Patent Application
20230083074
The present technology relates to a pneumatic tire embedded with a transponder and particularly relates to a pneumatic tire that can provide improved transponder communication performance and transponder durability while suppressing the degradation of the rolling resistance of the tire.
For pneumatic tires, embedment of an RFID (radio frequency identification) tag (transponder) in a tire has been proposed (see, for example, Japan Unexamined Patent Publication No. H07-137510). In a case where a transponder is embedded in the tire and the heat build-up of a rubber member in a periphery of the transponder is low during travel in a low-temperature environment, the temperature of the rubber member does not rise, and the transponder may be damaged due to tire deformation. On the other hand, in a case where the heat build-up of the rubber member in the periphery of the transponder is too high, the rolling resistance of the tire degrades. Further, in a case where the transponder is disposed on an inner side in a tire width direction of a carcass layer, radio waves are blocked by a tire component (for example, a metal member such as a carcass or reinforcement made of steel) during communication with the transponder, and the communication performance of the transponder may degrade.
The present technology provides a pneumatic tire that can provide improved transponder communication performance and transponder durability while suppressing the degradation of the rolling resistance of the tire.
A pneumatic tire according to a first embodiment includes: a tread portion extending in a tire circumferential direction and having an annular shape; a pair of sidewall portions disposed on both sides of the tread portion; a pair of bead portions disposed on an inner side in a tire radial direction of the sidewall portions; and a carcass layer mounted between the pair of bead portions. The pneumatic tire is embedded with a transponder on an outer side in a tire width direction of the carcass layer. A tan δout (−20° C.) at −20° C. of a rubber member having a largest storage modulus at 20° C. of rubber members located on an outer side in the tire width direction of the transponder is in a range of from 0.1 to 0.7.
A pneumatic tire according to a second embodiment includes: a tread portion extending in a tire circumferential direction and having an annular shape; a pair of sidewall portions disposed on both sides of the tread portion; a pair of bead portions disposed on an inner side in a tire radial direction of the sidewall portions; and a carcass layer mounted between the pair of bead portions. The pneumatic tire is embedded with a transponder on an outer side in a tire width direction of the carcass layer. A tan δin (−20° C.) at −20° C. of a rubber member having a largest storage modulus at 20° C. of rubber members located on an inner side in the tire width direction of the transponder is in a range of from 0.1 to 0.7.
The first embodiment, which has the transponder embedded on the outer side in the tire width direction of the carcass layer, has no tire component that blocks radio waves during communication with the transponder, ensuring the communication performance of the transponder. The tan δout (−20° C.) at −20° C. of the rubber member having the largest storage modulus at 20° C. of the rubber members located on the outer side in the tire width direction of the transponder is in the range of from 0.1 to 0.7. Typically, in a low-temperature environment, the higher the tan δ of the rubber member, the higher the heat build-up, but the first embodiment sets the values of the tan δ of the rubber members located on the outer side in the tire width direction of the transponder in the range described above and can thereby maintain the heat build-up of the rubber members during travel in a low-temperature environment. Accordingly, the rubber members do not become brittle, and damage to the transponder due to tire deformation can be prevented. This can suppress the degradation of the rolling resistance of the tire and improve the durability of the transponder in a low-temperature environment.
The second embodiment, which has the transponder embedded on the outer side in the tire width direction of the carcass layer, has no tire component that blocks radio waves during communication with the transponder, ensuring the communication performance of the transponder. The tan δin (−20° C.) at −20° C. of the rubber member having the largest storage modulus at 20° C. of the rubber members located on the inner side in the tire width direction of the transponder is in the range of from 0.1 to 0.7. Typically, in a low-temperature environment, the higher the tan δ of the rubber member, the higher the heat build-up, but the second embodiment sets the values of the tan δ of the rubber members located on the inner side in the tire width direction of the transponder in the range described above and can thereby maintain the heat build-up of the rubber members during travel in a low-temperature environment. Accordingly, the rubber members do not become brittle, and damage to the transponder due to tire deformation can be prevented. This can suppress the degradation of the rolling resistance of the tire and improve the durability of the transponder in a low-temperature environment.
