential surface of the rim 30 of the wheel 3. Note that the arrangement of the determination unit 11 is not limited to the above and can be changed according to the design specifications.

[0036] For example, the determination unit 11 may be mounted on a sensing (safety) wheel board, which is a control board. The determination unit 11 is an example of a processing unit, such as a CPU (Central Processing Unit). Although not shown in the figures, the sensing (safety) wheel board is equipped with storage units such as RAM (Random Access Memory), ROM (Read Only Memory), and combinations thereof, as well as input / output units that are interface circuits with other devices.

[0037] The determination unit 11 determines that there is an abnormality in the wheel 3 when the voltage generated by the piezoelectric element falls outside the threshold. When the voltage generated by the piezoelectric element falls outside the threshold, this includes both cases: when the voltage generated by the piezoelectric element exceeds the upper threshold limit (upper limit of the threshold range), and when the voltage generated by the piezoelectric element falls below the lower threshold limit (lower limit of the threshold range).

[0038] For example, the determination unit 11 operates using the power generated by the piezoelectric element. For example, the determination unit 11 determines that there is an abnormality in the wheel 3 when the voltage generated by the piezoelectric element deviates from a threshold due to deformation caused by the rotation of the wheel 3. For example, when there is input to the wheel 3 while the vehicle is running, the determination unit 11 determines whether the wheel 3 is normal or abnormal (for example, a loose nut). This determination is made, for example, based on the strain distribution of the wheel 3.

[0039] For example, the determination unit 11 determines an abnormality while the vehicle 2 equipped with the wheel 3 is in motion. For example, the determination unit 11 determines looseness in the fastening portion of the wheel 3 while it is in motion. For example, the determination unit 11 may determine an abnormality while the vehicle 2 is traveling at a low speed below a predetermined speed. Note that the speed at which the determination unit 11 determines an abnormality in the vehicle 2 is not limited to the above and can be changed according to the design specifications.

[0040] The determination unit 11 compares the data detected by each of the multiple sensors 10 and determines the position corresponding to the sensor 10 that detected the data that changed the most relative to a predetermined standard as the position where the wheel 3 malfunction occurred. In this embodiment, the sensor 10 is a piezoelectric element. The determination unit 11 compares the voltages generated by each of the multiple piezoelectric elements and determines the position corresponding to the piezoelectric element that detected the voltage that changed the most relative to a predetermined standard as the position where the wheel 3 malfunction (for example, a loose nut) occurred.

[0041] The following two patterns can be described for "determining the location corresponding to the piezoelectric element that detected the greatest change in voltage relative to a predetermined standard as the location where the abnormality of wheel 3 occurred." One pattern involves setting a threshold value for the steady state after tightening a nut into the mounting hole 32h of the wheel 3, and determining the position corresponding to the piezoelectric element whose voltage has increased or decreased by a predetermined amount relative to the steady state threshold as the position where an abnormality occurred in the wheel 3. The second pattern involves monitoring the power generation state of the piezoelectric elements around the entire circumference of the wheel 3, detecting the amount of change compared to other parts, and determining the location corresponding to the piezoelectric element with the largest change as the location where the abnormality of the wheel 3 occurred.

[0042] In the second pattern, if loosening occurs evenly around the entire circumference of the wheel 3, it is difficult to determine the location where the abnormality of the wheel 3 occurred. Therefore, from the standpoint of improving reliability, it is preferable to determine the location where the abnormality of the wheel 3 occurred by combining the first and second patterns.

[0043] <Energy Storage Section> The power storage unit 12 is attached to the wheel 3. For example, the power storage unit 12 may be located on the rim drop portion of the wheel 3. For example, the power storage unit 12 may be located near the determination unit 11. Note that the arrangement of the power storage unit 12 is not limited to the above and can be changed according to the design specifications.

[0044] The energy storage unit 12 stores the power generated by the piezoelectric element. For example, the energy storage unit 12 may be mounted on the power charging / discharging board of the sensing (safety) wheel substrate. For example, the energy storage unit 12 is composed of a secondary battery such as a lithium-ion secondary battery or a nickel-metal hydride secondary battery. However, the configuration of the energy storage unit 12 is not limited to the above and can be changed according to the design specifications.

