Tire

Abstract

The invention provides a tire capable of improving sensing accuracy of a functional component and improving measurement performance of tire information. In a tire provided with a functional member (20) having a sensor function for detecting tire information on the rear surface of a tread portion (1), the functional member (20) has a contact surface (21) that comes into contact with the rear surface side of the tread portion (1), and when a first projection region (S0) formed by projecting the contact surface (21) onto a tread surface of the tread portion (1) is defined, a second projection region (S0) is formed by projecting the contact surface (21) onto the tread surface of the tread portion (1). The groove area ratio (GR0) in the first projection region (S0) in the new tire state is within the range of 50.0% < = GR0 < = 100.0%.

Description

Technical Field

[0001] The present invention relates to a tire having a functional component having a sensor function for detecting tire information, and more particularly, to a tire capable of improving the sensing accuracy of the functional component and measuring performance of tire information. Background Art

[0002] The industry has been implementing an operation of providing a functional component (e.g., a sensor unit including a sensor) on the inner surface of a tire to obtain tire information (e.g., see Patent Documents 1 to 3). In this functional component, an operation is also implemented to detect not only temperature and internal pressure but also physical quantity changes caused by deformation of the tread portion generated when the tire is running as tire information.

[0003] However, tire information such as physical quantities observed due to tread deformation is greatly affected by the structural characteristics of the portion where the functional component is installed. Therefore, depending on the installation position of the functional component, the sensing accuracy of the functional component may not be fully ensured.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-146875

[0007] Patent Document 2: Japanese Patent Application Publication No. 2021-60401

[0008] Patent Document 3: Japanese Patent Publication No. 2018-512333 Summary of the invention

[0009] Problems to be solved by the invention

[0010] An object of the present invention is to provide a tire capable of improving the sensing accuracy of a functional component and the measurement performance of tire information.

[0011] Means used to solve problems

[0012] The tire of the present invention for achieving the above-mentioned object is a tire having a functional component having a sensor function for detecting tire information on the back side of the tread portion, characterized in that:

[0013] The functional component has a contact surface that contacts the back side of the tread portion. When a first projection area S0 formed by projecting the contact surface onto the tread surface of the tread portion is specified, the groove area ratio GR0 within the first projection area S0 when the tire is in a new state is in the range of 50.0%≤GR0≤100.0%.

[0014] Effects of the Invention

[0015] The present inventors conducted intensive studies on functional components provided on the back side of the tread portion based on evaluations in actual tires and simulation evaluations and found that the positional relationship between the grooves formed in the tread portion and the functional components greatly affects the measurement results, thereby completing the present invention.

[0016] That is, in the present invention, when the functional component is provided on the back of the tread portion, by providing the functional component at a position where the overlap with the groove is as large as possible, the excessive impact received from the road surface when the tire contacts the ground is not easily transmitted to the functional component, and the physical quantity change caused by the deformation of the tread portion can be detected with high accuracy, so that the sensing accuracy of the functional component can be improved and the measurement performance of the tire information can be improved. Sensing accuracy means the ability to detect the physical quantity change caused by the deformation of the tread portion with high accuracy. By improving the sensing accuracy, the coefficient of variation CV of the peak-to-peak value of the output waveform becomes smaller, and the physical quantity change caused by the deformation of the tread portion can be accurately grasped.

[0017] In the present invention, the functional component has a sensor element for detecting tire information, and the sensor element is arranged in the contact surface. When a second projection area S formed by projecting the sensor element onto the tread surface of the tread portion is specified, the groove area ratio GR in the second projection area S of the tire in the new state is preferably within the range of 80.0%≤GR≤100.0%. In this way, by arranging the sensor element at a position where the overlap amount with the groove is as large as possible, the excessive impact received from the road surface when the tire contacts the ground is not easily transmitted to the sensor element, and the physical quantity change caused by the deformation of the tread portion can be detected with high accuracy, thereby improving the sensing accuracy of the functional component.

