Tire

Abstract

The invention provides a tire capable of improving the sensing sensitivity of a functional component and improving the 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 0.0% < = GR0lt; 50.0% of the total amount of the composition.

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 tire information measurement performance by increasing the sensing sensitivity of the functional component. 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 impact force and acceleration received by the tire from the road surface when the tire is running as tire information.

[0003] However, tire information such as impact force or acceleration received by the tire from the road surface when the tire is running is greatly affected by the structural characteristics of the part where the functional component is installed. Therefore, depending on the installation position of the functional component, the sensing sensitivity 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 increasing the sensing sensitivity of a functional component and improving the performance of measuring 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 of the tire in a new state is in the range of 0.0%≤GR0<50.0%.

[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 side of the tread portion, by providing the functional component at a position where the overlap with the groove is minimized, the impact received from the road surface when the tire contacts the ground can be efficiently transmitted to the functional component, thereby improving the sensing sensitivity of the functional component and improving the measurement performance of tire information. Sensing sensitivity means the ability to detect the change of physical quantity caused by the impact from the road surface with high sensitivity. By improving the sensing sensitivity, the peak-to-peak value of the output waveform becomes larger, and the time when the physical quantity changes due to the impact from the road surface 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 0.0% ≤ GR < 20.0%. In this way, by arranging the sensor element at a position where the overlap amount with the groove is as small as possible, the impact received from the road surface when the tire contacts the ground is efficiently transmitted to the sensor element, thereby improving the sensing sensitivity of the functional component.

[0018] When a first three-dimensional area V0 is defined and formed by a trajectory of the first projection area S0 moving 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 0.0% ≤ GRV0 < 30.0%. In this way, by minimizing the volume of the groove in the area directly above the functional component, the impact received from the road surface when the tire contacts the ground can be efficiently transmitted to the functional component, thereby improving the sensing sensitivity of the functional component.

[0019] When a second three-dimensional area V is defined and formed by a trajectory of the second projection area S moving 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 0.0% ≤ GRV < 20.0%. In this way, by minimizing the volume of the grooves in the area directly above the sensor element, the impact received from the road surface when the tire contacts the ground is efficiently transmitted to the sensor element, thereby improving the sensing sensitivity 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 ±10%. The groove area ratio GR0 in the first projection area S0 changes as the tread wear 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 sensitivity will continue from the new time to the worn time, so that a high sensing sensitivity 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 ±5%. 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 sensitivity will continue from the new time to the worn time, so that a high sensing sensitivity can be continuously obtained during the tire wear life.

[0022] In a variable pitch tire in which the grooves formed in the tread portion have a repetitive structure that is repeated along the tire circumferential direction and the pitch of the repetitive structure varies along the tire circumferential direction, it is preferred to arrange the second projection area S at a location where the applied pitch is larger than the middle pitch among the plurality of pitches. That is, in the tread portion to which the variable pitch is applied, by arranging the sensor element at a location with relatively high rigidity, the impact received from the road surface when the tire contacts the ground is efficiently transmitted to the sensor element, thereby improving the sensing sensitivity of the functional component.

[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] 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.

[0025] 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.

[0026] 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.

[0027] 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

[0028] Figure 1 It is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention.

[0029] Figure 2 Yes means Figure 1 A top view of the tread portion of a pneumatic tire.

[0030] Figure 3 Yes means Figure 1 A top view of a portion of a pneumatic tire where functional components are disposed.

[0031] Figure 4 yes Figure 3 The IV-IV arrow cross-section diagram.

[0032] Figure 5 It is a three-dimensional diagram showing a functional component and its housing.

[0033] Figure 6 Yes means Figure 1 A three-dimensional cross-sectional view of the tread portion of a pneumatic tire.

[0034] Figure 7 Yes means Figure 1 A side view of a sidewall portion of a pneumatic tire.