[0045] <Communication Department> The transmitter 13 is attached to the wheel 3. For example, the transmitter 13 may be positioned on the drop portion of the rim 30 of the wheel 3. For example, the transmitter 13 may be positioned near the energy storage unit 12. Note that the arrangement of the transmitter 13 is not limited to the above and can be changed according to the design specifications.

[0046] The transmitting unit 13 operates using the power stored in the energy storage unit 12 and transmits an abnormality. For example, the transmitting unit 13 may be mounted on an abnormality signal transmitter on a sensing (safety) wheel substrate. For example, the signal transmitted by the abnormality signal transmitter is received by an abnormality signal receiver on the vehicle body via wireless communication. For example, the signal received by the abnormality signal receiver is used for vehicle operation.

[0047] For example, an abnormal signal transmitter receives a signal related to fluctuations in the voltage distribution. For example, the fluctuation in the voltage distribution is a voltage fluctuation due to the strain of wheel 3. For example, the processing to capture the fluctuation in the voltage distribution may be performed by frequency conversion (for example, conversion by frequency analysis based on the rotational speed of wheel 3). For example, the threshold value when making a judgment based on voltage fluctuations may be set based on changes in the amplitude of frequencies other than the vehicle's driving speed.

[0048] For example, the abnormal signal transmitter (corresponding to the transmitter unit 13) may be positioned 180° opposite to the valve location on the wheel 3 (in other words, on the radially opposite side of the wheel 3). This improves the weight balance of the wheel 3 compared to the case where the abnormal signal transmitter is positioned near the valve location on the wheel 3. Note that the arrangement of the abnormal signal transmitter is not limited to the above and can be changed according to the design specifications.

[0049] <Abnormality determination method> Figure 7 is a flowchart showing an example of an abnormality detection method in the embodiment. Referring also to Figure 7, the abnormality detection method includes a rotation step of rotating a wheel 3, which has a plurality of mounting holes 32h formed at equal intervals in the circumferential direction, and a determination step of comparing the data detected by each of a plurality of sensors 10, which are attached to parts of the wheel 3 corresponding to at least two of the plurality of mounting holes 32h and are arranged at intervals in the circumferential direction, and determining that the position corresponding to the sensor 10 that detected the data that changed the most with respect to a predetermined standard is the position where the abnormality of the wheel 3 occurred.

[0050] For example, in step S1, the wheel 3 is rotated. For example, the abnormality detection system 1 rotates the wheel 3 by driving the vehicle 2 equipped with the wheel 3. After step S1, the system proceeds to step S2.

[0051] For example, in step S2, it is determined whether the voltage generated by the piezoelectric element attached to the wheel 3 has fallen outside the threshold. For example, the determination unit 11 determines whether the wheel 3 is normal or abnormal (for example, the nuts are loose) based on the fluctuation in the voltage distribution due to the strain of the wheel 3.

[0052] If it is determined in step S2 that the voltage generated by the piezoelectric element attached to wheel 3 has fallen outside the threshold (YES in step S2), the process proceeds to step S3. On the other hand, if it is determined in step S2 that the voltage generated by the piezoelectric element attached to wheel 3 has not fallen outside the threshold (NO in step S2), the process returns to the step before S2.

[0053] For example, in step S3, an abnormality in wheel 3 is determined. For example, a loose nut is determined as an abnormality in wheel 3. After step S3, the process proceeds to step S4.

[0054] For example, in step S4, the location where the abnormality of the wheel 3 occurred is identified. For instance, the voltages generated by each of the multiple piezoelectric elements are compared, and the location corresponding to the piezoelectric element that detected the voltage that changed the most relative to a predetermined standard is determined to be the location where the abnormality of the wheel 3 occurred (for example, the location where the nut loosened). The process for detecting an anomaly is completed following the above flow.

