PNEUMATIC TIRE

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to Japanese patent application JP 2022-121202, filed on Jul. 29, 2022 and Japanese patent application JP 2022-179835, filed Nov. 9, 2022, the entire contents of each of which is incorporated herein by reference in its entirety.

BACKGROUND
Field

The present disclosure relates to a pneumatic tire having a tread portion.

Background Art

There has conventionally been a known pneumatic tire in which a sound absorbing part is provided on the inner surface of a tread portion in order to reduce road noise. For example, Japanese Laid-Open Patent Publication No. 2019-108034 proposes a pneumatic tire in which protrusions and recesses are formed on the inward surface in the tire radial direction of a sound absorbing part to further reduce road noise.

SUMMARY

According to an aspect of the present disclosure, a pneumatic tire can include a tread portion, wherein: a sponge-like sound absorbing member can be firmly attached to an inner surface of the tread portion; the sound absorbing member can have an outer peripheral surface facing outward in a tire radial direction; a plurality of grooves, and a plurality of land portions separated from each other by the plurality of grooves, can be formed in the outer peripheral surface; and each of the plurality of grooves can have an opening width at the outer peripheral surface larger than a groove bottom width of the groove in a cross-section thereof perpendicular to a longitudinal direction of the groove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a pneumatic tire according to one or more embodiments of the present disclosure;

FIG. 2 is a partial perspective view of a sound absorbing member according to one or more embodiments of the present disclosure;

FIG. 3 is an enlarged cross-sectional view perpendicular to a longitudinal direction of a groove of the sound absorbing member of FIG. 2;

FIG. 4 is an enlarged cross-sectional view perpendicular to a longitudinal direction of a groove having chamfered portions formed therein of the sound absorbing member of FIG. 2;

FIG. 5 is a development of the sound absorbing member according to one or more embodiments of the present disclosure, as viewed from above an outer peripheral surface thereof;

FIG. 6 is a partial cross-sectional view of a pneumatic tire according to one or more embodiments of the present disclosure;

FIG. 7 is a schematic diagram showing a material of a sound absorbing member according to one or more embodiments of the present disclosure;

FIG. 8 illustrates manufacturing of a sound absorbing member according to one or more embodiments of the present disclosure; and

FIG. 9 is a development of a sound absorbing member according to another embodiment of the present disclosure, as viewed from above an outer peripheral surface thereof.

DETAILED DESCRIPTION

According to the inventors' study, when repairing a puncture in an area where the sound absorber is adhered to using repair fluid, the loading time required to repair the puncture might be longer because the repair fluid is supplied through the sound absorber.

One or more embodiments of the present disclosure have been made in at least in view of the above circumstances, and an object of one or more embodiments of the present disclosure, among multiple objections, can be to provide a pneumatic tire in which a sponge-like sound absorbing member can be provided on an inner surface of a tread portion and which can achieve one or both improved efficiency of puncture repair with a puncture repair material and noise performance.

As a result of having the configurations according to or based on those described herein, a pneumatic tire according to one or more embodiments of the present disclosure can achieve one or both improved efficiency of puncture repair with a puncture repair material and noise performance.

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

FIG. 1 is a tire meridian cross-sectional view of a pneumatic tire 1 according to one or more embodiments of the present disclosure in a standardized state, including the rotation axis of the pneumatic tire 1. Here, the “standardized state” can be regarded as a state where: the pneumatic tire 1 is fitted on a standardized rim and adjusted to a standardized internal pressure; and no load is applied to the pneumatic tire 1. Hereinafter, unless otherwise specified, dimensions and the like of components of the pneumatic tire 1 can be values measured in the standardized state.

If there is a standard system including a standard on which the pneumatic tire 1 is based, the “standardized rim” can be regarded a rim that is defined for each tire by the standard, and can be, for example, the “standard rim” in the JATMA standard, the “Design Rim” in the TRA standard, or the “Measuring Rim” in the ETRTO standard. If there is no standard system including a standard on which the pneumatic tire 1 is based, the “standardized rim” can be regarded as a rim having the smallest rim diameter and having the smallest rim width, among rims to which the pneumatic tire 1 can be fitted and which do not cause air leakage.