[0018] When a first three-dimensional area V0 is defined and formed by a trajectory when the first projection area S0 is moved from the tread position of the new tire to the contact surface by the rubber thickness of the tread portion, the groove volume ratio GRV0 in the first three-dimensional area V0 is preferably within the range of 50.0% ≤ GRV0 ≤ 100.0%. In this way, by increasing the volume of the groove in the area directly above the functional component as much as possible, the excessive impact received from the road surface when the tire contacts the ground is not easily transmitted to the functional component, and the physical quantity change caused by the deformation of the tread portion can be detected with high accuracy, thereby improving the sensing accuracy of the functional component.

[0019] When a second three-dimensional area V is defined and formed by a trajectory when the second projection area S is moved from the tread position of the new tire to the contact surface by the rubber thickness of the tread portion, the groove volume ratio GRV in the second three-dimensional area V is preferably within the range of 60.0% ≤ GRV ≤ 100.0%. In this way, by increasing the volume of the groove in the area directly above the sensor element as much as possible, the excessive impact received from the road surface when the tire contacts the ground is not easily transmitted to the sensor element, and the physical quantity change caused by the deformation of the tread portion can be detected with high accuracy, thereby improving the sensing accuracy of the functional component.

[0020] The change rate RGR0 of the groove area ratio GR0 in the first projection area S0 when the tread is 80% worn relative to the groove area ratio GR0 in the first projection area S0 when the tire is new is preferably within ±20. The groove area ratio GR0 in the first projection area S0 changes as the wear of the tread progresses, and decreases in ordinary tires. By specifying the change rate RGR0 as described above, the change in the groove area ratio GR0 in the first projection area S0 due to wear becomes smaller, so the effect of improving the sensing accuracy will continue from the new time to the worn time, so that a high sensing accuracy can be continuously obtained during the wear life of the tire.

[0021] The change rate RGR of the groove area ratio GR in the second projection area S when the tread is 80% worn relative to the groove area ratio GR in the second projection area S when the tire is new is preferably within ±10%. The groove area ratio GR in the second projection area S changes as the tread wear progresses, and decreases in ordinary tires. By specifying the change rate RGR as described above, the change in the groove area ratio GR in the second projection area S due to wear becomes smaller, so the effect of improving the sensing accuracy will continue from the new time to the worn time, so that a high sensing accuracy can be continuously obtained during the tire wear life.

[0022] In a tire having a circumferential main groove extending in the circumferential direction of the tire formed in the tread portion, when the tire is new, preferably more than 80% of the groove area included in the second projection area S comes from the circumferential main groove. By arranging the sensor element in the area just above the circumferential main groove, the sensing accuracy of the functional component can be effectively improved, and this effect can be continuously obtained.

[0023] In a tire with a belt layer buried in the tread portion, the second projection area S is preferably arranged in the extension area of ​​the belt layer. By arranging the sensor element in the extension area of ​​the belt layer, deformation of the tread portion caused by contact with the ground can be efficiently detected.

[0024] In a tire in which a circumferential main groove extending in the tire circumferential direction is formed in the tread portion and a wear indicator formed by a groove bottom protrusion is formed in the circumferential main groove, the wear indicator is preferably arranged at a position outside the range of 20 mm from the center position of the second projection area S in the tire circumferential direction. If the wear indicator exists in the circumferential main groove around the sensor element, the excessive impact received from the road surface when the tire contacts the ground is easily transmitted to the sensor element, so by keeping such a wear indicator away from the sensor element, the sensing accuracy of the functional component can be improved.

[0025] The tire of the present invention preferably has a marking capable of identifying the position of the sensor element in the tire side region, and the marking is arranged within a range of ±10° from the center position of the second projection area S in the tire circumferential direction with the tire rotation axis as the center. Thus, the position of the sensor element can be identified from the outside of the tire, thereby improving the workability of installing or maintaining the functional component.

