Tire information detection device

Abstract

Provided is a tire information detecting device capable of determining the installation state of a sensor module installed on a pneumatic tire on the basis of a measurement value supplied from the sensor module and accurately detecting tire information. A tire information detecting device 10 detects tire information including at least one of tire wear, tire deformation, road surface condition, tire ground contact condition, presence or absence of tire failure, tire running history, and tire load condition. The tire information detecting device 10 comprises: at least one sensor module 20 disposed on an inner surface of a tire; and a determination unit 15 for determining the installation state of the sensor module 20 on the basis of a measurement value supplied by the sensor module 20.

Description

Technical Field

[0001] The present invention relates to a tire information detection device, and more particularly, to a tire information detection device that determines the attachment state of a sensor module based on measurement values supplied from a sensor module installed in a pneumatic tire and enables accurate detection of tire information.

Background Art

[0002] In a pneumatic tire, for example, an acceleration sensor is installed inside the tire to measure acceleration, and tire information (wear state of the tread portion) is evaluated based on the measurement value (see, for example, Patent Document 1). When installing a sensor inside the tire in this way, it is necessary to confirm whether the sensor is attached to the correct position with respect to the tire and is functioning normally. However, the attachment state of the sensor is not determined based on the measurement value measured by the sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a tire information detection device that determines the attachment state of a sensor module based on measurement values supplied from a sensor module installed in a pneumatic tire and enables accurate detection of tire information.

Means for Solving the Problems

[0005] In order to achieve the above object, the tire information detection device of the present invention is a tire information detection device that detects tire information including at least one of tire wear, tire deformation, road surface condition, tire contact state, presence or absence of tire failure, tire driving history, and tire load state. It includes at least one sensor module arranged on the inner surface of the tire, An element mounted on the sensor module that generates a voltage based on the deformation of the tread portion during tire rotation, a voltage detection unit that detects the voltage generated by the element, a storage area that stores waveform data over time of the voltage detected by the voltage detection unit, an arithmetic unit that calculates the symmetry of the waveform data, which is an index value of the mounting state of the sensor module, from the waveform data stored in the storage area, and the and a determination unit that determines the attachment state of the sensor module based on the measurement value supplied from the sensor module. , a determination unit determines the mounting state of the sensor module based on the symmetry of the waveform data calculated by the arithmetic unit It is characterized by this.

Effect of the Invention

[0006] In the present invention, since it includes at least one sensor module arranged on the inner surface of the tire and a determination unit that determines the attachment state of the sensor module based on the measurement value supplied from the sensor module, the attachment state of the sensor module can be determined by using the measurement value supplied from the sensor module. Furthermore, tire information can be detected in a state where the sensor module is functioning normally.

[0007] In the tire information detection device of the present invention, it preferably has an element that generates a voltage based on the deformation of the tread portion during tire rotation and is mounted on the sensor module, a voltage detection unit that detects the voltage generated by the element, a storage area that stores the waveform data over time of the voltage detected by the voltage detection unit, and a calculation unit that calculates the symmetry of the waveform data that becomes an index value of the attachment state of the sensor module from the waveform data stored in the storage area. The determination unit preferably determines the attachment state of the sensor module based on the symmetry of the waveform data calculated by the calculation unit. The voltage generated by the element based on the deformation of the tread portion during tire rotation has little noise and can be measured and analyzed. Such a voltage is a suitable effective index for determining the attachment state of the sensor module.

[0008] The calculation unit extracts a waveform including a first peak point and a second peak point formed on both sides of the baseline of the waveform data, calculates a line segment SO and a line segment OF from an intersection point O where a line connecting the first peak point and the second peak point intersects the baseline of the waveform data, a start point S of the waveform, and an end point F of the waveform, and the determination unit preferably determines that the mounting state of the sensor module is good when the ratio of the shorter line segment to the longer line segment among the line segment SO and the line segment OF is 0.4 to 1.0. Thereby, the determination accuracy of the mounting state of the sensor module can be improved.

[0009] The calculation unit extracts a waveform including a first peak point and a second peak point formed on both sides of the baseline of the waveform data, calculates an absolute difference value |P1 - B| between the value P1 of the first peak point and the value B of the baseline of the waveform data and an absolute difference value |B - P2| between the value B of the baseline of the waveform data and the value P2 of the second peak point, and the determination unit preferably determines that the mounting state of the sensor module is good when the ratio |P1 - B| / |B - P2| of the absolute difference value |P1 - B| to the absolute difference value |B - P2| is 0.2 to 5.0. Thereby, the determination accuracy of the mounting state of the sensor module can be improved.

[0010] The calculation unit extracts a waveform including a first peak point and a second peak point formed on both sides of the baseline of the waveform data, calculates an intersection point O where a line connecting the first peak point and the second peak point intersects the baseline of the waveform data, and areas A1 and A2 of the waveform on both sides of a waveform central axis perpendicular to the baseline of the waveform data passing through the intersection point O, and the determination unit preferably determines that the mounting state of the sensor module is good when the ratio of the smaller area to the larger area among the area A1 and the area A2 is 0.4 to 1.0. Thereby, the determination accuracy of the mounting state of the sensor module can be improved.

[0011] The calculation unit calculates an index value of voltage change from the waveform data stored in the storage area, and it is preferable that the determination unit compares the index value of voltage change calculated by the calculation unit with the reference information to determine the progress state of wear of the tread portion. Thereby, the attachment state of the sensor module can be determined, and the progress state of wear in the tread portion can be accurately detected.

[0012] It has a speed detection unit that detects the vehicle speed or the tire rotation speed. The storage area stores the waveform data of the voltage over time detected by the voltage detection unit together with the vehicle speed or the tire rotation speed detected by the speed detection unit. The calculation unit calculates an index value of voltage change from the waveform data in a predetermined speed range stored in the storage area, and it is preferable that the determination unit compares the index value of voltage change calculated by the calculation unit with the reference information corresponding to the predetermined speed range to determine the progress state of wear of the tread portion. Thereby, the attachment state of the sensor module can be determined, and the progress state of wear in the tread portion can be accurately detected.

[0013] It is preferable that the calculation unit calculates the peak amplitude value between the maximum value P1 and the minimum value P2 in the waveform data as the index value of voltage change. Thereby, the determination accuracy of the progress state of wear in the tread portion can be improved.

[0014] It has a speed detection unit that detects the vehicle speed or the tire rotation speed. The storage area stores the waveform data of the voltage over time detected by the voltage detection unit together with the vehicle speed or the tire rotation speed detected by the speed detection unit. The calculation unit calculates the excess frequency with respect to a predetermined threshold value from the waveform data in a predetermined speed range and a predetermined time stored in the storage area, and it is preferable that the determination unit determines the progress state of wear of the tread portion based on the excess frequency with respect to the predetermined threshold value calculated by the calculation unit. Thereby, the progress state of wear in the tread portion can be accurately detected.

[0015] It preferably has a pressure detection unit for detecting the air pressure inside the tire, and the calculation unit corrects waveform data or a predetermined threshold value based on the air pressure detected by the pressure detection unit. Thereby, the determination accuracy of the wear progress state in the tread portion can be improved.

[0016] The determination unit preferably executes at least two determination operations and finally determines the wear progress state of the tread portion based on the results of these determination operations. Thereby, the occurrence of sudden errors in the final determination result can be suppressed, and the determination accuracy of the wear progress state in the tread portion can be improved.

[0017] The sensor module preferably includes at least an element and a voltage detection unit, and the sensor module is fixed to the inner surface of the tire via a container into which the sensor module is inserted.