In the pneumatic tire according to the first embodiment, the tan δout (−20° C.) at −20° C. and a tan δout (0° C.) at 0° C. of the rubber member having the largest storage modulus at 20° C. of the rubber members located on the outer side in the tire width direction of the transponder preferably satisfy a relationship 0.5≤tan δout (0° C.)/tan δout (−20° C.)≤0.95. This can effectively improve the durability of the transponder while effectively suppressing the degradation of the rolling resistance of the tire.
Preferably, the transponder is covered with a covering layer, and a tan δc (−20° C.) at −20° C. of the covering layer and the tan δout (−20° C.) satisfy a relationship 0.3≤tan δc (−20° C.)/tan δout (−20° C.)≤0.9. This brings the tan δ of the covering layer and that of a rubber member adjacent to the covering layer closer together, can improve the heat retaining properties of the covering layer for the transponder, and thus can effectively improve the durability of the transponder.
In the pneumatic tire according to the second embodiment, the tan δin (−20° C.) at −20° C. and a tan δin (0° C.) at 0° C. of the rubber member having the largest storage modulus at 20° C. of the rubber members located on the inner side in the tire width direction of the transponder preferably satisfy a relationship 0.5≤tan δin (0° C.)/tan δin (−20° C.)≤0.95. This can effectively improve the durability of the transponder while effectively suppressing the degradation of the rolling resistance of the tire.
Preferably, the transponder is covered with a covering layer, and a tan δc (−20° C.) at −20° C. of the covering layer and the tan δin (−20° C.) satisfy a relationship 0.3≤tan δc (−20° C.)/tan δin (−20° C.)≤0.9. This brings the tan δ of the covering layer and that of a rubber member adjacent to the covering layer closer together, can improve the heat retaining properties of the covering layer for the transponder, and thus can effectively improve the durability of the transponder.
In the pneumatic tire according to the first or second embodiments, preferably, the transponder is covered with a covering layer, and a storage modulus E′c (−20° C.) at −20° C. of the covering layer is in a range of from 3 MPa to 17 MPa. This can improve the protective effect of the covering layer on the transponder, and effectively improve the durability of the transponder.
Preferably, the transponder is covered with a covering layer, and the covering layer has a relative dielectric constant of 7 or less. Accordingly, the transponder is protected by the covering layer, allowing the durability of the transponder to be improved and also ensuring radio wave transmissivity of the transponder to allow the communication performance of the transponder to be effectively improved.
Preferably, the transponder is covered with a covering layer, and the covering layer is formed of a rubber or an elastomer and 20 phr or more of a white filler. This enables the relative dielectric constant of the covering layer to be relatively small and effectively improve the communication performance of the transponder.
The white filler preferably includes from 20 phr to 55 phr of calcium carbonate. This enables the relative dielectric constant of the covering layer to be relatively small and effectively improve the communication performance of the transponder.
A center of the transponder is preferably disposed 10 mm or more away in the tire circumferential direction from a splice portion of a tire component. This can effectively improve the durability of the tire.
The transponder is preferably disposed between a position 15 mm away from and on an outer side in the tire radial direction of an upper end of a bead core of the bead portion and a tire maximum width position. Accordingly, the transponder is disposed in a region where the stress amplitude during travel is small, and this can effectively improve the durability of the transponder.
A distance between a cross-sectional center of the transponder and a tire outer surface is preferably 2 mm or more. This can effectively improve the durability of the tire as well as improve the scratch resistance of the tire.
Preferably, the transponder is covered with a covering layer, and the covering layer has a thickness of from 0.5 mm to 3.0 mm. This can effectively improve the communication performance of the transponder without making the tire outer surface uneven.
Preferably, the transponder includes an IC (integrated circuit) substrate that stores data and an antenna that transmits and receives data, and the antenna has a helical shape. This allows the transponder to follow deformation of the tire during travel, improving the durability of the transponder.
According to the first or second embodiment, the storage modulus E′ and the loss tangent tan δ are measured at a designated temperature, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±2% in a tensile deformation mode using a viscoelastic spectrometer in accordance with JIS (Japanese Industrial Standard)-K6394.
A configuration according to a first embodiment will be described in detail below with reference to the accompanying drawings.