[0026] In the present invention, it is preferred that a container for accommodating the functional components is fixed to the back of the tread portion, and the functional components are accommodated in the container. The container is preferably fixed to the back of the tread portion by an adhesive. The container is preferably made of vulcanized rubber. When such a container is used, the above-mentioned excellent effect can also be obtained.

[0027] In addition, the functional component preferably has a sensor function obtained by using a piezoelectric element as a sensor element. When such a functional component having a sensor function obtained by using a piezoelectric element is used, a significant effect can be obtained.

[0028] The tire of the present invention is preferably a pneumatic tire, but may also be a non-pneumatic tire. When it is a pneumatic tire, its interior may be filled with inert gas such as air, nitrogen or other gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention.

[0030] Figure 2 Yes means Figure 1 A top view of the tread portion of a pneumatic tire.

[0031] Figure 3 Yes means Figure 1 A top view of a portion of a pneumatic tire where functional components are disposed.

[0032] Figure 4 yes Figure 3 The IV-IV arrow cross-section diagram.

[0033] Figure 5 It is a three-dimensional diagram showing a functional component and its housing.

[0034] Figure 6 Yes means Figure 1 A three-dimensional cross-sectional view of the tread portion of a pneumatic tire.

[0035] Figure 7 Yes means Figure 1 A side view of a sidewall portion of a pneumatic tire.

[0036] Figure 8 This is a diagram showing an example of an output waveform from a piezoelectric element. DETAILED DESCRIPTION

[0037] Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings. Figure 1 to Figure 7 It is a figure which shows the pneumatic tire comprised by embodiment of this invention.

[0038] like Figure 1 As shown, the pneumatic tire of this embodiment includes a tread portion 1 extending in the tire circumferential direction and formed in an annular shape, a pair of sidewall portions 2, 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3, 3 arranged on the inner side of the sidewall portions 2 in the tire radial direction.

[0039] A carcass layer 4 is provided between a pair of bead portions 3, 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the radial direction of the tire and is folded back from the inner side to the outer side of the tire around a bead core 5 disposed at each bead portion 3. A bead core 6 made of a rubber composition and having a triangular cross section is disposed on the outer periphery of the bead core 5.

[0040] On the other hand, a plurality of belt layers 7 are buried 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 relative to the circumferential direction of the tire, and the reinforcing cords are arranged between the layers in a mutually crossed manner. In the belt layer 7, the inclination angle of the reinforcing cords relative to the circumferential direction of the tire is set, for example, in the range of 10° to 40°. As the reinforcing cords of the belt layer 7, steel cords are preferably used. In order to improve high-speed durability, at least one belt cover layer 8 is arranged on the outer peripheral side of the belt layer 7, in which the reinforcing cords are arranged at an angle of, for example, less than 5° relative to the circumferential direction of the tire. As the reinforcing cords of the belt cover layer 8, organic fiber cords such as nylon and aramid are preferably used.

[0041] It should be noted that the above tire internal structure shows a representative example of a pneumatic tire, but is not limited thereto.

[0042] like Figure 2As shown in FIG. 1 , four circumferential grooves 11 extending in the circumferential direction of the tire are formed on the tread surface of the tread portion 1. The circumferential grooves 11 include, for example, three circumferential main grooves 11A and one circumferential narrow groove 11B. The circumferential main groove 11A is a groove having a groove width in the range of 6.5 mm to 20.0 mm and a groove depth in the range of 5.0 mm to 8.5 mm and having a wear indicator. The circumferential main groove 11A and the circumferential narrow groove 11B have chamfered portions 12A and 12B, respectively, and such chamfered portions 12A and 12B constitute a part of the circumferential main groove 11A and the circumferential narrow groove 11B, respectively. Therefore, the chamfered portions 12A and 12B are included in the groove area and the groove volume.