[0018] The container is joined to the inner surface of the tire via an adhesive layer. As the roughness of the inner surface of the tire, it is preferable that the arithmetic mean height Sa is in the range of 0.3 μm to 15.0 μm and the maximum height Sz is in the range of 2.5 μm to 60.0 μm. Thereby, the adhesion area between the inner surface of the tire and the adhesive layer can be increased, and the adhesiveness between the inner surface of the tire and the container can be effectively improved. The roughness of the inner surface of the tire is measured in accordance with ISO25178. The arithmetic mean height Sa is the average of the absolute values of the differences in height of each point with respect to the average plane of the surface, and the maximum height Sz is the height direction distance from the highest point to the lowest point on the surface.

[0019] It is preferable that the width Lc1 of the opening of the container and the inner width Lc2 of the bottom surface of the container satisfy the relationship Lc1 < Lc2. Thereby, since the width Lc1 of the opening becomes relatively small, it is possible to prevent the sensor module housed in the container from falling off, and it is possible to achieve both workability during insertion of the sensor module and the holding property of the container.

[0020] It is preferable that the width Lc1 of the opening of the container and the maximum width Lsm of the sensor module satisfy the relationship of 0.10 ≦ Lc1 / Lsm ≦ 0.95. By appropriately setting the ratio of the width Lc1 of the opening to the maximum width Lsm of the sensor module, it is possible to effectively prevent the sensor module from falling off, and improve the workability when inserting the sensor module and the holding property of the container.

[0021] It is preferable that the width Lc1 of the opening of the container, the inner width Lc2 of the bottom surface of the container, the width Ls1 of the upper surface of the sensor module, and the width Ls2 of the lower surface of the sensor module satisfy the relationship of Lc1 < Ls1 ≦ Ls2 ≦ Lc2. By appropriately setting the widths of the container and the sensor module, it is possible to effectively prevent the sensor module from falling off.

[0022] The average thickness of the container is preferably 0.5 mm to 5.0 mm. Thereby, it is possible to improve the workability when inserting the sensor module, the holding property of the container, and the fracture resistance of the container in a well-balanced manner.

[0023] The ratio of the height Hc of the container in the state where the sensor module is inserted to the height Hs of the sensor module is preferably in the range of 0.5 to 1.5. Thereby, it is possible to effectively prevent the sensor module from falling off.

[0024] The elongation at break EB of the rubber constituting the container is 50% to 900%, and the modulus at 300% elongation of the rubber constituting the container is preferably 2 MPa to 15 MPa. Thereby, it is possible to improve the workability when inserting the sensor module, the holding property of the container, and the fracture resistance of the container in a well-balanced manner. Note that the elongation at break and the modulus at 300% elongation of the rubber constituting the container are measured in accordance with JIS-K6251.

[0025] The container is preferably arranged on the inner side in the tire width direction from the ground end. Thereby, the sensor module inserted into the container can accurately acquire tire information.

[0026] The above element is preferably a piezoelectric element. Since the piezoelectric element generates a voltage based on the deformation of the tread portion during tire rotation, it is less likely to be affected by noise compared to an acceleration sensor or the like, and precise detection is possible.

[0027] In the present invention, the ground end is the end in the tire axial direction when the tire is mounted on a regular rim, filled with the regular internal pressure, placed vertically on a plane, and a regular load is applied. The "regular rim" is the rim defined for each tire in the standard system including the standard on which the tire is based. For example, in the case of JATMA, it is the standard rim; in the case of TRA, it is the "Design Rim"; or in the case of ETRTO, it is the "Measuring Rim". The "regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. In the case of JATMA, it is the maximum air pressure; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; in the case of ETRTO, it is the "INFLATION PRESSURE". However, when the tire is a passenger car tire, it is 250 kPa. The "regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. In the case of JATMA, it is the maximum load capacity; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; in the case of ETRTO, it is the "LOAD CAPACITY". However, when the tire is a passenger car tire, it is a load corresponding to 80% of the above load.

Brief Description of the Drawings

[0028]

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DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a tire information detection device according to an embodiment of the present invention.

[0030] When detecting the tire information of the tire T (see, for example, FIG. 9), the tire information detection device 10 determines whether the mounting state of the sensor module 20 is good based on the measurement values supplied from the sensor module 20. Further, the tire information detection device 10 detects the tire information of the tire T based on the measurement values supplied from the sensor module 20.

[0031] The tire information is a group consisting of tire wear, tire deformation, road surface condition, tire contact state, presence or absence of tire failure, tire driving history, and tire load state. At least one can be selected from this group and used as tire information. The tire information is not limited to the group described above and may be added as appropriate. Hereinafter, the tire information detection device 10 that detects the wear of the tire T (the progress state of the wear of the tread portion 1) as tire information will be described.

[0032] As shown in FIG. 1, the tire information detection device 10 includes an element 11 that is mounted on the sensor module 20 and generates a voltage based on the deformation of the tread portion 1 during tire rotation, a voltage detection unit 12 that detects the voltage generated by the element 11, a storage area 13 that stores the waveform data of the voltage detected by the voltage detection unit 12 over time, an arithmetic unit 14 that calculates the symmetry of the waveform data that becomes an index value of the mounting state of the sensor module 20 from the waveform data stored in the storage area 13, and a determination unit 15 that determines the mounting state of the sensor module 20 based on the symmetry of the waveform data calculated by the arithmetic unit 14.

[0033] In addition to the voltage detection unit 12, the tire information detection device 10 may have a speed detection unit 16 that detects the vehicle speed or the tire rotation speed, an air pressure detection unit 17 that detects the air pressure inside the tire, or a temperature detection unit 18 that detects the temperature inside the tire. In addition, devices such as an input device, an output device, and a display can be appropriately added to the tire information detection device 10.

[0034] In the tire information detection device 10, the storage area 13, the arithmetic unit 14, and the determination unit 15 function as a data processing device 19. This data processing device 19 processes data input from a detection unit represented by the voltage detection unit 12. The data input to the data processing device 19 may be either wired or wireless.

[0035] The sensor module 20 includes at least the element 11 and the voltage detection unit 12 in order to acquire tire information. Further, the sensor module 20 can be equipped with sensors so as to appropriately include the air pressure detection unit 17 and the temperature detection unit 18 together with the element 11 and the voltage detection unit 12.

[0036] The element 11 is a component of the voltage detection unit 12 and is included in the voltage detection unit 12. The element 11 is not particularly limited as long as it generates a voltage in proportion to the deformation amount (deformation energy) of the tread portion 1 during tire rotation. As such an element 11, for example, a piezoelectric element can be used. This piezoelectric element is arranged so that the element directly or indirectly contacts the inner surface of the tire, and is configured to be able to detect the deformation of the tread portion 1 by the element. The element indirectly contacting the inner surface of the tire means that, for example, the element contacts the inner surface of the tire through the housing of the sensor module 20, or the element is covered with a protective layer made of rubber or the like and the element contacts the inner surface of the tire through the protective layer. It means that the deformation of the tread portion 1 can be detected even if other members are interposed between the element and the inner surface of the tire. Since the piezoelectric element has a structure that generates a voltage based on the deformation of the tread portion 1 during tire rotation, noise is not easily introduced and precise detection is possible.

[0037] The voltage detection unit 12 is a potential sensor that detects the potential difference in the charged element 11. Since the voltage detection unit 12 includes the element 11 that generates voltage based on the deformation of the tread portion 1 during tire rotation, it is different from a strain sensor that detects strain. Also, the speed detection unit 16 may detect measurement data (vehicle speed) by a speedometer on the vehicle side, or may detect the tire rotation speed using a sensor capable of detecting the tire rotation speed. Further, a pressure sensor can be used as the air pressure detection unit 17, and a temperature sensor can be used as the temperature detection unit 18.