As illustrated in
At least one carcass layer 4 (one layer in
On the other hand, a plurality of belt layers 7 (two layers in
To improve high-speed durability, at least one belt cover layer 8 (two layers in
In the pneumatic tire described above, both ends 4e of the carcass layer 4 are each folded back from a tire inner side to a tire outer side around the bead core 5, wrapping around the bead core 5 and the bead filler 6. The carcass layer 4 includes: a body portion 4A corresponding to a portion extending from the tread portion 1 through each of the sidewall portions 2 to each of the bead portions 3; and a turned up portion 4B corresponding to a portion turned up around the bead core 5 at each of the bead portions 3 and extending toward a sidewall portion 2 side.
A tire inner surface includes an innerliner layer 9 disposed along the carcass layer 4. The tread portion 1 includes a cap tread rubber layer 11, the sidewall portion 2 includes a sidewall rubber layer 12, and the bead portion 3 includes a rim cushion rubber layer 13.
The pneumatic tire described above includes a transponder 20 embedded in a portion on an outer side in a tire width direction of the carcass layer 4. The transponder 20 extends along the tire circumferential direction. The transponder 20 may be inclined at an angle in a range of from −10° to 10° with respect to the tire circumferential direction.
The transponder 20 may be, for example, a radio frequency identification (RFID) tag. As illustrated in
The overall shape of the transponder 20 is not particularly limited, and can be, for example, a pillar-like shape or plate-like shape as illustrated in
Further, in the pneumatic tire described above, of rubber members located on the outer side in the tire width direction of the transponder 20 (the sidewall rubber layer 12 and the rim cushion rubber layer 13 in
Note that while the embodiment of
The pneumatic tire described above, which has the transponder 20 embedded on the outer side in the tire width direction of the carcass layer 4, has no tire component that blocks radio waves during communication with the transponder 20, ensuring the communication performance of the transponder 20. Further, the tan δout (−20° C.) at −20° C. of the rubber member having the largest storage modulus E′out (20° C.) at 20° C. of the rubber members located on the outer side in the tire width direction of the transponder 20 is in the range of from 0.1 to 0.7, and thus the heat build-up of the rubber member can be maintained appropriately during travel in a low-temperature environment. Accordingly, the rubber member does not become brittle, and damage to the transponder 20 due to tire deformation can be prevented. This can suppress the degradation of the rolling resistance of the tire and improve the durability of the transponder 20 in a low-temperature environment.
Here, in a case where the value of the tan δout (−20° C.) is smaller than the lower limit value, the durability of the transponder tends to degrade due to tire deformation during travel, whereas in a case where the value of the tan δout (−20° C.) is larger than the upper limit value, the rolling resistance of the tire tends to degrade.
Note that of rubber members located on an inner side in the tire width direction of the transponder 20 (a coating rubber of the carcass layer 4, the bead filler 6, and the innerliner layer 9 in
In the pneumatic tire described above, the tan δout (−20° C.) at −20° C. and a tan δout (0° C.) at 0° C. of the outer member preferably satisfy the relationship 0.5≤tan δout (0° C.)/tan δout (−20° C.)≤0.95. The tan δ of the outer member at each temperature thus satisfying the relationship formula described above allows for effectively improving the durability of the transponder 20 while effectively suppressing the degradation of the rolling resistance of the tire. Here, in a case where the value of tan δout (0° C.)/tan δout (−20° C.) is smaller than the lower limit value, the heat build-up of the outer member decreases, the heat insulating effect thereof on the transponder 20 decreases, and the durability of the transponder 20 tends to degrade. Conversely, in a case where the value of tan δout (0° C.)/tan δout (−20° C.) is larger than the upper limit value, there is little temperature dependence of the tan δ of the outer member, and the rolling resistance of the tire slightly degrades.
Further, the transponder 20 is preferably disposed in a placement region in the tire radial direction between a position P1 15 mm away from and on the outer side in the tire radial direction of an upper end 5e (an end portion on the outer side in the tire radial direction) of the bead core 5 and a position P2 where the tire width is greatest. That is, the transponder 20 is preferably disposed in a region S1 illustrated in
As illustrated in
Note that while the embodiment of
As illustrated in
Further, the transponder 20 is preferably covered with the covering layer 23. The covering layer 23 covers the transponder 20 completely so as to sandwich both front and rear surfaces of the transponder 20. The covering layer 23 may be formed from a rubber having physical properties identical to those of a rubber forming the sidewall rubber layer 12 or the rim cushion rubber layer 13, or may be formed from a rubber having different physical properties. With the transponder 20 protected by the covering layer 23, the durability of the transponder 20 can be improved.