[0055] <FEM analysis results, a preliminary verification of loosening detection> Figure 8 shows an example of FEM analysis results, which are a preliminary verification of loosening detection in the embodiment. In Figure 8, the fastening conditions for the FEM analysis were set to two conditions: full circumferential constraint on the wheel 3 (no loosening) and one nut loosening (loosening present). The analysis was conducted from three directions: the front of the disc 31, the R section (curved surface), and the mounting surface. The amount of deformation of the wheel 3 was compared when the FEM analysis was performed under each of these conditions. In order to determine the optimal detection position for nut loosening detection using a piezoelectric element, the steady state (corresponding to no fastening loosening) and the loosening state were reproduced using the FEM analysis, and locations with large changes in stress were identified.

[0056] The inventors' analysis confirmed that when loosening occurs, the deformation of the wheel 3 increases in areas other than those with constraint. Stress comparison results from FEM analysis showed that when nut loosening occurs, a large change in stress is observed in the first curved surface 33a and the second curved surface 33b of the disc 31.

[0057] As described above, since the wheel 3 of this embodiment is mounted on the vehicle 2, when the wheel is in contact with the ground and rotating, the wheel 3 rotates while receiving a load. As the wheel 3 rotates, stress (strain) is generated. For example, the stress distribution (strain distribution) of the wheel 3 changes between a state with no nut loosening (steady state) and a state with nut loosening (abnormal). This change can be used to determine nut loosening. For example, the data from the FEM analysis results described above may be acquired in advance, and nut loosening may be determined based on this acquired data.

[0058] Incidentally, conventional technology involves detecting abnormalities such as loosening of nuts, which are the fastening points of a wheel, using vibration sensors (for example, acceleration sensors) attached to the wheel. However, with such technology, it is not possible to determine which of the multiple fastening points has loosened (the location where the abnormality occurred). Furthermore, since vibration sensors measure acceleration, when considered on a real vehicle basis, they are highly likely to easily pick up external disturbance factors. Therefore, the accuracy of loosening detection may be insufficient.

[0059] In contrast, in this embodiment, the abnormality of the wheel 3 is determined when the voltage generated by the piezoelectric element deviates from the threshold, thus reducing the likelihood of picking up external disturbances. Therefore, the accuracy of the loosening detection is unlikely to be insufficient.

[0060] <Effects and Effects> As described above, the abnormality determination system 1 of the above embodiment includes a wheel 3 having a plurality of mounting holes 32h formed at equal intervals in the circumferential direction, a plurality of sensors 10 attached to parts of the wheel 3 corresponding to at least two of the plurality of mounting holes 32h and arranged at intervals in the circumferential direction, and a determination unit 11 that compares the data detected by each of the plurality of sensors 10 and determines that the position corresponding to the sensor 10 that detected the data that changed the most with respect to a predetermined standard is the position where an abnormality occurred in the wheel 3. With this configuration, the location where an abnormality occurred in the wheel 3 can be determined based on the detection data from multiple sensors 10 attached to the wheel 3. For example, the location where the abnormality of wheel 3 occurred can be determined as the location where the loosening of the fastening part of wheel 3 occurred.

[0061] In the above embodiment, the sensor 10 is positioned on a virtual line K that passes through the center of the mounting hole 32h and extends radially when viewed from the axial direction of the wheel 3. With this configuration, the location where an abnormality (such as a loose nut) occurs in the mounting hole 32h can be determined more effectively compared to the case where the sensor 10 is positioned at a location offset from the imaginary line K when viewed from the axial direction.

[0062] In the above embodiment, the wheel 3 includes a disc 31 provided inside a cylindrical rim 30. The disc 31 includes a hub mounting portion 32 having a plurality of mounting holes 32h and being attached to a vehicle-side hub, and a connecting portion 33 extending from the hub mounting portion 32 toward the rim 30. In a cross-sectional view including the rotation axis of the wheel 3, a portion of the surface of the connecting portion 33 has a first curved surface 33a located at the outermost position in the axial direction and curving toward the radially outward direction, and a second curved surface 33b located second from the outermost position in the axial direction and curving toward the radially inward or outward direction. The sensor 10 is positioned on the second curved surface 33b. This configuration reduces the risk of interference with vehicle-side components compared to the case where the sensor 10 is positioned on the first curved surface 33a.