[0038] In the storage area 13, waveform data of the voltage detected by the voltage detection unit 12 over time is stored. Here, the storage area 13 can be configured by an external storage device such as a hard disk, an internal storage device such as a RAM, or a combination thereof. Figure 2 shows the waveform data stored in the storage area 13. In Figure 2, the vertical axis is voltage [V], the horizontal axis is elapsed time [μs], and waveform data for one rotation of the tire T is shown. While the tire T rotates, the waveform (voltage) reaches a peak (maximum or minimum value) when a point on the circumference of the tire T is located at the front end of contact with the ground and when it is located at the rear end of contact with the ground. Also, Figure 3 shows another example of the waveform data stored in the storage area 13. In Figure 3, the waveform data d1 is data when the tire T is new, and the waveform data d2 is data in a state where wear of the tread portion 1 of the tire T has progressed (late stage of wear). That is, as the wear of the tread portion 1 of the tire T progresses, the peak values of the voltage when located at the front end of contact with the ground and when located at the rear end of contact with the ground tend to increase. Note that the waveform data shown in Figures 2 and 3 is a representative example and is not limited thereto.

[0039] Further, when the tire information detection device 10 includes the speed detection unit 16, the memory area 13 stores the waveform data of the voltage detected by the voltage detection unit 12 together with the vehicle speed or the tire rotation speed detected by the speed detection unit 16. That is, in the memory area 13, the vehicle speed or the tire rotation speed and the waveform data of the voltage are associated and stored integrally. Further, when the tire information detection device 10 includes the air pressure detection unit 17 and the temperature detection unit 18, the memory area 13 stores the waveform data of the voltage detected by the voltage detection unit 12 together with the air pressure and the temperature detected by the air pressure detection unit 17 and the temperature detection unit 18. That is, in the memory area 13, the air pressure and the temperature and the waveform data of the voltage are associated and stored integrally.

[0040] When detecting the mounting state of the sensor module 20, the calculation unit 14 calculates the symmetry of the waveform data, which is an index value of the mounting state of the sensor module 20, from the waveform data stored in the memory area 13. At this time, the calculation unit 14 reads out the waveform data stored in the memory area 13, executes the calculation, and stores the index value of the mounting state of the sensor module 20 after the calculation in the memory area 13. Further, the calculation unit 14 can perform the calculation based on the waveform data for a plurality of rotations of the tire T, and waveform data for 5 or more rotations is preferable in order to prevent misjudgment.

[0041] Specifically, when calculating the symmetry of the waveform data, the arithmetic unit 14 extracts a waveform v including a first peak point p1 (the point with the maximum value in FIG. 2) and a second peak point p2 (the point with the minimum value in FIG. 2) formed on both sides of the baseline BL of the waveform data from the waveform data stored in the storage area 13, and performs any one of the following arithmetic processes (a) to (c). This baseline BL is a reference line for the numerical values in the waveform data and does not necessarily indicate zero as a numerical value (in FIG. 2, the value B of the baseline BL is 0 [V]). Also, the baseline BL may be an approximate line obtained by removing high-frequency noise and a gentle displacement trend (trend) by moving average processing. Note that the symmetry of the waveform data means that the waveform v1 and the waveform v2 are in a point-symmetric relationship with respect to the intersection point O and in a line-symmetric relationship with respect to the waveform center axis M, but it does not necessarily have perfect symmetry. (a) In the extracted waveform v, the arithmetic unit 14 calculates line segments SO and OF from the intersection point O where the line L connecting the first peak point p1 and the second peak point p2 intersects the baseline BL, the start point S of the waveform v, and the end point F of the waveform v. The arithmetic unit 14 calculates the ratio of the shorter line segment to the longer line segment among the line segments SO and OF. (b) In the extracted waveform v, the arithmetic unit 14 calculates the absolute difference |P1 - B| between the value P1 of the first peak point p1 and the value B of the baseline BL of the waveform data and the absolute difference |B - P2| between the value B of the baseline BL of the waveform data and the value P2 of the second peak point p2. The arithmetic unit 14 calculates the ratio |P1 - B| / |B - P2| of the absolute difference |P1 - B| to the absolute difference |B - P2|. (c) In the extracted waveform v, the arithmetic unit 14 calculates the intersection point O where the line L connecting the first peak point p1 and the second peak point p2 intersects the baseline BL, and the areas A1 of the waveform v1 and A2 of the waveform v2 (the areas of the hatched parts shown in FIG. 2) on both sides of the waveform center axis M perpendicular to the baseline BL passing through the intersection point O. The arithmetic unit 14 calculates the ratio of the smaller area to the larger area among the areas A1 and A2.

[0042] When detecting the wear of the tire T, the calculation unit 14 calculates an index value of the voltage change from the waveform data stored in the storage area 13. At this time, the calculation unit 14 can store the calculated index value in the storage area 13, and can also read out the stored index value to execute the calculation. Here, as the index value of the voltage change, the peak amplitude value between the maximum value and the minimum value in the waveform data or the area of the waveform data can be used. Further, the calculation unit 14 can read out two index values of the voltage change from the storage area 13 and calculate the change rate of one index value of the voltage change with respect to the other index value of the voltage change. The calculation unit 14 can be configured by, for example, a memory or a CPU.

[0043] In addition, when the tire information detection device 10 has the speed detection unit 16, when detecting the wear of the tire T, the calculation unit 14 calculates an index value of the voltage change from the waveform data within a predetermined speed range stored in the storage area 13. Here, the predetermined speed range is a speed range with a lower limit of -5 km / h and an upper limit of +5 km / h from an arbitrary speed [km / h]. The arbitrary speed can be set, for example, within the range of 30 km / h to 60 km / h.

[0044] Furthermore, when the tire information detection device 10 has the air pressure detection unit 17 and the temperature detection unit 18, when detecting the wear of the tire T, based on the air pressure detected by the air pressure detection unit 17 and the temperature detected by the temperature detection unit 18, the calculation unit 14 can correct the waveform data or the index value of the voltage change obtained from the waveform data. At this time, the calculation unit 14 reads out the waveform data or the index value of the voltage change stored in the storage area 13 to execute the correction, and stores the corrected waveform data or the index value of the voltage change in the storage area 13.

[0045] When determining the attachment state of the sensor module 20, the determination unit 15 determines the attachment state of the sensor module 20 based on the symmetry of the waveform data calculated by the calculation unit 14. Specifically, the determination unit 15 performs any one of the following determination processes (a) to (c). At this time, the determination unit 15 reads the symmetry index value of the waveform data from the storage area 13 and executes the determination. Note that the determination unit 15 may be configured to calculate the ratio of the shorter line segment to the longer line segment among the line segment SO and the line segment OF based on the line segment SO and the line segment OF calculated by the calculation unit 14. (a) When the calculation unit 14 calculates the line segment SO and the line segment OF of the waveform v, the determination unit 15 determines that the attachment state of the sensor module 20 is good when the ratio of the shorter line segment to the longer line segment among the line segment SO and the line segment OF is 0.4 to 1.0. (b) When the calculation unit 14 calculates the absolute difference value |P1 - B| and the absolute difference value |B - P2| of the waveform v, the determination unit 15 determines that the attachment state of the sensor module 20 is good when the ratio |P1 - B| / |B - P2| of the absolute difference value |P1 - B| to the absolute difference value |B - P2| is 0.2 to 5.0. (c) When the calculation unit 14 calculates the area A1 and the area A2 of the waveform v, the determination unit 15 determines that the attachment state of the sensor module 20 is good when the ratio of the smaller area to the larger area among the area A1 and the area A2 is 0.4 to 1.0.

[0046] When detecting the wear of the tire T, the determination unit 15 compares the index value of the voltage change calculated by the calculation unit 14 with the reference information, and determines the progress state of the wear of the tread portion 1. At this time, the determination unit 15 reads the index value of the voltage change from the storage area 13 and executes the determination. The reference information for comparison with the index value of the voltage change is a criterion for determining that the tread portion 1 is worn. As the reference information, a ratio to the index value of the voltage change at the time of new product may be used, or a preset threshold value may be used. In a specific example, an arbitrary change rate [%] with respect to the index value of the voltage change at the time of new product can be set, or a threshold value verified in advance for a specific index value of the voltage change can be set. Note that the determination result by the determination unit 15 can be displayed, for example, on a display provided in the vehicle.