The covering layer 23 covering the transponder 20 is described in detail below. Physical properties of the covering layer 23 are preferably set such that the tan δc (−20° C.) at −20° C. of the covering layer 23 and the tan δout (−20° C.) of the outer member satisfy the relationship 0.3≤tan δc (−20° C.)/tan δout (−20° C.)≤0.9. By thus setting the physical properties of the covering layer 23 with regard to the outer member, the tan δ of the covering layer 23 and that of a rubber member adjacent to the covering layer 23 (for example, the rim cushion rubber layer 13) are brought closer together, the heat retaining properties of the covering layer 23 for the transponder 20 can be improved, and thus the durability of the transponder 20 can be effectively improved.
Further, the storage modulus E′c (−20° C.) at −20° C. of the covering layer 23 is preferably in the range of from 3 MPa to 17 MP a. By thus setting the physical properties of the covering layer 23, the protective effect of the covering layer 23 on the transponder 20 can be improved, and effectively improve the durability of the transponder 20. Here, in a case where the storage modulus E′c at −20° C. of the covering layer 23 is smaller than the lower limit value of the range described above, the rigidity of the covering layer 23 decreases, making the protective effect thereof on the transponder 20 tend to decrease, whereas in a case where the storage modulus E′c at −20° C. of the covering layer 23 is larger than the upper limit value of the range described above, the rigidity of the covering layer 23 increases, the covering layer 23 becomes brittle, and the covering layer 23 becomes prone to breakage, and thus the transponder 20 may be damaged.
The composition of the covering layer 23 is preferably a rubber or an elastomer and 20 phr or more of a white filler. Such a composition of the covering layer 23 can lower the relative dielectric constant of the covering layer 23, compared to a composition containing carbon, and effectively improve the communication performance of the transponder 20. Note that “phr” means weight parts per 100 parts by weight of a rubber component (elastomer).
The white filler forming the covering layer 23 preferably includes from 20 phr to 55 phr of calcium carbonate. This can lower the relative dielectric constant of the covering layer 23 and effectively improve the communication performance of the transponder 20. However, too much calcium carbonate in the white filler makes the covering layer 23 brittle and lowers its strength, and this is not preferable. The covering layer 23 can optionally include 20 phr or less of a silica (white filler) or 5 phr or less of a carbon black in addition to calcium carbonate. An addition of a small amount of silica and carbon black can lower the relative dielectric constant of the covering layer 23 while ensuring the strength thereof.
The covering layer 23 preferably has a relative dielectric constant of 7 or less, and more preferably of from 2 to 5. By thus setting the relative dielectric constant of the covering layer 23 as appropriate, the radio wave transmissivity of the transponder 20 during emission of radio waves can be ensured, and the communication performance of the transponder 20 can be effectively improved. Note that the rubber forming the covering layer 23 has a relative dielectric constant of from 860 MHz to 960 MHz at ambient temperature. Here, the ambient temperature is 23±2° C. and 60%±5% RH in accordance with the standard conditions of the JIS standard. The relative dielectric constant of the rubber is measured in accordance with an electrostatic capacitance method after a 24-hour treatment at 23° C. and 60% RH. The range from 860 MHz to 960 MHz described above corresponds to allocated frequencies of the RFID in a current UHF (ultra high frequency) band, but in a case where the allocated frequencies change, it is only required that the relative dielectric constant in the range of the allocated frequencies be specified as described above.