[0035] Figure 8 This is a diagram showing an example of an output waveform from a piezoelectric element. DETAILED DESCRIPTION

[0036] 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.

[0037] like Figure 1As shown in the figure, the pneumatic tire of the present embodiment includes a tread portion 1 extending in the circumferential direction of the tire and formed in a ring 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 radially inner side of these sidewall portions 2 in the tire radial direction.

[0038] A carcass layer 4 is provided between the pair of bead portions 3, 3. The 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 of the tire around the bead cores 5 disposed in the respective bead portions 3. On the outer periphery of the bead core 5, a bead apex 6 made of a rubber composition having a triangular cross section is disposed.

[0039] On the other hand, 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 the reinforcing cords are arranged to cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is, for example, set within a 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 cover layer 8 in which reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7. As the reinforcing cords of the cover layer 8, organic fiber cords such as nylon and aramid are preferably used.

[0040] It should be noted that the above-described internal structure of the tire shows a representative example of a pneumatic tire, but is not limited thereto.

[0041] As Figure 2 shown in the figure, four circumferential grooves 11 extending in the tire circumferential direction 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 fine 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, 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 fine groove 11B each have a chamfered portion 12A, 12B, and such chamfered portions 12A, 12B respectively constitute a part of the circumferential main groove 11A and the circumferential fine groove 11B. Therefore, the chamfered portions 12A, 12B are included in the groove area and the groove volume.

[0042] Through the above-described circumferential grooves 11, five rows of land portions 13 are defined on the tread portion 1. And in each of the land portions 13, a plurality of transverse grooves 14 extending in the tire width direction are formed at intervals in the tire circumferential direction. If necessary, groove components such as sipes may be added to the tread portion 1.

[0043] In the above-described pneumatic tire, grooves such as the circumferential grooves 11 and the transverse grooves 14 are formed on the tread surface of the tread portion 1. On the other hand, as Figure 1As 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 .

[0044] 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.

[0045] 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.

[0046] 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 0.0% ≤ GR0 < 50.0%. 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.

[0047] 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 small as possible, the impact received by the tire from the road surface when the tire touches the ground will be efficiently transmitted to the functional component 20, thereby improving the sensing sensitivity of the functional component 20 and improving the measurement performance of the tire information.

[0048] Here, if the groove area ratio GR0 in the first projection area S0 of the tire in the new state is 50% or more, the groove components between the road surface and the contact surface 21 of the functional component 20 increase, so the effect of improving the sensing sensitivity 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 0.0%≤GR0≤20.0%, and more preferably in the range of 0.0%≤GR0≤5.0%.

[0049] In addition, if Figure 2 As 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 0.0% ≤ GR < 20.0%. 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 small as possible, the impact received from the road surface when the tire contacts the ground will be efficiently transmitted to the sensor element 22, thereby improving the sensing sensitivity of the functional component 20.

[0050] Here, if the groove area ratio GR in the second projection area S of the tire in the new state is 20% or more, the groove components between the road surface and the sensor element 22 of the functional component 20 increase, so the effect of improving the sensing sensitivity 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 0.0% ≤ GR0 ≤ 10.0%.

[0051] like Figure 6 As shown, when a first three-dimensional area V0 is defined and the first three-dimensional area V0 is formed by the trajectory of moving the first projection area S0 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 in the range of 0.0% ≤ GRV0 < 30.0%. 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 reducing the volume of the groove existing in the area directly above the functional component 20 as much as possible, the impact received from the road surface when the tire contacts the ground will be efficiently transmitted to the functional component 20, thereby improving the sensing sensitivity of the functional component 20.

[0052] Here, if the groove volume ratio GRV0 in the first three-dimensional region V0 is 30% or more, the groove components between the road surface and the contact surface 21 of the functional component 20 increase, so the effect of improving the sensing sensitivity of the functional component 20 decreases. The groove volume ratio GRV0 in the first three-dimensional region V0 is particularly preferably in the range of 0.0% ≤ GRV0 ≤ 10.0%.