[0043] The circumferential grooves 11 define five rows of land portions 13 on the tread portion 1. In addition, a plurality of lug grooves 14 extending in the tire width direction are formed at intervals in the tire circumferential direction in each land portion 13. Groove components such as sipes may be added to the tread portion 1 as needed.

[0044] In the above-mentioned pneumatic tire, grooves such as circumferential grooves 11 and lug grooves 14 are formed on the tread surface of the tread portion 1, and on the other hand, Figure 1 As shown, a cylindrical functional component 20 having a sensor function for detecting tire information is provided on the back surface of the tread portion 1 .

[0045] like Figure 3 to Figure 5 As shown, the functional element 20 is accommodated in the interior of the container 30. The container 30 has a flat bottom 31 fixed to the back of the tread portion 1, a cylindrical side wall portion 32 protruding from the bottom 31, a container portion 33 formed by these bottoms 31 and the side walls 32, and an opening portion 34 connected to the container portion 33. The container 30 can be a molded body made of vulcanized rubber. The container 30 thus constructed is fixed to the back of the tread portion 1 by an adhesive, for example, and the functional component 20 is accommodated in the container 30. The functional component 20 is preferably arranged on the tread surface of the tread portion 1 through the container 30, but it can also be directly attached to the back of the tread portion 1 without the container 30. In any case, the functional component 20 has a contact surface 21 that contacts the back side of the tread portion 1. That is, the contact surface 21 is a surface that contacts the back of the tread portion 1 or the surface of the bottom 31 of the container 30.

[0046] The functional component 20 has a structure for accommodating various electronic components inside the shell. The electronic components can be configured to include various sensors, transmitters, receivers, control circuits, batteries, etc. for obtaining tire information. Examples of tire information obtained by the sensor include the internal temperature, internal pressure, and wear amount of the tread portion of the pneumatic tire. For example, a temperature sensor or a pressure sensor is used to measure the internal temperature or internal pressure. When detecting the wear amount of the tread portion, for example, a sensor element 22 composed of a piezoelectric element is arranged on the contact surface 21 of the functional component 20, and the sensor element 22 detects an output voltage corresponding to the deformation of the tire during driving, and the wear amount of the tread portion 1 is detected based on the output voltage. In addition, an acceleration sensor or a magnetic sensor can also be used.

[0047] like Figure 2 As shown, when a first projection area S0 formed by projecting the contact surface 21 of the functional component 20 onto the tread of the tread portion 1 is specified, the groove area ratio GR0 in the first projection area S0 in the new tire state is set within the range of 50.0% ≤ GR0 ≤ 100.0%. The groove area ratio GR0 in the first projection area S0 in the new tire state refers to the ratio of the groove area to the total area of ​​the first projection area S0 projected onto the tread in the new tire state.

[0048] In this way, when the functional component 20 is set on the back side of the tread portion 1, by setting the functional component 20 at a position where the overlap with the groove is as large as possible, the excessive impact received by the tire from the road surface when the tire touches the ground is not easily transmitted to the functional component 20, and the physical quantity changes caused by the deformation of the tread portion 1 can be detected with high precision, thereby improving the sensing accuracy of the functional component 20 and improving the measurement performance of the tire information.

[0049] Here, if the groove area ratio GR0 in the first projection area S0 of the tire in the new state is less than 50%, the groove component between the road surface and the contact surface 21 of the functional component 20 decreases, so the effect of improving the sensing accuracy of the functional component 20 decreases. The groove area ratio GR0 in the first projection area S0 of the tire in the new state is particularly preferably in the range of 75.0%≤GR0≤100.0%.

[0050] In addition, if Figure 2As shown, when a second projection area S formed by projecting the sensor element 22 onto the tread of the tread portion 1 is specified, the groove area ratio GR in the second projection area S when the tire is new can be in the range of 80.0% ≤ GR ≤ 100.0%. The groove area ratio GR in the second projection area S when the tire is new refers to the ratio of the groove area to the total area of ​​the second projection area S projected onto the tread when the tire is new. In this way, by setting the sensor element 22 at a position where the overlap with the groove is as large as possible, the excessive impact received from the road surface when the tire contacts the ground is not easily transmitted to the sensor element 22, and the physical quantity change caused by the deformation of the tread portion 1 can be detected with high precision, thereby improving the sensing accuracy of the functional component 20.