A thickness t of the covering layer 23 is preferably from 0.5 mm to 3.0 mm, and more preferably from 1.0 mm to 2.5 mm. Here, a thickness t of the covering layer 23 is a rubber thickness at a position including the transponder 20, and is, for example, a rubber thickness obtained by summing a thickness t1 and a thickness t2 on a straight line extending through the center of the transponder 20 and orthogonally to a tire outer surface, as illustrated in
While the embodiment described above illustrates an example in which the end 4e of the turned up portion 4B of the carcass layer 4 is disposed at or near an upper end 6e of the bead filler 6, no such limitation is intended, and the end 4e of the turned up portion 4B of the carcass layer 4 can be disposed at any height. For example, the end 4e of the turned up portion 4B of the carcass layer 4 may be disposed on a side of the bead core 5. In such a low turn-up structure, the transponder 20 can be disposed between the bead filler 6 and the sidewall rubber layer 12 or the rim cushion rubber layer 13. Here, the rubber member adjacent on the outer side in the tire width direction of the covering layer 23 is the sidewall rubber layer 12 or the rim cushion rubber layer 13.
Next, a configuration according to a second embodiment will be described. A pneumatic tire according to the second embodiment, as with the first embodiment, has a tire structure as illustrated in
In the pneumatic tire according to a second embodiment, of rubber members located on the inner side in the tire width direction of the transponder 20 (a coating rubber of the carcass layer 4, the bead filler 6, and the innerliner layer 9 in
Note that while the embodiment of
The pneumatic tire described above, which has the transponder 20 embedded on the outer side in the tire width direction of the carcass layer 4, has no tire component that blocks radio waves during communication with the transponder 20, ensuring the communication performance of the transponder 20. Further, the tan δin (−20° C.) at −20° C. of the rubber member having the largest storage modulus E′in (20° C.) at 20° C. of the rubber members located on the inner side in the tire width direction of the transponder 20 is in the range of from 0.1 to 0.7, and thus the heat build-up of the rubber member can be maintained appropriately during travel in a low-temperature environment. Accordingly, the rubber member does not become brittle, and damage to the transponder 20 due to tire deformation can be prevented. This can suppress the degradation of the rolling resistance of the tire and improve the durability of the transponder 20 in a low-temperature environment.
Here, in a case where the value of the tan δin (−20° C.) is smaller than the lower limit value, the durability of the transponder tends to degrade due to tire deformation during travel, whereas in a case where the value of the tan δin (−20° C.) is larger than the upper limit value, the rolling resistance of the tire tends to degrade.
Note that of rubber members located on the outer side in the tire width direction of the transponder 20 (the sidewall rubber layer 12 and the rim cushion rubber layer 13 in
In the pneumatic tire described above, the tan δin (−20° C.) at −20° C. and a tan in (0° C.) at 0° C. of the inner member preferably satisfy the relationship 0.5≤tan δin (0° C.)/tan δin (−20° C.)≤0.95. The tan δ of the inner member at each temperature thus satisfying the relationship formula described above allows for effectively improving the durability of the transponder 20 while effectively suppressing the degradation of the rolling resistance of the tire. Here, in a case where the value of tan δin (0° C.)/tan δin (−20° C.) is smaller than the lower limit value, the heat build-up of the inner member decreases, the heat insulating effect thereof on the transponder 20 decreases, and the durability of the transponder 20 tends to degrade. Conversely, in a case where the value of tan in (0° C.)/tan δin (−20° C.) is larger than the upper limit value, there is little temperature dependence of the tan δ of the inner member, and the rolling resistance of the tire slightly degrades.
Physical properties of the covering layer 23 covering the transponder 20 in the pneumatic tire described above are preferably set such that the tan δc (−20° C.) at −20° C. of the covering layer 23 and the tan δin (−20° C.) of the inner member satisfy the relationship 0.3≤tan δc (−20° C.)/tan δin (−20° C.)≤0.9. By thus setting the physical properties of the covering layer 23 with regard to the inner member, the tan δ of the covering layer 23 and that of a rubber member adjacent to the covering layer 23 (for example, the rim cushion rubber layer 13) are brought closer together, the heat retaining properties of the covering layer 23 for the transponder 20 can be improved, and thus the durability of the transponder 20 can be effectively improved.