[0047] Further, when the tire information detection device 10 has the speed detection unit 16, when detecting the wear of the tire T, the determination unit 15 compares the index value of the voltage change calculated by the calculation unit 14 with the reference information corresponding to a predetermined speed range, and determines the progress state of the wear of the tread portion 1.

[0048] FIG. 4 shows the procedure of the detection method using the tire information detection device according to the embodiment of the present invention. When detecting the attachment state of the sensor module 20 attached to the tire T and the progress state of the wear in the tread portion 1 of the tire T, in step S1, the voltage detection unit 12 of the tire information detection device 10 detects the voltage generated based on the deformation of the tread portion 1 during the rotation of the tire T. At this time, the storage area 13 stores the waveform data of the voltage detected by the voltage detection unit 12 over time.

[0049] Furthermore, in step S1, the speed detection unit 16 detects the vehicle speed or the tire rotation speed, and the storage area 13 stores the waveform data of the voltage detected by the voltage detection unit 12 together with the vehicle speed or the tire rotation speed detected by the speed detection unit 16. Also, the air pressure detection unit 17 and the temperature detection unit 18 respectively detect the air pressure and the temperature, and the storage area 13 stores the waveform data of the voltage detected by the voltage detection unit 12 together with the air pressure and the temperature detected by the air pressure detection unit 17 and the temperature detection unit 18.

[0050] Next, proceed to step S2. The calculation unit 14 of the tire information detection device 10 calculates the symmetry of the waveform data, which is an index value of the mounting state of the sensor module 20, from the waveform data stored in the storage area 13. For example, in the extracted waveform v, the calculation unit 14 calculates the line segments SO and OF from the intersection point O, the start point S, and the end point F of the waveform v, and calculates the ratio of the shorter line segment to the longer line segment among the line segments SO and OF. Then, the calculation unit 14 stores the ratio of the shorter line segment to the longer line segment after the calculation in the storage area 13.

[0051] Next, proceed to step S3. The determination unit 15 of the tire information detection device 10 determines the mounting state of the sensor module 20 based on the symmetry of the waveform data calculated by the calculation unit 14. For example, when the calculation unit 14 calculates the line segments SO and OF for the waveform v, the determination unit 15 draws the conclusion that the mounting state of the sensor module 20 is good when the ratio of the shorter line segment to the longer line segment among the line segments SO and OF is in the range of 0.4 to 1.0. If the mounting state is good, proceed to step S4; if the mounting state is not good, return to step S1.

[0052] Next, proceed to step S4. The arithmetic unit 14 of the tire information detection device 10 corrects the waveform data of the voltage based on the air pressure and temperature detected by the air pressure detection unit 17 and the temperature detection unit 18. At this time, as a correction operation of the arithmetic unit 14, for example, when the air pressure detected by the air pressure detection unit 17 is relatively low, the change amount of the entire tire tends to increase, and as a result, the waveform data also tends to increase as a whole. Therefore, the arithmetic unit 14 corrects the waveform data of the voltage to decrease it at a predetermined ratio. By correcting in this way by the arithmetic unit 14, the determination accuracy of the wear progress state in the tread portion 1 can be improved. Then, the arithmetic unit 14 stores the corrected waveform data in the storage area 13. Since the air pressure inside the tire varies according to the temperature inside the tire, the temperature detected by the temperature detection unit 18 is used for the correction of the air pressure.

[0053] Next, proceed to step S5. The arithmetic unit 14 of the tire information detection device 10 calculates an index value of the voltage change from the waveform data in a predetermined speed range stored in the storage area 13. At this time, the arithmetic unit 14 may calculate the peak amplitude value between the maximum value and the minimum value in the waveform data as the index value of the voltage change (see Fig. 5(a)), or may calculate the area of the waveform data (see Fig. 5(b)). More specifically, as shown in Fig. 5(a), the arithmetic unit 14 calculates the peak amplitude value D1 [V] of the waveform data d1, or calculates the area of the waveform data d1 (the area of the hatched portion in the figure) as shown in Fig. 5(b). Then, the arithmetic unit 14 stores the calculated index value of the voltage change in the storage area 13. Note that the peak amplitude value D1 calculated by the arithmetic unit 14 indicates the value when the tire T is new.

[0054] Next, proceed to step S6. The determination unit 15 of the tire information detection device 10 determines the progress state of the wear of the tread portion 1 by comparing the index value of the voltage change calculated by the calculation unit 14 with the reference information. For example, when the index value of the voltage change is the peak amplitude value, the reference information for comparison is the change rate with respect to the peak amplitude value at the time of new product, and the change rate is set to 150%, the determination unit 15 compares the change rate based on the peak amplitude value calculated by the calculation unit 14 with the preset change rate (150%) to determine the magnitude relationship, and when the preset change rate is exceeded, a conclusion that the determination criterion is satisfied is derived. When the determination criterion is satisfied in this way, the determination operation is terminated. On the other hand, when the determination criterion is not satisfied, return to step S1.

[0055] In addition, although FIG. 4 shows an example in which the progress state of wear is determined after determining the mounting state of the sensor module 20, the present invention is not limited to this, and the determination of the mounting state of the sensor module 20 and the determination of the progress state of wear are performed in parallel, or when the mounting state of the sensor module 20 is determined to be normal, the steps (S1 to S3) for determining the mounting state at an arbitrary period are omitted, etc., and the flow of the determination operation can be appropriately changed.

[0056] In the above-described tire information detection device 10, since it includes at least one sensor module 20 disposed on the inner surface of the tire and a determination unit 15 that determines the mounting state of the sensor module 20 based on the measurement value supplied from the sensor module 20, the measurement value supplied from the sensor module 20 is used to determine the mounting state of the sensor module 20, and further, the progress state of the wear of the tread portion 1 can be accurately detected in a state where the sensor module 20 is functioning normally. In addition, by using the measurement value supplied from the sensor module 20, it is not necessary to additionally provide a dedicated device for determining the mounting state of the sensor module 20, so an increase in cost can be avoided. Note that a dedicated device for determining the mounting state of the sensor module 20 may be additionally provided in the tire information detection device 10.

[0057] In the tire information detection device, when detecting the wear of the tire T, the arithmetic unit 14 calculates line segments SO and OF from the intersection O, the start point S of the waveform v, and the end point F of the waveform v. The determination unit 15 preferably determines that the mounting state of the sensor module 20 is good when the ratio of the shorter line segment to the longer line segment among the line segments SO and OF is 0.4 to 1.0. Thereby, the determination accuracy of the mounting state of the sensor module 20 can be improved. Here, the line segments SO and OF do not have to be equal, and it is sufficient that the ratio of the shorter line segment to the longer line segment is 0.4 to 1.0. When the ratio of the shorter line segment to the longer line segment is within the above range, the sensor module 20 is normally mounted in the tire. When it is less than 0.4, the sensor module 20 is not normally mounted and accurate detection cannot be performed.

[0058] Also, when detecting the wear of the tire T, the arithmetic unit 14 calculates the absolute difference value |P1 - B| between the value P1 of the first peak point p1 and the value B of the baseline BL of the waveform data, and the absolute difference value |B - P2| between the value B of the baseline BL of the waveform data and the value P2 of the second peak point p2. The determination unit 15 may determine that the mounting state of the sensor module 20 is good when the ratio |P1 - B| / |B - P2| of the absolute difference value |P1 - B| to the absolute difference value |B - P2| is 0.2 to 5.0. At that time, the arithmetic unit 14 calculates the above ratio based on the waveform data of 10 or more rotations of the tire T, and preferably the average value thereof is 0.5 to 2.0. Thereby, the determination accuracy of the mounting state of the sensor module 20 can be improved. Here, when the ratio |P1 - B| / |B - P2| is less than 0.2, detection failure occurs at the front end of the tire in contact with the ground. Conversely, when it exceeds 5.0, detection failure occurs at the rear end of the tire in contact with the ground, or the absolute difference value |P1 - B| may be maximized due to damage to the base of the sensor module 20 or the like.