[0051] Here, if the groove area ratio GR in the second projection area S of the tire in the new state is less than 80%, the groove component between the road surface and the sensor element 22 of the functional component 20 decreases, so the effect of improving the sensing accuracy of the functional component 20 decreases. The groove area ratio GR in the second projection area S of the tire in the new state is particularly preferably in the range of 95.0%≤GR≤100.0%.

[0052] like Figure 6 As shown, when a first three-dimensional area V0 is defined and the first three-dimensional area V0 is formed by a trajectory when the first projection area S0 is moved from the tread position of the new tire to the contact surface 21 by the rubber thickness of the tread portion 1, the groove volume ratio GRV0 in the first three-dimensional area V0 can be within the range of 50.0% ≤ GRV0 ≤ 100.0%. The rubber thickness of the tread portion 1 refers to the thickness of the tread rubber layer laminated outside the reinforcement layer such as the belt layer 7 or the belt cover layer 8 buried in the tread portion 1, and refers to the thickness from the tread of the tread portion 1 to the reinforcement layer. The groove volume ratio GRV0 in the first three-dimensional area V0 refers to the ratio of the groove volume to the total volume of the first three-dimensional area V0. In this way, by increasing the volume of the groove in the area directly above the functional component 20 as much as possible, the excessive impact received from the road surface when the tire contacts the ground is not easily transmitted to the functional component 20, and the physical quantity change caused by the deformation of the tread portion 1 can be detected with high accuracy, so that the sensing accuracy of the functional component 20 can be improved.

[0053] Here, if the groove volume ratio GRV0 in the first three-dimensional region V0 is less than 50%, the groove component between the road surface and the contact surface 21 of the functional component 20 decreases, thereby reducing the effect of improving the sensing accuracy of the functional component 20. The groove volume ratio GRV0 in the first three-dimensional region V0 is particularly preferably in the range of 85.0% ≤ GRV0 ≤ 100.0%.

[0054] In addition, if Figure 6As shown, when a second three-dimensional area V is specified, and the second three-dimensional area V is formed by a trajectory when the second projection area S is moved from the tread position of the new tire to the contact surface 21 by the rubber thickness of the tread portion 1, the groove volume ratio GRV in the second three-dimensional area V can be in the range of 60.0% ≤ GRV ≤ 100.0%. The groove volume ratio GRV in the second three-dimensional area V refers to the ratio of the groove volume to the total volume of the second three-dimensional area V. In this way, by increasing the volume of the groove in the area directly above the sensor element 22 as much as possible, the excessive impact received from the road surface when the tire contacts the ground is not easily transmitted to the sensor element 22, and the physical quantity change caused by the deformation of the tread portion 1 can be detected with high precision, thereby improving the sensing accuracy of the functional component 20.

[0055] Here, if the groove volume ratio GRV in the second three-dimensional region V is less than 60%, the groove component between the road surface and the sensor element 22 of the functional component 20 decreases, thereby reducing the effect of improving the sensing accuracy of the functional component 20. The groove volume ratio GRV in the second three-dimensional region V is particularly preferably in the range of 80.0% ≤ GRV ≤ 100.0%.