Tires of Comparative Examples 1 to 3 and Examples 1 to 16 were manufactured. The tires were each a pneumatic tire having a tire size of 265/40ZR20 and including: a tread portion extending in a tire circumferential direction and having an annular shape; a pair of sidewall portions disposed on both sides of the tread portion; a pair of bead portions disposed on an inner side in a tire radial direction of the sidewall portions; and a carcass layer mounted between the pair of bead portions, the pneumatic tire being embedded with a transponder. The position in a tire width direction of the transponder, the position in the tire radial direction of the transponder, the tan δout (−20° C.) of an outer member, tan δout (0° C.)/tan δout (−20° C.), the presence of a covering layer, the relative dielectric constant of the covering layer, the thickness of the covering layer, the tan δc (−20° C.) of the covering layer, the storage modulus E′c (−20° C.) of the covering layer, and tan δc (−20° C.)/tan δout (−20° C.) were set as in Table 1 and Table 2.
Comparative Examples 1 to 3 and Examples 1 to 16 used a transponder having a columnar shape, and set the distance in the tire circumferential direction from the center of the transponder to a splice portion of a tire component to 10 mm and the distance from a cross-sectional center of the transponder to a tire outer surface to 2 mm or more.
In Table 1 and Table 2, the position in the tire width direction of the transponder being “inner side” means that the transponder is disposed on an inner side in the tire width direction of the carcass layer, whereas the position in the tire width direction of the transponder being “outer side” means that the transponder is disposed on an outer side in the tire width direction of the carcass layer. In Table 1 and Table 2, the position in the tire radial direction of the transponder corresponds to one of positions A to E illustrated in
In Comparative Examples 2 and 3 and Examples 1 to 16, the outer member is a rim cushion rubber layer. That is, in Table 1 and Table 2, “tan δout (0° C.)/tan δout (−20° C.)” is a ratio of the tan δ of the rim cushion rubber layer, which is the outer member. Further, “tan δc (−20° C.)/tan δout (−20° C.)” is a ratio of the tan δ of the covering layer with respect to the tan δ of the rim cushion rubber layer, which is the outer member. For the sake of convenience, Comparative Example 1 indicates physical properties of the rim cushion rubber layer as those of the outer member.
The test tires were subjected to tire evaluation (durability and rolling resistance) and transponder evaluation (communication performance and durability) in accordance with a test method described below, and the results are indicated together in Table 1 and Table 2.
With each test tire mounted on a wheel of a standard rim, a travel test was performed using a drum testing machine at a temperature of −20° C., an air pressure of 120 kPa, 102% of the maximum load, and a travel speed of 81 km/h, and the distance traveled at the time of a tire failure was measured. Evaluation results are expressed as index values with Comparative Example 2 being assigned an index value of 100. Larger index values indicate superior tire durability. Further, each test tire was checked after the end of traveling for whether the transponder was communicable and whether the same was damaged. The results are indicated in three levels: “Excellent” in a case where the transponder was communicable and not damaged; “Good” in a case where the transponder was communicable but damaged; and “Poor” in a case where the transponder was not communicable.
With each test tire mounted on a wheel of a standard rim, a travel test was performed using a drum testing machine at a speed of 80 km/h and a temperature of −20° C. in accordance with ISO (International Organization for Standardization) 28580, and the rolling resistance was measured. Evaluation results are expressed as index values using reciprocals of measurement values with Comparative Example 2 being assigned an index value of 100. Larger index values indicate lower rolling resistance and superiority.
For each test tire, a communication operation with the transponder was performed using a reader/writer. Specifically, the maximum communication distance was measured with the reader/writer set at a power output of 250 mW and a carrier frequency of from 860 MHz to 960 MHz. Evaluation results are expressed as index values with Comparative Example 2 being assigned an index value of 100. Larger index values indicate superior communication performance.
As can be seen from Table 1 and Table 2 here, the rolling resistance of the tire and the communication performance and durability of the transponder were improved in a well-balanced manner in the pneumatic tires of Examples 1 to 16, compared to Comparative Example 2.
On the other hand, in Comparative Example 1, the transponder was disposed on the inner side in the tire width direction of the carcass layer, and thus the communication performance of the transponder degraded. In Comparative Example 3, the tan δ of the outer member was set higher than the range specified in the first embodiment, and thus the rolling resistance of the tire degraded.