[0059] Furthermore, when detecting the wear of the tire T, the calculation unit 14 calculates the intersection point O and the areas A1 and A2 of the waveforms v1 and v2 on both sides of the waveform center axis M, and the determination unit 15 determines that the attachment state of the sensor module 20 is good when the ratio of the smaller area to the larger area among the area A1 and the area A2 is 0.4 to 1.0. Thereby, the determination accuracy of the attachment state of the sensor module 20 can be improved. Here, the areas A1 of the waveform v1 and A2 of the waveform v2 do not have to be equal, and it is sufficient if the ratio of the smaller area to the larger area is 0.4 to 1.0. When the ratio of the smaller area to the larger area is within the above range, the sensor module 20 is normally attached inside the tire. When it is less than 0.4, the sensor module 20 is not normally attached and accurate detection cannot be performed.

[0060] In the above description, in the tire information detection device 10, the index value of the voltage change is calculated using the waveform data for one rotation of the tire T, and the wear of the tire T is determined by comparing the calculated index value with the reference information. However, the waveform data for a plurality of rotations of the tire T can also be used. FIG. 6 shows the waveform data for a predetermined time stored in the storage area 13. That is, the waveform data for a predetermined time includes the waveform data for a plurality of rotations of the tire T. The dotted line in FIG. 6 indicates a predetermined threshold value, and it can be seen that there are a plurality of locations exceeding the predetermined threshold value in the waveform data for a predetermined time. The case of using the waveform data for a plurality of rotations of such a tire T will be described.

[0061] In the tire information detection device 10, when detecting the wear of the tire T, the calculation unit 14 calculates the excess frequency with respect to a predetermined threshold value from the waveform data within a predetermined speed range and a predetermined time stored in the storage area 13. Further, the calculation unit 14 can store the waveform data after the calculation in the storage area 13, and further read out the stored waveform data to execute the calculation.

[0062] Here, the predetermined speed range is a speed range with a lower limit of -5 km / h and an upper limit of +5 km / h starting from an arbitrary speed [km / h]. The arbitrary speed can be set, for example, within the range of 30 km / h to 60 km / h. Also, the predetermined time can be set, for example, within the range of 0.1 [seconds] to 10.0 [seconds]. Furthermore, as the predetermined threshold value, it can be set to a voltage [V] that can determine that the tread portion 1 is worn based on the above-mentioned predetermined speed range and predetermined time. The predetermined threshold value can set both or only one of the upper limit range and the lower limit range. Furthermore, it can be appropriately determined based on, for example, the tire size.

[0063] Also, when detecting the wear of the tire T, if the tire information detection device 10 has the air pressure detection unit 17 and the temperature detection unit 18, the calculation unit 14 can correct the waveform data or the predetermined threshold value based on the air pressure detected by the air pressure detection unit 17 and the temperature detected by the temperature detection unit 18. At this time, the calculation unit 14 reads out the waveform data or the predetermined threshold value in the predetermined speed range and predetermined time stored in the storage area 13 to execute the correction, and stores the corrected waveform data or predetermined threshold value in the storage area 13.

[0064] When detecting the wear of the tire T, the determination unit 15 determines the progress state of the wear of the tread portion 1 based on the excess frequency with respect to the predetermined threshold value calculated by the calculation unit 14. At this time, the determination unit 15 reads out the waveform data in the predetermined speed range and predetermined time from the storage area 13 to execute the determination.

[0065] Also, in steps S1 to S3 of FIG. 4, the tire information detection device 10 functions in the same manner. However, in step S4 of FIG. 4, the arithmetic unit 14 of the tire information detection device 10 may correct the waveform data of the voltage or a predetermined threshold value based on the air pressure and temperature detected by the air pressure detection unit 17 and the temperature detection unit 18. At this time, as the correction operation of the arithmetic unit 14, for example, when the air pressure detected by the air pressure detection unit 17 is relatively low, the change amount of the entire tire tends to increase, and as a result, the waveform data also tends to increase overall. Therefore, the arithmetic unit 14 corrects the waveform data of the voltage so as to decrease it at a predetermined ratio. By correcting in this way by the arithmetic unit 14, the determination accuracy of the wear progress state in the tread portion 1 can be improved. Then, the arithmetic unit 14 stores the corrected waveform data or a predetermined threshold value in the storage area 13. Since the air pressure inside the tire varies according to the temperature inside the tire, the temperature detected by the temperature detection unit 18 is used for the correction of the air pressure.

[0066] In step S5 of FIG. 4, the arithmetic unit 14 of the tire information detection device 10 may calculate the excess frequency with respect to a predetermined threshold value from the waveform data within a predetermined speed range and a predetermined time stored in the storage area 13. At this time, the arithmetic unit 14 masks the waveform data based on a predetermined threshold value and calculates the excess frequency. Specifically, a masking process of extracting the portion exceeding the predetermined threshold value is performed, and the excess frequency can be calculated by counting the number of portions exceeding the predetermined threshold value based on the waveform data after the masking process (see FIG. 7). Then, the arithmetic unit 14 stores the waveform data after the calculation in the storage area 13.

[0067] In step S6 of FIG. 4, the determination unit 15 of the tire information detection device 10 may determine the progress state of wear of the tread portion 1 based on the excess frequency with respect to a predetermined threshold value calculated by the calculation unit 14. For example, when the determination criterion for the excess frequency is preset to 15 times, the determination unit 15 concludes that the determination criterion is not satisfied if the excess frequency in the waveform data at a certain point in time is 10 times, and the determination criterion is satisfied if the excess frequency in the waveform data at another point in time is 15 times. The determination criterion can be set, for example, as the number of times of exceeding a predetermined threshold value or as a ratio to the number of times of exceeding when new. When the determination criterion is satisfied in this way, the determination operation is terminated. On the other hand, when the determination criterion is not satisfied, the process returns to step S1. Alternatively, if it has already been determined that the mounting state of the sensor module 20 is normal, the steps (S1 to S3) for determining the mounting state in an arbitrary period (for example, it can be set from 1 minute to 1 week) can also be omitted. As described above, when the tire information detection device 10 uses the waveform data for a plurality of rotations of the tire T, it functions differently from the case where the waveform data for one rotation of the tire T is used, but in any case, it can accurately detect the progress state of wear in the tread portion 1.

[0068] FIG. 8 shows a modified example of the procedure of the detection method using the tire information detection device according to the embodiment of the present invention. In FIG. 8, the determination unit 15 of the tire information detection device 10 executes at least two determination operations, and finally determines the progress state of the wear of the tread portion 1 based on the results of these determination operations. The procedure shown in FIG. 8 is the same as the procedure shown in FIG. 4 up to step S6. Next, proceeding to step S7 after step S6, the voltage detection unit 12 detects the voltage generated by the element 11, and the speed detection unit 16 detects the vehicle speed or the tire rotation speed. Next, proceeding to step S8, the calculation unit 14 corrects the waveform data or a predetermined threshold value based on the air pressure and temperature detected by the air pressure detection unit 17 and the temperature detection unit 18. Then, the calculation unit 14 stores the corrected waveform data or a predetermined threshold value in the storage area 13. Next, proceeding to step S9, the calculation unit 14 calculates an index value of the voltage change or the excess frequency with respect to a predetermined threshold value from the waveform data within a predetermined speed range or a predetermined speed range and a predetermined time stored in the storage area 13. Then, the calculation unit 14 stores the calculated index value of the voltage change or the waveform data in the storage area 13. Next, proceeding to step S10, the determination unit 15 executes the second determination operation. At that time, if any determination criterion is satisfied, the determination operation is terminated. On the other hand, if the determination criterion is not satisfied, the process returns to step S7. Here, when the determination unit 15 executes the second determination operation, the first determination operation (steps S4 to S6) and the second determination operation (steps S7 to S10) may be executed on the same day, or the first determination operation and the second determination operation may be executed on different days.