If there is a standard system including a standard on which the pneumatic tire 1 is based, the “standardized internal pressure” can be regarded as an air pressure that is defined for each tire by each standard, and can be the “maximum air pressure” in the JATMA standard, the maximum value indicated in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, or the “INFLATION PRESSURE” in the ETRTO standard. If there is no standard system including a standard on which the pneumatic tire 1 is based, the “standardized internal pressure” can be regarded as an air pressure that is defined for each tire by the manufacturer or the like.

As shown in FIG. 1, the pneumatic tire 1 according to one or more embodiments of the present disclosure can have a tread portion 2 that extends annularly, a pair of sidewall portions 3 provided on both sides in the tire axial direction of the tread portion 2, and bead portions 4 provided inward of the respective sidewall portions 3 in the tire radial direction.

The tread portion 2 according to one or more embodiments of the present disclosure can have an outer surface 2a that forms a ground-contact surface that can be brought into contact with a road surface during running. The sidewall portions 3 can extend inward in the tire radial direction from both sides in the tire axial direction of the tread portion 2. For example, a buttress portion can be provided between the tread portion 2 and each sidewall portion 3. Each bead portion 4 can include, for example, a portion that can be brought into contact with a rim when the tire 1 is fitted onto the rim. The bead portion 4 according to one or more embodiments of the present disclosure can have a bead core 5 that extends annularly. The bead core 5 can be formed of, for example, a steel wire.

The pneumatic tire 1 according to one or more embodiments of the present disclosure can have a carcass 6 that can extend from the tread portion 2 to the pair of bead portions 4 through the pair of sidewall portions 3, and a belt layer 7 that can be provided outward of the carcass 6 in the tire radial direction in the tread portion 2. The pneumatic tire 1 may have, for example, a band layer provided outward of the belt layer 7 in the tire radial direction.

The carcass 6 can extend toroidally between the bead cores 5 of the pair of bead portions 4 through the tread portion 2 and the pair of sidewall portions 3. The carcass 6 can include at least one (e.g., one, two, etc.) carcass ply 6A. The carcass ply 6A according to one or more embodiments of the present disclosure can extend on and between the pair of bead portions 4 through the tread portion 2 and the pair of sidewall portions 3.

The carcass ply 6A can include, for example, a body portion 6a that can extend from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3, and a turned-up portion 6b that can be connected to the body portion 6a and turned up around the bead core 5 from the inside to the outside in the tire axial direction. Such carcass 6 can enhance the stiffness of the bead portion 4 and can serve to improve the durability of the pneumatic tire 1.

The belt layer 7 can include one or more (e.g., one, two, etc.) belt plies 7A and 7B. The two belt plies 7A and 7B can include, for example, a first belt ply 7A located on the inner side in the tire radial direction, and a second belt ply 7B located outward of the first belt ply 7A in the tire radial direction. Such belt layer 7 can enhance the stiffness of the tread portion 2 and can serve to improve the durability of the pneumatic tire 1.

The pneumatic tire 1 can have, for example, bead apexes 8 that can be provided in the bead portions 4 and that can extend outward in the tire radial direction. For example, each bead apex 8 can extend outward in the tire radial direction from the bead core 5, between the body portion 6a and the turned-up portion 6b of the carcass 6. Such bead apex 8 can enhance the stiffness of the bead portion 4 and can serve to improve the durability of the pneumatic tire 1.

The pneumatic tire 1 according to one or more embodiments of the present disclosure can have a sponge-like sound absorbing member 9 on an inner surface 2b in the tire radial direction of the tread portion 2. Put another way, the sound absorbing member 9 can have qualities typically associated with a sponge, for instance, porousness, compression and expansion properties, etc. (in addition to sound absorbing properties). According to one or more embodiments, the sound absorbing member 9 may be regarded or referred to as a sound absorber. The sound absorbing member 9 can have an outer peripheral surface 9a that faces outward in the tire radial direction, and an inner peripheral surface 9b that faces inward in the tire radial direction. The sound absorbing member 9 according to one or more embodiments of the present disclosure can be firmly attached at the outer peripheral surface 9a to the inner surface 2b of the tread portion 2.