[0063] In the above embodiment, the sensor 10 is a piezoelectric element. The determination unit 11 compares the voltages generated by each of the multiple piezoelectric elements and determines that the position corresponding to the piezoelectric element that detected the voltage that changed the most relative to a predetermined standard is the position where the abnormality of the wheel 3 occurred. With this configuration, the location where an abnormality in the wheel 3 occurred can be determined based on the voltage generated by multiple piezoelectric elements attached to the wheel 3.

[0064] In the above embodiment, the piezoelectric element is formed in a flat plate shape. With this configuration, compared to the case where the piezoelectric element is formed in a curved shape (e.g., an arc shape), the rate of change of the voltage of the piezoelectric element when an abnormality occurs is larger, so the location where the abnormality of the wheel 3 occurs can be determined more effectively.

[0065] In the above embodiment, the piezoelectric element is directly attached to the second curved surface 33b via the adhesive 40. With this configuration, compared to the case where a piezoelectric element formed in a flat plate shape is attached to the second curved surface 33b via a gap-filling plate, the decrease in sensitivity of the piezoelectric element to deformation of the wheel 3 can be reduced, making it possible to more effectively determine the location where an abnormality in the wheel 3 has occurred.

[0066] In the above embodiment, the determination unit 11 is attached to the wheel 3 and operates using the power generated by the piezoelectric element. This configuration allows the system to be implemented within wheel 3.

[0067] In the above embodiment, the device further includes a power storage unit 12 attached to the wheel 3, which stores the power generated by the piezoelectric element. With this configuration, the power stored in the energy storage unit 12 can be utilized. For example, the constructed system would not require battery replacement. For instance, when detecting a loose nut, the piezoelectric element itself generates electricity, eliminating the need for battery replacement in system maintenance and reducing management workload.

[0068] In the above embodiment, the system further includes a transmitter 13 that is attached to the wheel 3, operates using the power stored in the power storage unit 12, and transmits an abnormality. With this configuration, an abnormality can be detected using the power stored in the energy storage unit 12.

[0069] In the above embodiment, the determination unit 11 determines an abnormality while the vehicle equipped with the wheel 3 is in motion. This configuration allows for the detection of abnormalities while the vehicle is in motion. For example, if a loose nut is detected at a low speed, the vehicle can be safely stopped, allowing for inspection and other verification work to be carried out.

[0070] In the above embodiment, the determination unit 11 determines the loosening of the fastening portion of the wheel 3 during driving. With this configuration, it is possible to determine that an abnormality in wheel 3 is the loosening of the fastening portion of wheel 3 during driving.

[0071] The abnormality determination method of the above embodiment includes a rotation step of rotating a wheel 3 having a plurality of mounting holes 32h formed at equal intervals in the circumferential direction, and a determination step of comparing data detected by each of a plurality of sensors 10 that are attached to parts of the wheel 3 corresponding to at least two of the plurality of mounting holes 32h and are arranged at intervals in the circumferential direction, and determining that the position corresponding to the sensor 10 that detected the data that changed the most with respect to a predetermined standard is the position where an abnormality occurred in the wheel 3. This method allows for the determination of the location where an abnormality occurred in the wheel 3 based on detection data from multiple sensors 10 attached to the wheel 3.

[0072] <Variation> Figure 9 is a cross-sectional view of a modified wheel of the embodiment, showing the mounting position of the piezoelectric element. As shown in Figure 9, in a cross-sectional view including the rotation axis of the wheel, a portion of the surface of the connecting portion 133 may have a first curved surface 133a located at the outermost position in the axial direction and curving radially outward, a second curved surface 133b located second from the outermost position in the axial direction and curving radially outward, and a flat surface 133c located between the first curved surface 133a and the second curved surface 133b and inclined to be radially outward as it moves inward from the outermost position in the axial direction. For example, a piezoelectric element may be placed at least one of the first curved surface 133a, the second curved surface 133b, and the flat surface 133c.

[0073] In the above embodiment, the sensor was described as being positioned on a virtual line that passes through the center of the mounting hole and extends radially when viewed from the axial direction of the wheel, but the embodiment is not limited to this. For example, the sensor may be positioned at a location offset from the virtual line when viewed from the axial direction. The arrangement of the sensor can be changed according to the design specifications.