[0053] In addition, if Figure 6 As 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 moves the rubber thickness of the tread portion 1 from the tread position of the new tire to the contact surface 21, the groove volume ratio GRV in the second three-dimensional area V can be in the range of 0.0% ≤ GRV < 20.0%. 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 reducing the volume of the groove in the area directly above the sensor element 22 as much as possible, the impact received from the road surface when the tire contacts the ground will be efficiently transmitted to the sensor element 22, thereby improving the sensing sensitivity of the functional component 20.

[0054] Here, if the groove volume ratio GRV in the second three-dimensional region V is 20% or more, the groove components between the road surface and the sensor element 22 of the functional component 20 increase, so the effect of improving the sensing sensitivity of the functional component 20 decreases. The groove volume ratio GRV in the second three-dimensional region V is particularly preferably in the range of 0.0% ≤ GRV ≤ 10.0%.

[0055] 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 ±10%. For example, when the groove area ratio GR0 in the first projection area S0 under the new tire state is 25%, 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 22.5% to 27.5%. 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 sensitivity will continue from the new state to the worn state, so that a higher sensing sensitivity can be continuously obtained within the wear life of the tire.

[0056] Here, if the change rate RGR0 of the groove area ratio GR0 in the first projection area S0 in the 80% worn state of the tread surface 1 with respect to the groove area ratio GR0 in the first projection area S0 in the new tire state exceeds the range of ±10%, the variation in the sensing sensitivity within the tire wear life becomes large.

[0057] Similarly, the change rate RGR of the groove area ratio GR in the second projection area S in the 80% worn state of the tread surface 1 with respect to the groove area ratio GR in the second projection area S in the new tire state can be within ±5%. For example, when the groove area ratio GR in the second projection area S in the new tire state is 15%, the groove area ratio GR in the second projection area S in the 80% worn state of the tread surface 1 can be in the range of 14.25% to 15.75%. The groove area ratio GR in the second projection area S changes as the tread surface 1 wears, and decreases in a normal tire. By prescribing 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 small, so the effect of improving the sensing sensitivity will continue from the new state to the worn state, enabling a relatively high sensing sensitivity to be continuously obtained within the tire wear life.

[0058] Here, if the change rate RGR of the groove area ratio GR in the second projection area S in the 80% worn state of the tread surface 1 with respect to the groove area ratio GR in the second projection area S in the new tire state exceeds the range of ±5%, the variation in the sensing sensitivity within the tire wear life becomes large.

[0059] In Figure 2 the groove formed in the tread surface 1 has a repeating structure that repeats in the tire circumferential direction, and a variable pitch in which the pitch of the repeating structure varies in the tire circumferential direction. For example, the transverse grooves 13 are repeatedly arranged at intervals in the tire circumferential direction, and the size of the pitch P in the tire circumferential direction changes in the tire circumferential direction. In a tire with such a variable pitch, it is preferable to arrange the second projection area S (i.e., the sensor element 22) at a position where the applied pitch is larger than the intermediate pitch among the multiple pitches. For example, when the size of the pitch P is set to 5 types and P1 < P2 < P3 < P4 < P5, the second projection area S is arranged at a position where the applied pitch is P4 or P5. Additionally, when the size of the pitch P is set to 4 types and P1 < P2 < P3 < P4, the second projection area S is arranged at a position where the applied pitch is P3 or P4.

[0060] In the tread portion 1 to which the variable pitch is applied, by arranging the sensor element 22 at a relatively high rigidity position, the impact received from the road surface when the tire contacts the ground is efficiently transmitted to the sensor element 22, thereby improving the sensing sensitivity of the functional component 20. For the same reason, the JIS-A hardness of the tread rubber layer constituting the tread portion 1 can be 62 or more. The JIS-A hardness mentioned here is a durometer hardness measured at a temperature of 20°C using a type A durometer in accordance with JIS-K6253.