Such sound absorbing member 9 can reduce the road noise of the pneumatic tire 1 and can improve the noise performance of the pneumatic tire 1. Here, the sound absorbing member 9 may be firmly attached to the inner surface 2b by a sticky agent, an adhesive agent, a double-sided tape, or the like, or alternatively, may be fixed to the inner surface 2b by a sealant or the like applied to the inner surface 2b.

FIG. 2 is a partial perspective view of the sound absorbing member 9. As shown in FIG. 1 and FIG. 2, a plurality of grooves 10, and a plurality of land portions 11 separated from each other by the plurality of grooves 10, can be formed in the outer peripheral surface 9a of the sound absorbing member 9 of one or more embodiments of the present disclosure. In the present embodiment shown in FIG. 2, the plurality of land portions 11 can be each firmly attached to the inner surface 2b of the tread portion 2 continuously along a longitudinal direction of the groove 10.

When the pneumatic tire 1 has a puncture, such sound absorbing member 9 can allow a puncture repair material to be fed to a puncture area through the groove 10, which can allow reliable repair of the puncture area. In addition, since spaces can be formed between the sound absorbing member 9 and the tread portion 2 by the grooves 10, when heat is generated by the tread portion 2, for instance, during high speed running, heat accumulation by the sound absorbing member 9 can be reduced.

FIG. 3 is an enlarged cross-sectional view perpendicular to the longitudinal direction of the groove 10. As shown in FIG. 2 and FIG. 3, the plurality of grooves 10 of one or more embodiments of the present disclosure can each have an opening width w1 at the outer peripheral surface 9a larger than a groove bottom width w2 of the groove 10 in a cross-section thereof perpendicular to the longitudinal direction of the groove 10.

Such sound absorbing member 9 can reduce the attached area thereof to the inner surface 2b of the tread portion 2, which can make it relatively easy to feed the puncture repair material to a puncture area while maintaining good noise performance of the pneumatic tire 1. Therefore, the pneumatic tire 1 of one or more embodiments of the present disclosure can achieve both improved efficiency of puncture repair with the puncture repair material and noise performance.

According to one or more embodiments of the present disclosure, the attached area of the outer peripheral surface 9a to the inner surface 2b can be 10% to 48% of the projected area of the sound absorbing member 9 onto the inner surface 2b, as an example. As the attached area may be not less than 10% of the projected area, the coming off of the sound absorbing member 9 can be suppressed, which can lead to an improvement in the durability of the pneumatic tire 1. As the attached area may be not greater than 48% of the projected area, the area of the inner surface 2b which is not in contact with the sound absorbing member 9 can be increased, so that efficiency of puncture repair with the puncture repair material can be improved.

Each groove 10 can have, for example, a trapezoidal cross-sectional shape in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. Such groove 10 can suppress a reduction in the volume of the sound absorbing member 9 while having an increased opening width w1 at the outer peripheral surface 9a, so that one or both improved efficiency of puncture repair with the puncture repair material and noise performance can be achieved.

The opening widths w1 of the plurality of grooves 10 of one or more embodiments of the present disclosure can be equal to each other in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. In addition, the groove bottom widths w2 of the plurality of grooves 10 of one or more embodiments of the present disclosure can be equal to each other in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. Such sound absorbing member 9 can reduce non-uniformity in a direction perpendicular to the longitudinal direction, which can improve the noise performance of the pneumatic tire 1 in a well-balanced manner.

Widths w3 at the outer peripheral surface 9a of the plurality of land portions 11 of one or more embodiments of the present disclosure can be equal to each other in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. Optionally, the width w3 of each land portion 11 can be equal to the groove bottom width w2 of each groove 10. Optionally, according to one or more embodiments, widths w4 of the plurality of land portions 11 can be equal to each other in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. The maximum width w4 of each land portion 11 can be equal to the opening width w1 of each groove 10, according to one or more embodiments of the present disclosure.