[0069] As described above, by the determination unit 15 executing at least two determination operations, it is possible to suppress the occurrence of sudden errors in the final determination result and improve the determination accuracy of the progress state of the wear in the tread portion 1.

[0070] In the embodiment of FIG. 8, an example in which the number of determinations by the determination unit 15 is set to two is shown, but it is not particularly limited, and it can be set to any number as long as it is plural. Further, in the embodiment of FIG. 8, an example in which the process returns to step S7 when the determination criteria are not satisfied in step S10 is shown, but the configuration may be such that the process returns to step S1 when the determination criteria are not satisfied in step S10.

[0071] FIG. 9 shows an inflated tire (tire T) determined by the tire information detection device 10 according to an embodiment of the present invention. FIGS. 10 to 12 show the sensor module 20 or the container 30 attached to the tire T. In FIGS. 10 and 12, the arrow Tc indicates the tire circumferential direction, and the arrow Tw indicates the tire width direction.

[0072] As shown in FIG. 9, the tire T includes a tread portion 1 that extends in the tire circumferential direction and forms an annular shape, a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3, 3 disposed on the inner side in the tire radial direction of these sidewall portions 2.

[0073] A carcass layer 4 is mounted between the pair of bead portions 3, 3. This carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inner side to the outer side around the bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is disposed on the outer circumference of the bead core 5. An inner liner layer 9 is disposed in the region between the pair of bead portions 3, 3 on the inner surface Ts of the tire. This inner liner layer 9 forms the inner surface Ts of the tire.

[0074] On one side, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged such that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in the range of, for example, 10° to 40°. As the reinforcing cord of the belt layer 7, a steel cord is preferably used. On the outer peripheral side of the belt layer 7, at least one belt cover layer 8 is arranged for the purpose of improving high-speed durability, in which the reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

[0075] Note that the above-described tire internal structure shows a typical example in a pneumatic tire, but is not limited thereto.

[0076] In the region corresponding to the tread portion 1 of the tire inner surface Ts of the tire T, at least one rubber container 30 is fixed. A sensor module 20 is inserted into the container 30. The container 30 has an opening 31 into which the sensor module 20 is inserted, and is joined to the tire inner surface Ts via an adhesive layer 32. Since the sensor module 20 is configured to be accommodated in the container 30 in a freely removable manner, it can be appropriately replaced when the replacement time of the sensor module 20 or when a failure occurs, etc. Further, since the container 30 is made of rubber, it is suitable because it expands and contracts when the sensor module 20 is inserted into and removed from the opening 31.

[0077] Examples of materials for the container 30 include chloroprene rubber (CR), butyl rubber (IIR), natural rubber (NR), acrylonitrile-butadiene copolymer rubber (NBR), butadiene rubber (BR), styrene-butadiene rubber (SBR), etc., and a blend body using a single one or a mixture of two or more thereof can be used. Since these materials are excellent in adhesion to the butyl rubber constituting the inner surface Ts of the tire, when the container 30 is made of the above materials, sufficient adhesion between the container 30 and the inner surface Ts of the tire can be ensured.

[0078] As shown in FIG. 12, the sensor module 20 includes a housing 21 and electronic components 22. The housing 21 has a hollow structure and houses the electronic components 22 therein. The electronic components 22 can be appropriately configured to include a sensor 23 for acquiring tire information such as the voltage, speed, air pressure, temperature, etc. described above in the tire T, a transmitter, a receiver, a control circuit, a battery, and the like. As the sensor 23, for example, a speed sensor (speed detection unit 16), a pressure sensor (air pressure detection unit 17), or a temperature sensor (temperature detection unit 18) can be used together with a piezoelectric sensor (element 11 and voltage detection unit 12). In particular, the piezoelectric sensor includes an element 11 that generates a voltage based on the deformation of the tread portion 1 during tire rotation. This piezoelectric sensor is different from a piezoelectric acceleration sensor. In addition to the various sensors described above, an acceleration sensor or a magnetic sensor can also be used. Further, the sensor module 20 is configured to be able to transmit the tire information acquired by the sensor 23 to the storage area 13. Furthermore, in order to facilitate gripping of the sensor module 20, a knob portion 24 protruding from the housing 21 may be provided, and the knob portion 24 can carry the function of an antenna. Note that the internal structure of the sensor module 20 shown in FIG. 12 is an example of the sensor module and is not limited thereto.

[0079] The container 30 is joined to the inner surface Ts of the tire via an adhesive layer 32. The container 30 has a plate-like base 33 joined to the inner surface Ts of the tire, a cylindrical tube portion 34 protruding from the base 33, and a housing portion 35 formed within the tube portion 34. This housing portion 35 communicates with a circular opening 31. Thus, the housing portion 35 has a substantially rectangular cross-sectional shape with the base 33 as the bottom surface and the opening 31 as the top surface. A cylindrical sensor module 20 with a tapered upper surface is housed in the housing portion 35. Note that the shapes of the base 33, the tube portion 34, and the housing portion 35 are not particularly limited and can be appropriately changed according to the shape of the sensor module 20 inserted into the container 30.

[0080] The adhesive layer 32 is not particularly limited as long as it can adhere a rubber composition. For example, as the adhesive layer 32, a cyanoacrylate-based adhesive (instant adhesive) or a polyurethane-based adhesive may be used. In the case of a cyanoacrylate-based adhesive, the working time for installing the container 30 on the inner surface Ts of the tire can be shortened, and in the case of a polyurethane-based adhesive, it is suitable because it has excellent adhesiveness to vulcanized rubber. Also, as the adhesive layer 32, an adhesive tape, a vulcanizing adhesive that cures naturally (can be vulcanized at room temperature), or a puncture repair agent used as an emergency measure when a pneumatic tire is punctured may be used. When a vulcanizing adhesive is used as the adhesive layer 32, it is not necessary to perform a primer treatment required to fix the container using an adhesive tape or the like, and productivity can be improved. Note that the primer treatment (undercoating treatment) is performed in advance to improve the adhesiveness to the inner surface of the tire.

[0081] In the pneumatic tire described above, at least one rubber container 30 for inserting the sensor module 20 is provided on the inner surface Ts of the tire. The container 30 has a plate-shaped base 33 joined to the inner surface Ts of the tire via an adhesive layer 32, a cylindrical portion 34 protruding from the base 33, a housing portion 35 formed within the cylindrical portion 34, and an opening 31 communicating with the housing portion 35. Therefore, the operation of inserting the sensor module 20 into the container 30 is easy, and the sensor module 20 can be securely held by tightening the container 30, preventing the sensor module 20 from falling off.

[0082] In the above pneumatic tire, the container 30 is joined to the inner surface Ts of the tire via the adhesive layer 32. As the roughness of the inner surface Ts of the tire, it is preferable that the arithmetic mean height Sa is in the range of 0.3 μm to 15.0 μm and the maximum height Sz is in the range of 2.5 μm to 60.0 μm. By appropriately setting the arithmetic mean height Sa and the maximum height Sz as the roughness of the inner surface Ts of the tire in this way, the adhesive area between the inner surface Ts of the tire and the adhesive layer 32 can be increased, and the adhesiveness between the inner surface Ts of the tire and the container 30 can be effectively improved. When the arithmetic mean height Sa exceeds 15.0 μm and the maximum height Sz exceeds 60.0 μm, the adhesive layer 32 cannot follow the unevenness of the inner surface Ts of the tire, and the adhesiveness tends to decrease. The arithmetic mean height Sa and the maximum height Sz are values measured in accordance with ISO25178 and can be measured using a commercially available surface property measuring instrument (for example, a shape analysis laser microscope or a 3D shape measuring instrument). The measuring method may be either a contact type or a non-contact type.