[0074] In the above embodiment, the wheel comprises a disc provided inside a cylindrical rim, the disc having a hub mounting portion with a plurality of mounting holes and attached to a vehicle-side hub, and a connecting portion extending from the hub mounting portion toward the rim, and in a cross-sectional view including the rotation axis of the wheel, a part of the surface of the connecting portion has a first curved surface located at the outermost axial position and curving toward the radially outward, and a second curved surface located second from the outermost axial position and curving toward the radially inward or outward, and the sensor is described as being arranged on the second curved surface, but is not limited to this. For example, the sensor may be arranged on the first curved surface. The arrangement of the sensor can be changed according to the design specifications.

[0075] In the above embodiment, the sensor is a piezoelectric element, and the determination unit compares the voltages generated by each of the multiple piezoelectric elements and determines the position corresponding to the piezoelectric element that detected the greatest change in voltage relative to a predetermined standard as the position where the wheel abnormality occurred. However, the embodiment is not limited to this. For example, the sensor may be a sensor other than a piezoelectric element. For example, the sensor may be a strain gauge. The form of the sensor can be changed according to the design specifications.

[0076] In the above embodiment, the piezoelectric element was described as being formed in a flat plate shape, but it is not limited to this. For example, the piezoelectric element may be formed in a curved shape (e.g., an arc shape). The shape of the piezoelectric element can be changed according to the design specifications.

[0077] In the above embodiment, the piezoelectric element was described as being directly attached to the second curved surface via an adhesive, but the embodiment is not limited to this. For example, a piezoelectric element formed in a flat plate shape may be attached to the second curved surface via a gap-filling plate. The mounting method of the piezoelectric element can be changed according to the design specifications.

[0078] In the above embodiment, the determination unit was described as being mounted on a wheel and operating using the power generated by the piezoelectric element, but it is not limited to this. For example, the determination unit may operate using power other than that generated by the piezoelectric element. For example, the determination unit may operate using power from a battery (not shown). The operating mode of the determination unit can be changed according to the design specifications.

[0079] In the above embodiment, an example was described in which a power storage unit, attached to the wheel and storing the electricity generated by the piezoelectric element, is further included, but the embodiment is not limited to this. For example, the power storage unit does not have to be attached to the wheel. For example, the abnormality detection system does not have to include a power storage unit. The installation method of the power storage unit can be changed according to the design specifications.

[0080] In the above embodiment, an example was described in which a transmitting unit is further provided, which is attached to the wheel, operates using power stored in the energy storage unit, and transmits an abnormality signal. However, the system is not limited to this example. For example, the transmitting unit does not need to be attached to the wheel. For example, the abnormality detection system does not need to include a transmitting unit. The installation method of the transmitting unit can be changed according to the design specifications.

[0081] In the above embodiment, the determination unit was described using an example where it determines an abnormality while a vehicle equipped with wheels is in motion, but it is not limited to this. For example, the determination unit does not need to determine an abnormality while a vehicle equipped with wheels is in motion. For example, the determination unit may determine an abnormality while a vehicle equipped with wheels is stopped. The manner in which the determination unit determines an abnormality can be changed according to the design specifications.

[0082] In the above embodiment, the determination unit was described as determining looseness of the wheel fastenings during driving, but it is not limited to this. For example, in addition to determining looseness of the wheel fastenings, the determination unit may also determine abnormal vibration of the wheel, or abnormalities in the hub or drive shaft. For example, since the voltage of the piezoelectric element changes due to the vehicle load, the determination unit may also determine abnormalities in the load, such as overloading. The manner in which the determination unit determines abnormalities can be changed according to the design specifications.

[0083] In the above embodiment, an example was given of a determination unit mounted on a sensing (safety) wheel board, which is a control board, that determines nut loosening, but it is not limited to this. For example, the determination unit may be applied to the determination of abnormalities related to air leak detection. For example, the determination unit may be used for wheel cracks, excessive wheel use, overload abnormalities, etc. For example, the application mode of the determination unit can be changed according to the design specifications.