[0056] Furthermore, the change rate RGR0 of the groove area ratio GR0 in the first projection area S0 under the 80% wear state of the tread portion 1 (i.e., the state in which the residual groove is 20%) relative to the groove area ratio GR0 in the first projection area S0 under the new tire state can be within ±20%. For example, when the groove area ratio GR0 in the first projection area S0 under the new tire state is 60%, the groove area ratio GR0 in the first projection area S0 under the 80% wear state of the tread portion 1 can be in the range of 48% to 72%. The groove area ratio GR0 in the first projection area S0 changes as the wear of the tread portion 1 progresses, and decreases in ordinary tires. By specifying the change rate RGR0 as described above, the change in the groove area ratio GR0 in the first projection area S0 due to wear will become smaller, so the effect of improving the sensing accuracy will continue from the new state to the worn state, so that a higher sensing accuracy can be continuously obtained within the wear life of the tire.

[0057] Here, if the change rate RGR0 of the groove area ratio GR0 in the first projection area S0 in the tread portion 1 80% worn state relative to the groove area ratio GR0 in the first projection area S0 in the new tire state exceeds the range of ±20%, the variation of the sensing accuracy during the tire wear life becomes larger.

[0058] Similarly, the change rate RGR of the groove area ratio GR in the second projection area S of the tread portion 1 when the tire is 80% worn relative to the groove area ratio GR in the second projection area S of the tire when the tire is new can be within ±10%. For example, when the groove area ratio GR in the second projection area S of the tire is 85% in the new state, the groove area ratio GR in the second projection area S of the tread portion 1 when the tire is 80% worn can be in the range of 76.5% to 93.5%. The groove area ratio GR in the second projection area S changes as the wear of the tread portion 1 progresses, and decreases in ordinary tires. By specifying the change rate RGR as described above, the change in the groove area ratio GR in the second projection area S due to wear will become smaller, so the effect of improving the sensing accuracy will continue from the new state to the worn state, so that a high sensing accuracy can be continuously obtained within the wear life of the tire.

[0059] Here, if the change rate RGR of the groove area ratio GR in the second projection area S when the tread portion 1 is 80% worn relative to the groove area ratio GR in the second projection area S when the tire is new exceeds the range of ±10%, the variation in sensing accuracy during the tire wear life becomes larger.

[0060] like Figure 2 As shown, in a tire in which a circumferential main groove 11A extending in the circumferential direction of the tire is formed in the tread portion 1, when the tire is new, more than 80% of the groove area included in the second projection area S can come from the circumferential main groove 11A. For example, when the second projection area S is completely included in the inner side of the circumferential main groove 11A, 100% of the groove area included in the second projection area S comes from the circumferential main groove 11A. By arranging the sensor element 22 in the area directly above the circumferential main groove 11, the sensing accuracy of the functional component 20 can be effectively improved, and this effect can be continuously obtained.

[0061] In a tire in which the belt layer 7 is embedded in the tread portion 1, the second projection area S may be arranged in the extended area of ​​the belt layer 7. Figure 1 In the tire meridian section shown, the sensor element 22 of the functional component 20 can be arranged in the extended area of ​​the belt layer 7. By adopting this arrangement, the deformation of the tread portion 1 caused by contact with the ground can be detected efficiently. Figure 2 As shown, the distance between the tire center line CL and the center position O of the second projection area S in the tire width direction is preferably 30% or less of the maximum width of the belt layer 7 .

[0062] like Figure 2As shown in FIG. 1 , a circumferential main groove 11A extending in the tire circumferential direction is formed in the tread portion 1, and a wear indicator 15 formed by a groove bottom protrusion is formed in each circumferential main groove 11A. In this way, in a tire having a wear indicator 15 formed in the circumferential main groove 11A, the wear indicator 15 can be arranged at a position outside the range X of 20 mm from the center position O of the second projection area S in the tire circumferential direction. If the wear indicator 15 is present in the circumferential main groove 11A around the sensor element 22, an excessive impact received from the road surface when the tire contacts the ground is easily transmitted to the sensor element 22, so by keeping such a wear indicator 15 away from the sensor element 22, the sensing accuracy of the functional component 20 can be improved.