[0083] In FIGS. 9 and 11, the container 30 is disposed inside the tire width direction from the ground contact end. Also, the container 30 may be unevenly distributed on one side in the tire width direction with respect to the tire center line CL. The sensor 23 in the sensor module 20 inserted into the container 30 can accurately acquire tire information.

[0084] In the above-described pneumatic tire, the container 30 is preferably set to the following dimensions. It is preferable that the width Lc1 of the opening 31 of the container 30 and the inner width Lc2 of the bottom surface of the container 30 satisfy the relationship Lc1 < Lc2. By making the width Lc1 of the opening 31 narrower than the inner width Lc2 of the bottom surface of the container 30 in this way, the restraining force on the upper surface side of the container 30 can be strengthened, and the sensor module 20 inserted into the container 30 can be effectively prevented from falling off. Thereby, it is possible to achieve both workability during insertion of the sensor module 20 and the holding property of the container 30. Note that the width Lc1 of the opening 31 and the inner width Lc2 of the bottom surface in the container 30 are both measured in a state where the sensor module 20 is not inserted into the container 30.

[0085] Also, the average thickness of the container 30 is preferably 0.5 mm to 5.0 mm. By appropriately setting the average thickness of the container 30 in this way, it is possible to improve the workability during insertion of the sensor module 20, the holding property of the container 30, and the fracture resistance of the container 30 in a well-balanced manner. Here, if the average thickness of the container 30 is less than 0.5 mm, the container 30 is likely to break when the sensor module 20 is inserted. If the average thickness of the container 30 is greater than 5.0 mm, the rigidity of the container 30 becomes excessively large, and the sensor module 20 cannot be easily inserted. Note that the average thickness of the container 30 is measured from the thickness of the rubber constituting the container 30.

[0086] In particular, it is desirable that the container 30 and the sensor module 20 satisfy the following dimensional relationships. It is preferable that the width Lc1 of the opening 31 of the container 30 and the maximum width Lsm of the sensor module 20 inserted into the container 30 satisfy the relationship of 0.10 ≦ Lc1 / Lsm ≦ 0.95, more preferably satisfy the relationship of 0.15 ≦ Lc1 / Lsm ≦ 0.80, and most preferably satisfy the relationship of 0.15 ≦ Lc1 / Lsm ≦ 0.65. By appropriately setting the ratio of the width Lc1 of the opening 31 of the container 30 to the maximum width Lsm of the sensor module 20 in this way, it is possible to effectively prevent the sensor module 20 from falling off, and improve the workability when inserting the sensor module 20 and the holding property of the container 30. In the sensor module 20 of FIG. 12, the maximum width Lsm corresponds to the width Ls2 of the lower surface.

[0087] Also, it is preferable that the width Lc1 of the opening 31 of the container 30, the inner width Lc2 of the bottom surface of the container 30, the width Ls1 of the upper surface of the sensor module 20, and the width Ls2 of the lower surface of the sensor module 20 satisfy the relationship of Lc1 < Ls1 ≦ Ls2 ≦ Lc2. Furthermore, it is more preferable that the upper surface of the sensor module 20 is formed in a tapered shape and satisfies the relationship of Ls1 < Ls2. By appropriately setting the respective widths of the container 30 and the sensor module 20 in this way, it is possible to effectively prevent the sensor module 20 from falling off. Also, in the sensor module 20, a form in which the diameter gradually decreases from the upper surface to the lower surface can be adopted. In this case, it is preferable to satisfy the relationships of Ls2 < Ls1 and Ls2 ≦ Lc2 and Lc1 < Ls1.

[0088] Furthermore, the ratio of the height Hc of the container 30 in the state where the sensor module 20 is inserted to the height Hs (maximum height) of the sensor module 20 is preferably in the range of 0.5 to 1.5, more preferably in the range of 0.6 to 1.3, and most preferably in the range of 0.7 to 1.0. By appropriately setting the ratio of the height Hc of the container 30 to the height Hs of the sensor module 20 in this way, the dropout of the sensor module 20 can be effectively prevented. Note that the height Hs of the sensor module 20 is the height including the knob portion 24 when the knob portion 24 is provided on the sensor module 20 (see FIG. 12). Also, the height Hc of the container 30 is the height of the cylindrical portion 34 without including the height of the base portion 33 (see FIG. 12).

[0089] In the pneumatic tire described above, it is preferable that the rubber constituting the container 30 has the following physical properties. The elongation at break EB is 50% to 900%, and the modulus at 300% elongation (M300) is preferably 2 MPa to 15 MPa. By appropriately setting the elongation at break EB and the modulus (M300) in this way, the workability at the time of inserting the sensor module 20, the retention of the container 30, and the fracture resistance of the container 30 can be improved in a well-balanced manner.

Example

[0090] A tire of size 275 / 40R21, comprising at least one sensor module disposed on the inner surface of the tire, an element mounted on the sensor module for generating a voltage based on the deformation of the tread portion during tire rotation, a voltage detection unit for detecting the voltage generated by the element, a storage area for storing waveform data of the voltage detected by the voltage detection unit over time, an arithmetic unit for calculating the symmetry of the waveform data, which serves as an index value for the mounting state of the sensor module, from the waveform data stored in the storage area, and for calculating an index value of voltage change from the waveform data stored in the storage area, a determination unit for determining the mounting state of the sensor module based on the symmetry of the waveform data calculated by the arithmetic unit, and for determining the progress of tread wear by comparing the index value of voltage change calculated by the arithmetic unit with reference information. The sensor module is fixed to the inner surface of the tire via a container in which the sensor module is housed. The container has an opening into which the sensor module is inserted. Tires of Examples 1 to 6 were manufactured in which the ratio (Lc1 / Lsm) of the width Lc1 of the opening to the maximum width Lsm of the sensor module was set as shown in Table 1.

[0091] For these test tires, the mounting state detection performance, wear detection performance, workability during insertion of the sensor module, and durability were evaluated by the following test methods, and the results are shown together in Table 1.

[0092] Mounting state detection performance: For each test tire, the mounting state of the sensor module was determined by a tire information detection device. For example, in the tire of Example 1, waveform data as shown in FIG. 2 was obtained. As shown in the figure, when the mounting state of the sensor module was good, it was confirmed that the waveform data had symmetry. That is, the waveform data was useful as an index value for the mounting state of the sensor module, and a correlation was recognized between the voltage and the mounting state of the sensor module. When there was also a correlation between the voltage and the mounting state of the sensor module for Examples 2 to 6, it was shown as "good" in Table 1.

[0093] Wear detection performance: For each test tire, the progress of wear in the tread portion was determined by the tire information detection device. For example, in the tire of Example 1, waveform data as shown in FIG. 13 was obtained. As shown in the figure, as the wear of the tread portion progresses from new tire state A to the late wear stage D (the ratio of the groove depth at each time point to the groove depth at the time of new tire becomes lower), it was confirmed that the peak amplitude value of the waveform data at each time point gradually increases. That is, the peak amplitude value of the waveform data is useful as an index value of voltage change, and a correlation was recognized between voltage and groove depth. When there was also a correlation between voltage and groove depth for Examples 2 to 6, it was shown as "good" in Table 1.

[0094] Workability during insertion of the sensor module: For each test tire, the required time for the operation of inserting the sensor module into the container provided on the inner surface of the tire was measured. The evaluation results were shown by an index with the reciprocal of the measured value and taking Example 1 as 100. The larger this index value is, the easier the insertion operation of the sensor module is.