[0084] In the above embodiment, the determination unit was described as being mounted on a wheel, but it is not limited to this. For example, the determination unit does not have to be mounted on a wheel. For example, the determination unit may be mounted on the vehicle body side of a vehicle equipped with a wheel. For example, the arrangement of the determination unit can be changed according to the design specifications.

[0085] In the above embodiment, the abnormality detection system was described using as an example a system that detects looseness in the fastening parts of wheels on cargo vehicles such as trucks as an abnormality, but it is not limited to this. For example, the wheels are not limited to large wheels used in commercial vehicles, but can also be applied to wheels for passenger cars or work vehicles. For example, the application method for wheels can be changed according to the design specifications.

[0086] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and additions, omissions, substitutions, and other modifications of the configuration are possible without departing from the spirit of the invention, and the above-described modifications can be combined as appropriate. [Examples]

[0087] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0088] [Examples] Regarding the abnormality detection system according to the present invention, tests were conducted to verify the reproducibility of determining the location where an abnormality occurred in the wheel based on the voltage of multiple piezoelectric elements attached to the wheel. Figure 10 is a cross-sectional view of the wheel in the embodiment, showing the mounting position of the piezoelectric element. In the example shown in Figure 10, piezoelectric elements were installed on the first curved surface (first R) and the second curved surface (second R) of the wheel's disc.

[0089] Figure 11 shows the change in voltage when the nuts of the piezoelectric elements installed on the first and second curved surfaces of the wheel in the embodiment loosen. In Figure 11, the scale of the graphs is the same. In the example shown in Figure 11, the change in voltage when the nut loosened was measured on the first curved surface (first radius on the mounting surface side) and the second curved surface (second radius on the design surface side) of the wheel in order to select the optimal mounting location.

[0090] On the mounting surface side, at the first rounded section, it was confirmed that the voltage waveform changes when the nut loosens, the voltage increases when a position adjacent to the attachment point loosens, and the waveform changes due to loosening at other positions. On the design surface side (R2), it was confirmed that the steady-state voltage was higher compared to the mounting surface side (R1), that the voltage decreased when the nut loosened, and that it was less susceptible to influences other than loosening of the adhesive position. The mounting surface side (1R) poses a risk of interference with vehicle components on the mounting side, and the design surface side (1R) also poses a risk of interference when mounting two wheels. In contrast, the design surface side (2R) has the advantage of not having any particular risk of interference. Therefore, it was determined that mounting to the design surface side (2R) is preferable for detecting nut loosening.

[0091] Figure 12 shows the change in voltage when the nuts of the flat plate element (flat-shaped piezoelectric element) and arc-shaped element (arc-shaped piezoelectric element) installed on the second curved surface of the wheel in the embodiment loosen. In Figure 12, the scale of the graphs is the same. In the example shown in Figure 12, a flat plate element and an arc-shaped element were attached to the same position and compared to select the optimal piezoelectric element on the second radius of the design surface.

[0092] The evaluation confirmed that the generated voltage decreased when the nuts coaxial with the element's mounting position loosened. On the other hand, no change in voltage was observed when nuts at adjacent positions, 90° angles, or diagonal positions loosened. Therefore, it was determined that attaching piezoelectric elements to all locations coaxial with the mounting holes on the 2R side of the design surface allows for accurate identification of nut loosening locations. The results of comparing and evaluating flat plate elements and arc-shaped elements showed that the voltage change rate during nut loosening was greater with flat plate elements. Therefore, it was determined that using flat plate elements is optimal for loosening detection.

[0093] Figure 13 is a cross-sectional view showing an example in which a flat plate element is directly bonded to the second curved surface of the wheel of the embodiment, and an example in which a gap-filling plate is used. The right side of Figure 13 shows an example where a flat plate element is directly bonded to the second curved surface via adhesive, while the left side of Figure 13 shows an example where a flat plate element is bonded to the second curved surface via adhesive and a gap-filling plate (an example using a gap-filling plate).