[0063] like Figure 7 As shown, the pneumatic tire may have a marking 23 capable of identifying the position of the sensor element 22 in the tire side region (the region where the brand is displayed on the outer surface of the sidewall portion 2). The marking 23 may be arranged within a range of ±10° from the center position O of the second projection region S in the tire circumferential direction with the tire rotation axis A as the center. Thus, the position of the sensor element 22 can be identified from the outside of the tire, thereby improving the workability of installing or maintaining the functional component 20. In addition, the marking 23 is preferably a dedicated indicator for identifying the position of the sensor element 22, but depending on the situation, an existing indicator such as a mark for a wear indicator may also be used as the marking 23.

[0064] Example

[0065] A tire of a comparative example and embodiments 1 to 9 was prepared, wherein the tire size was 225 / 45ZR18, and a functional component having a sensor function for detecting tire information was provided on the back of the tread portion, the functional component having a sensor function obtained by using a piezoelectric element as a sensor element, and in the above-mentioned tire, when a first projection area S0 formed by projecting a contact surface of the functional component onto a tread surface of the tread portion, a second projection area S formed by projecting the sensor element of the functional component onto the tread surface of the tread portion, a first three-dimensional area V0 formed by a trajectory when the first projection area S0 is moved from a tread surface position of the tire in a new state toward the contact surface by the amount of the rubber thickness of the tread portion, and a trajectory when the second projection area S is moved from a tread surface position of the tire in a new state toward the contact surface by the amount of the rubber thickness of the tread portion When the second three-dimensional area V formed by the tire track is formed, the groove area ratio GR0 in the first projection area S0 when the tire is new, the groove area ratio GR in the second projection area S when the tire is new, the groove volume ratio GRV0 in the first three-dimensional area V0, the groove volume ratio GRV in the second three-dimensional area V, the change rate RGR0 of the groove area ratio GR0 in the first projection area S0 when the tread is 80% worn relative to the groove area ratio GR0 in the first projection area S0 when the tire is new, the change rate RGR of the groove area ratio GR in the second projection area S when the tread is 80% worn relative to the groove area ratio GR in the second projection area S when the tire is new, and the distance from the center position of the second projection area S to the wear indicator are set as shown in Table 1. In addition, the functional component is installed on the back of the tread through the container.

[0066] The sensor accuracy of these test tires when new and when worn was evaluated by the following test method, and the results are collectively shown in Table 1.

[0067] Sensing accuracy:

[0068] Each test tire was assembled on a wheel with a rim size of 18×7.5JJ and installed on a roller testing machine. A driving test was carried out with the air pressure set to 230 kPa, the load set to 60% of the maximum load capacity, and the speed set to 30 km / h. The output detected by the sensor element (piezoelectric element) was recorded. Figure 8This is a diagram showing an example of an output waveform from a piezoelectric element. In this output waveform, when the portion in the tread where the functional component is provided is grounded, as time T passes, a peak on the negative side and a peak on the positive side are sequentially formed in the output of the piezoelectric element, thereby obtaining a peak-to-peak value V. Then, the average value Vave and the standard deviation σ of the peak-to-peak value V of the output waveform obtained by measuring 10 times are obtained, and the coefficient of variation CV (CV = σ / Vave) is calculated. The evaluation result is expressed as an index using the reciprocal of the coefficient of variation CV, with the comparative example being set to 100. The larger the index value, the better the sensing accuracy. This sensing accuracy is evaluated when the tire is new and when the tread is worn 50%. It should be noted that the sensing accuracy when it is new and when it is worn are both index values ​​based on the comparative example when it is new.

[0069] [Table 1]

[0070]

[0071] As can be seen from Table 1, in comparison with the comparative example, the sensing accuracy of the functional components of the tires of Examples 1 to 9 is good.