[0095] Durability: Each test tire was assembled to a wheel with a rim size of 21×9.5J, and after conducting a running test on a drum tester under the conditions of an air pressure of 120 kPa, 102% of the maximum load, a running speed of 81 km, and a running distance of 10,000 km, the occurrence of damage to the container or dropout of the sensor module was visually confirmed. The evaluation results showed the presence or absence of damage to the container and the presence or absence of dropout of the sensor module.

[0096]

Table 1

[0097] As can be seen from this Table 1, the tire information detection devices of Examples 1 to 6 all had good attachment state detection performance and wear detection performance. For the pneumatic tires of Examples 2 to 6, the workability during insertion of the sensor module was improved compared to Example 1. For the pneumatic tires of Examples 3 to 5, there was no damage to the container and no dropout of the sensor module.

Description of Symbols

[0098] 1 Tread portion 2 Sidewall portion 3 Bead portion 10 Tire information detection device 11 Element 12 Voltage detection section 13 Memory area 14 Arithmetic section 15 Judgment section 16 Speed detection section 17 Air pressure detection section 18 Temperature detection section 20 Sensor module 30 Container Ts Inner surface of tire CL Tire center line

Claims

1. In a tire information detection device that detects tire information including at least one of tire wear, tire deformation, road surface condition, tire contact condition, presence or absence of tire failure, tire driving history, and tire load condition, at least one sensor module disposed on the inner surface of the tire, an element mounted on the sensor module that generates a voltage based on deformation of the tread portion during tire rotation, a voltage detection unit that detects the voltage generated by the element, a storage area that stores waveform data over time of the voltage detected by the voltage detection unit, an arithmetic unit that calculates the symmetry of the waveform data, which is an index value of the mounting state of the sensor module, from the waveform data stored in the storage area, and a determination unit that determines the mounting state of the sensor module based on a measurement value supplied from the sensor module, wherein the determination unit determines the mounting state of the sensor module based on the symmetry of the waveform data calculated by the arithmetic unit.

2. The arithmetic unit extracts a waveform including a first peak point and a second peak point formed on both sides of the baseline of the waveform data, calculates line segments SO and OF from an intersection point O where a line connecting the first peak point and the second peak point intersects the baseline of the waveform data, a start point S of the waveform, and an end point F of the waveform. The tire information detection device according to claim 1, wherein the determination unit determines that the mounting state of the sensor module is good when a ratio of the shorter line segment to the longer line segment among the line segment SO and the line segment OF is 0.4 to 1.

0.

3. The arithmetic unit extracts a waveform including a first peak point and a second peak point formed on both sides of the baseline of the waveform data, and calculates an absolute difference value |P1 - B| between a value P1 of the first peak point and a value B of the baseline of the waveform data and an absolute difference value |B - P2| between the value B of the baseline of the waveform data and a value P2 of the second peak point. The tire information detection device according to claim 1, wherein the determination unit determines that the mounting state of the sensor module is good when a ratio |P1 - B| / |B - P2| of the absolute difference value |P1 - B| to the absolute difference value |B - P2| is 0.2 to 5.

0.

4. The calculation unit extracts a waveform including a first peak point and a second peak point formed on both sides of the baseline of the waveform data, calculates an intersection point O where a line connecting the first peak point and the second peak point intersects the baseline of the waveform data, and calculates areas A1 and A2 of the waveform on both sides of a waveform center axis passing through the intersection point O and perpendicular to the baseline of the waveform data. The tire information detection device according to claim 1, wherein the determination unit determines that the mounting state of the sensor module is good when a ratio of the smaller area to the larger area among the area A1 and the area A2 is 0.4 to 1.

0.

5. The calculation unit calculates an index value of voltage change from the waveform data stored in the storage area, and the determination unit determines a progress state of wear of the tread portion by comparing the index value of voltage change calculated by the calculation unit with reference information. The tire information detection device according to any one of claims 1 to 4.

6. The tire information detection device according to any one of claims 1 to 5, further comprising a speed detection unit that detects a vehicle speed or a tire rotation speed, wherein the storage area stores waveform data of voltage over time detected by the voltage detection unit together with the vehicle speed or the tire rotation speed detected by the speed detection unit, the calculation unit calculates an index value of voltage change from the waveform data in a predetermined speed range stored in the storage area, and the determination unit determines a progress state of wear of the tread portion by comparing the index value of voltage change calculated by the calculation unit with reference information corresponding to the predetermined speed range.

7. The tire information detection device according to claim 5 or 6, wherein the calculation unit calculates a peak amplitude value between a maximum value P1 and a minimum value P2 in the waveform data as the index value of voltage change.

8. It has a speed detection unit that detects the vehicle speed or the tire rotation speed, the storage area stores the waveform data over time of the voltage detected by the voltage detection unit together with the vehicle speed or the tire rotation speed detected by the speed detection unit, the calculation unit calculates the excess frequency with respect to a predetermined threshold value from the waveform data within a predetermined speed range and a predetermined time stored in the storage area, and the determination unit determines the progress state of the wear of the tread portion based on the excess frequency with respect to the predetermined threshold value calculated by the calculation unit. The tire information detection device according to any one of claims 1 to 4, characterized in that.

9. It has an air pressure detection unit that detects the air pressure inside the tire, and the calculation unit corrects the waveform data or the predetermined threshold value based on the air pressure detected by the air pressure detection unit. The tire information detection device according to any one of claims 5 to 8, characterized in that.

10. The determination unit executes at least two determination operations, and finally determines the progress state of the wear of the tread portion based on the results of these determination operations. The tire information detection device according to any one of claims 5 to 9, characterized in that.

11. The sensor module includes at least the element and the voltage detection unit, and the sensor module is fixed to the inner surface of the tire via a container into which the sensor module is inserted. The tire information detection device according to any one of claims 5 to 10, characterized in that.

12. The container is joined to the inner surface of the tire via an adhesive layer, and as the roughness of the inner surface of the tire, the arithmetic mean height Sa is in the range of 0.3 μm to 15.0 μm, and the maximum height Sz is in the range of 2.5 μm to 60.0 μm. The tire information detection device according to claim 11, characterized in that.

13. The width Lc1 of the opening of the container and the inner width Lc2 of the bottom surface of the container satisfy the relationship Lc1 < Lc2. The tire information detection device according to claim 11 or 12, characterized in that.

14. The width Lc1 of the opening of the container and the maximum width Lsm of the sensor module satisfy the relationship 0.10 ≦ Lc1 / Lsm ≦ 0.

95. The tire information detection device according to any one of claims 11 to 13, characterized in that.

15. The tire information detection device according to any one of claims 11 to 14, characterized in that the width Lc1 of the opening of the container, the inner width Lc2 of the bottom surface of the container, the width Ls1 of the upper surface of the sensor module, and the width Ls2 of the lower surface of the sensor module satisfy the relationship Lc1 < Ls1 ≤ Ls2 ≤ Lc2.

16. The tire information detection device according to any one of claims 11 to 15, characterized in that the average thickness of the container is 0.5 mm to 5.0 mm.

17. The tire information detection device according to any one of claims 11 to 16, characterized in that the ratio of the height Hc of the container in a state where the sensor module is inserted to the height Hs of the sensor module is in the range of 0.5 to 1.

5.

18. The tire information detection device according to any one of claims 11 to 17, characterized in that the elongation at break EB of the rubber constituting the container is 50% to 900%, and the modulus at 300% elongation of the rubber constituting the container is 2 MPa to 15 MPa.

19. The tire information detection device according to any one of claims 11 to 18, characterized in that the container is arranged inside the tire width direction from the ground end.

20. The tire information detection device according to any one of claims 1 to 18, characterized in that the element is a piezoelectric element.

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