[0094] Figure 14 shows the change in voltage when the nut loosens in an example where a flat plate element is directly bonded to the second curved surface of the wheel of the embodiment and in an example where a gap-filling plate is used. The scale of the graphs is the same in Figure 14. Since the wheel is composed of curved surfaces and the flat plate element is plate-shaped, a gap-filling plate was used to fill the gaps that occur during bonding, and a comparative evaluation was conducted.

[0095] The evaluation results showed that using a gap-filling plate reduced the sensitivity of the piezoelectric element to wheel deformation, resulting in poor loosening detection performance. Therefore, it was determined that it is preferable to directly bond the flat plate element to the second curved surface via adhesive.

[0096] The present invention has been described in more detail above with reference to the examples, and in the examples, it was determined that it is reproducible to determine an abnormality in the wheel when the voltage generated by the piezoelectric element falls outside the threshold. [Explanation of symbols]

[0097] 1…Anomaly detection system 2…Vehicles 3... Wheels 10...Sensor 11...Judgment section 12…Energy storage unit 13…Transmission Unit 30...rim 31… Disc 32...Hub mounting section 32h…Mounting holes 33...Connection part 33a...First curved surface 33b...Second curved surface 40…Adhesive 133...Connection part 133a...First curved surface 133b...Second curved surface K...virtual line

Claims

1. A wheel having multiple mounting holes formed at equal intervals in the circumferential direction, Multiple sensors are attached to the wheel at locations corresponding to at least two of the multiple mounting holes, and are arranged at intervals in the circumferential direction. The system includes a determination unit that compares the data detected by each of the multiple sensors and determines that the position corresponding to the sensor that detected the data that changed the most with respect to a predetermined standard is the position where the wheel abnormality occurred. An anomaly detection system.

2. The sensor is positioned on a virtual line that passes through the center of the mounting hole and extends radially when viewed from the axial direction of the wheel. An anomaly detection system according to claim 1.

3. The wheel comprises a disc provided inside a cylindrical rim, The disc comprises a hub mounting portion having the plurality of mounting holes and being attached to the vehicle-side hub, and a connecting portion extending from the hub mounting portion toward the rim, In a cross-sectional view including the rotation axis of the wheel, a portion of the surface of the connecting portion has a first curved surface located at the outermost position in the axial direction and curving outward in the radial direction, and a second curved surface located second from the outermost position in the axial direction and curving inward or outward in the radial direction. The sensor is arranged on the second curved surface, The abnormality detection system according to claim 2.

4. The aforementioned sensor is a piezoelectric element, The determination unit compares the voltages generated by each of the plurality of piezoelectric elements and determines that the position corresponding to the piezoelectric element that shows the greatest change in voltage relative to a predetermined standard is the position where the wheel malfunction occurred. The abnormality detection system according to claim 3.

5. The piezoelectric element is formed in a flat plate shape. The abnormality detection system according to claim 4.

6. The piezoelectric element is directly attached to the second curved surface via an adhesive. The abnormality detection system according to claim 5.

7. The determination unit is attached to the wheel and operates using the power generated by the piezoelectric element. An anomaly detection system according to any one of claims 4 to 6.

8. The wheel is further equipped with a power storage unit that stores the electricity generated by the piezoelectric element. An anomaly detection system according to any one of claims 4 to 6.

9. The system further comprises a transmitting unit attached to the wheel, which operates using the power stored in the power storage unit and transmits the abnormality. The abnormality detection system according to claim 8.

10. The determination unit determines the abnormality while the vehicle equipped with the wheel is in motion. An anomaly detection system according to any one of claims 1 to 6.

11. The determination unit determines the loosening of the fastening portion of the wheel during driving. An anomaly detection system according to any one of claims 1 to 6.

12. A rotation process in which a wheel having multiple mounting holes formed at equal intervals in the circumferential direction is rotated, The method includes a determination step of comparing data detected by each of a plurality of sensors, each attached to a portion of the wheel corresponding to at least two of the plurality of mounting holes and arranged at intervals in the circumferential direction, and determining that the position corresponding to the sensor that detected the data that changed the most with respect to a predetermined standard is the position where the abnormality of the wheel occurred. Abnormality determination method.

Images