[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 20% or less of the maximum width of the belt layer 7 .

[0062] 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.

[0063] Example

[0064] A tire of a comparative example and embodiments 1 to 8 is prepared, wherein the tire size is 225 / 45ZR18, and a functional component having a sensor function for detecting tire information is 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 the contact surface of the functional component onto the 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 rubber thickness of the tread portion, and a second projection area S formed by moving the second projection area S from a tread surface position of the tire in a new state toward the contact surface When the second three-dimensional area V is formed by the track of the rubber thickness of the tread portion, the groove area ratio GR0 in the first projection area S0 of the tire in the new state, the groove area ratio GR in the second projection area S of the tire in the new state, 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 of the tread portion in the state of 80% wear relative to the groove area ratio GR0 in the first projection area S0 of the tire in the new state, and the change rate RGR of the groove area ratio GR in the second projection area S of the tread portion in the state of 80% wear relative to the groove area ratio GR in the second projection area S of the tire in the new state. In addition, the functional component is installed on the back of the tread portion through the container.

[0065] The sensor sensitivity 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.

[0066] Sensing sensitivity:

[0067] 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 of the peak-to-peak value V of the output waveform obtained by each 10 measurements is calculated. The evaluation result is expressed as an index using the average value of the peak-to-peak value V of the output waveform, with the comparative example being set to 100. The larger the index value, the better the sensing sensitivity. This sensing sensitivity is evaluated when the tire is new and when the tread is worn 50%. It should be noted that the sensing accuracy when new is an index value based on the comparative example when new, and the sensing accuracy when worn is an index value based on the comparative example when worn.

[0068] [Table 1]

[0069]

[0070] As can be seen from Table 1, the tires of Examples 1 to 8 have good sensing sensitivities of the functional components in comparison with the comparative example.

[0071] Description of Reference Numerals

[0072] 1: Tread

[0073] 2: Side wall

[0074] 3: Bead

[0075] 4: Carcass layer

[0076] 5: Bead core

[0077] 6: Bead core

[0078] 7: Belt

[0079] 8: With cover layer

[0080] 11: Circumferential groove

[0081] 11A: Circumferential main groove

[0082] 11B: Circumferential groove

[0083] 12A, 12B: Chamfered part

[0084] 13: Shoreline

[0085] 14: Horizontal groove

[0086] 20: Functional components

[0087] 21: Contact surface

[0088] 22: Sensor element

[0089] 23: Engraving

[0090] 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 0.0%≤GR0<50.0%.

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 0.0%≤GR<20.0%.

3. The tire according to claim 1 or 2, It is characterized in that When a first three-dimensional area V0 is specified and 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 state toward the contact surface by the rubber thickness of the tread portion, the groove volume ratio GRV0 in the first three-dimensional area V0 is in the range of 0.0%≤GRV0<30.0%.

4. The tire according to claim 2, It is characterized in that 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 toward the contact surface by the rubber thickness of the tread portion, the groove volume ratio GRV in the second three-dimensional area V is in the range of 0.0%≤GRV<20.0%.

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 ±10%.

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 ±5%.

7. The tire according to claim 2, 4 or 6, wherein the grooves formed in the tread portion have a repeated structure that is repeated in the tire circumferential direction, and a variable pitch is adopted in which the pitch of the repeated structure changes in the tire circumferential direction. It is characterized in that The second projection area S is arranged at a location where the applied pitch is larger than a middle pitch among the plurality of pitches.

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. A tyre according to claim 2, 4, 6, 7 or 8, 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.

10. The tire according to any one of claims 1 to 9, 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.

11. The tire according to claim 10, It is characterized in that The housing body is fixed to the back surface of the tread portion by an adhesive.

12. The tire according to claim 10 or 11, It is characterized in that The housing is made of vulcanized rubber.

13. The tire according to any one of claims 1 to 12, 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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