Next, tires of Comparative Examples 21 to 23 and Examples 21 to 36 were manufactured. The tires were each a pneumatic tire having a tire size of 265/40ZR20 and including: a tread portion extending in the tire circumferential direction and having an annular shape; a pair of sidewall portions disposed on both sides of the tread portion; a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions; and a carcass layer mounted between the pair of bead portions, the pneumatic tire being embedded with a transponder. The position in the tire width direction of the transponder, the position in the tire radial direction of the transponder, the tan δin (−20° C.) of an inner member, tan δin (0° C.)/tan δin (−20° C.), the presence of a covering layer, the relative dielectric constant of the covering layer, the thickness of the covering layer, the tan δc (−20° C.) of the covering layer, the storage modulus E′c (−20° C.) of the covering layer, and tan δc (−20° C.)/tan δin (−20° C.) were set as in Table 3 and Table 4.
Comparative Examples 21 to 23 and Examples 21 to 36 used a transponder having a columnar shape, and set the distance in the tire circumferential direction from the center of the transponder to a splice portion of a tire component to 10 mm and the distance from a cross-sectional center of the transponder to a tire outer surface to 2 mm or more.
In Table 3 and Table 4, the position in the tire width direction of the transponder being “inner side” means that the transponder is disposed on the inner side in the tire width direction of the carcass layer, whereas the position in the tire width direction of the transponder being “outer side” means that the transponder is disposed on the outer side in the tire width direction of the carcass layer. Further, in Table 3 and Table 4, the position in the tire radial direction of the transponder corresponds to one of the positions A to E illustrated in
In Comparative Examples 22 and 23 and Examples 21 to 36, the inner member is a bead filler. That is, in Table 3 and Table 4, “tan δin (0° C.)/tan δin (−20° C.)” is a ratio of the tan δ of the bead filler, which is the inner member. Further, “tan δc (−20° C.)/tan δin (−20° C.)” is a ratio of the tan δ of the covering layer with respect to the tan δ of the bead filler, which is the inner member. For the sake of convenience, Comparative Example 21 indicates physical properties of the bead filler as those of the inner member.
The test tires were subjected to tire evaluation (durability and rolling resistance) and transponder evaluation (communication performance and durability) in accordance with a test method described below, and the results are indicated together in Table 3 and Table 4.
With each test tire mounted on a wheel of a standard rim, a travel test was performed using a drum testing machine at a temperature of −20° C., an air pressure of 120 kPa, 102% of the maximum load, and a travel speed of 81 km/h, and the distance traveled at the time of a tire failure was measured. Evaluation results are expressed as index values with Comparative Example 22 being assigned an index value of 100. Larger index values indicate superior tire durability. Further, each test tire was checked after the end of traveling for whether the transponder was communicable and whether the same was damaged. The results are indicated in three levels: “Excellent” in a case where the transponder was communicable and not damaged; “Good” in a case where the transponder was communicable but damaged; and “Poor” in a case where the transponder was not communicable.
With each test tire mounted on a wheel of a standard rim, a travel test was performed using a drum testing machine at a speed of 80 km/h and a temperature of −20° C. in accordance with ISO 28580, and the rolling resistance was measured. Evaluation results are expressed as index values with Comparative Example 22 being assigned an index value of 100. Larger index values indicate lower rolling resistance and superiority.
For each test tire, a communication operation with the transponder was performed using a reader/writer. Specifically, the maximum communication distance was measured with the reader/writer set at a power output of 250 mW and a carrier frequency of from 860 MHz to 960 MHz. Evaluation results are expressed as index values with Comparative Example 22 being assigned an index value of 100. Larger index values indicate superior communication performance.
As can be seen from Table 3 and Table 4 here, the rolling resistance of the tire and the communication performance and durability of the transponder were improved in a well-balanced manner in the pneumatic tires of Examples 21 to 36, compared to Comparative Example 22.
On the other hand, in Comparative Example 21, the transponder was disposed on the inner side in the tire width direction of the carcass layer, and thus the communication performance of the transponder degraded. In Comparative Example 23, the tan δ of the inner member was set higher than the range specified in the second embodiment, and thus the rolling resistance of the tire degraded.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-024640 | Feb 2020 | JP | national |
| 2020-024641 | Feb 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/005210 | 2/12/2021 | WO |