[0072] Description of Reference Numerals

[0073] 1: Tread

[0074] 2: Side wall

[0075] 3: Bead

[0076] 4: Carcass layer

[0077] 5: Bead core

[0078] 6: Bead core

[0079] 7: Belt

[0080] 8: With cover layer

[0081] 11: Circumferential groove

[0082] 11A: Circumferential main groove

[0083] 11B: Circumferential groove

[0084] 12A, 12B: Chamfered part

[0085] 13: Shoreline

[0086] 14: Horizontal groove

[0087] 20: Functional components

[0088] 21: Contact surface

[0089] 22: Sensor element

[0090] 23: Engraving

[0091] 30: Containment

Claims

1. A tire having a functional component having a sensor function for detecting tire information on the back side of a tread portion, It is characterized in that The functional component has a contact surface that contacts the back side of the tread portion. When a first projection area S0 formed by projecting the contact surface onto the tread surface of the tread portion is specified, the groove area ratio GR0 within the first projection area S0 when the tire is in a new state is in the range of 50.0%≤GR0≤100.0%.

2. The tire according to claim 1, It is characterized in that The functional component has a sensor element for detecting tire information, and the sensor element is arranged in the contact surface. When a second projection area S formed by projecting the sensor element onto the tread surface of the tread portion is specified, the groove area ratio GR in the second projection area S of the tire in a new state is in the range of 80.0%≤GR≤100.0%.

3. The tire according to claim 1 or 2, It is characterized in that When a first three-dimensional area V0 is specified and formed by a trajectory of moving the first projection area S0 from the tread position of a new tire toward the contact surface by the rubber thickness of the tread portion, the groove volume ratio GRV0 within the first three-dimensional area V0 is within the range of 50.0%≤GRV0≤100.0%.

4. The tire according to claim 2, It is characterized in that When a second three-dimensional area V is specified and formed by a trajectory of moving the second projection area S from the tread position of the new tire toward the contact surface by the rubber thickness of the tread portion, the groove volume ratio GRV within the second three-dimensional area V is in the range of 60.0% ≤ GRV ≤ 100.0%.

5. The tire according to any one of claims 1 to 4, It is characterized in that A change rate RGR0 of the groove area ratio GR0 in the first projection region S0 when the tread portion is 80% worn relative to the groove area ratio GR0 in the first projection region S0 when the tire is new is within ±20%.

6. The tire according to claim 2 or 4, It is characterized in that A change rate RGR of the groove area ratio GR in the second projection region S when the tread portion is 80% worn relative to the groove area ratio GR in the second projection region S when the tire is new is within ±10%.

7. The tire according to claim 2, 4 or 6, wherein the tread portion of the tire has a circumferential main groove extending in the tire circumferential direction. It is characterized in that When the tire is in a new state, more than 80% of the groove area included in the second projection area S comes from the circumferential main groove.

8. The tire according to claim 2, 4, 6 or 7, wherein a belt layer is embedded in the tread portion. It is characterized in that The second projection area S is arranged in the extension area of ​​the belt layer.

9. The tire according to claim 2, 4, 6, 7 or 8, wherein the tire has a circumferential main groove extending in the tire circumferential direction formed in the tread portion, and a wear indicator formed by a groove bottom protrusion is formed in the circumferential main groove, It is characterized in that The wear indicator is arranged at a position outside a range of 20 mm from the center position of the second projection area S in the tire circumferential direction.

10. A tyre according to claim 2, 4, 6, 7, 8 or 9, It is characterized in that The tire side region has a marking capable of identifying the position of the sensor element, and the marking is arranged within a range of ±10° from the center position of the second projection area S in the tire circumferential direction with the tire rotation axis as the center.

11. The tire according to any one of claims 1 to 10, It is characterized in that A housing for housing the functional component is fixed to the back surface of the tread portion, and the functional component is housed in the housing.

12. The tire according to claim 11, It is characterized in that The housing body is fixed to the back surface of the tread portion by an adhesive.

13. The tire according to claim 11 or 12, It is characterized in that The housing is made of vulcanized rubber.

14. The tire according to any one of claims 1 to 13, It is characterized in that The functional component has a sensor function obtained by using a piezoelectric element as a sensor element.

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