That is, the cross-sectional shape of each land portion 11 can be the same as the cross-sectional shape of each groove 10. In the case of such sound absorbing member 9, when a single material M (e.g., shown in FIG. 7) is cut along the outer peripheral surface 9a and thereby divided into two portions, both of the two portions can be used as the sound absorbing member 9, which can result in a reduction in manufacturing loss.

The opening width w1 of each groove 10 can be 5 to 50 mm, as an example. As the opening width w1 may be not less than 5 mm, a space can be reliably formed between the groove 10 and the inner surface 2b, so that efficiency of puncture repair of the pneumatic tire 1 with the puncture repair material can be improved. As the opening width w1 may be not greater than 50 mm, a good noise reduction effect of the sound absorbing member 9 can be maintained, so that the noise performance of the pneumatic tire 1 can be improved.

The groove bottom width w2 of each groove 10 can be 3 to 30 mm, as an example. As the groove bottom width w2 may be not less than 3 mm, the cross-sectional area of the groove 10 can be increased, so that efficiency of puncture repair with the puncture repair material can be improved. In addition, in the case where the width w3 of each land portion 11 is equal to the groove bottom width w2, this can serve to maintain the strength of the sound absorbing member 9, so that the durability of the pneumatic tire 1 can be improved. As the groove bottom width w2 may be not greater than 30 mm, a good noise reduction effect of the sound absorbing member 9 can be maintained, so that the noise performance of the pneumatic tire 1 can be improved.

Each groove 10 can have a groove depth d of 1 to 10 mm from the outer peripheral surface 9a, as an example. As the groove depth d may be not less than 1 mm, a space can be reliably formed between the groove 10 and the inner surface 2b, so that efficiency of puncture repair with the puncture repair material can be improved. From such a viewpoint, in the case where the means for firmly attaching the sound absorbing member 9 is a sticky agent or a double-sided tape, the groove depth d can be not less than 2 mm, as an example. In the case where the sound absorbing member 9 is firmly attached by a sealant, the groove depth d can be not less than 3 mm, as an example. As the groove depth d may be not greater than 10 mm, a good noise reduction effect of the sound absorbing member 9 can be maintained, so that the noise performance of the pneumatic tire 1 can be improved.

As shown in FIG. 3, each groove 10 can have a pair of groove walls 10a. Each groove wall 10a can have a wall surface 10b that is inclined with respect to the outer peripheral surface 9a. An inclination angle θ1 between the wall surface 10b and the outer peripheral surface 9a can be 95 to 170°, as an example. Such groove 10 can have an obtuse inclination angle θ1, and thus can reduce a decrease in the strength of the land portion 11 and suppress the coming off of the sound absorbing member 9, so that the durability of the pneumatic tire 1 can be improved.

Each groove 10 can have a bottom surface 10c that connects the pair of wall surfaces 10b. An inclination angle θ2 between the wall surface 10b and the bottom surface 10c can be equal to the inclination angle θ1 between the wall surface 10b and the outer peripheral surface 9a. In such sound absorbing member 9, the outer peripheral surface 9a and the bottom surface 10c can be formed so as to be parallel to each other, so that when the single material M (e.g., shown in FIG. 7) is cut along the outer peripheral surface 9a and thereby divided into two portions, it can be useful to use both of the two portions as the sound absorbing member 9.

FIG. 4 is an enlarged cross-sectional view perpendicular to the longitudinal direction of a groove 10 having chamfered portions 10d formed therein. As shown in FIG. 4, for example, a chamfered portion 10d may be formed at each of corner portions between the wall surfaces 10b and the bottom surface 10c. The chamfered portion 10d can be formed, for example, in an arc shape in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. Such a groove 10 can reduce a decrease in the strength of the land portion 11 and suppress the coming off of the sound absorbing member 9, so that the durability of the pneumatic tire 1 can be improved.

A chamfered portion 12 having an arc shape can be formed at each of corner portions between the wall surfaces 10b and the outer peripheral surface 9a of this embodiment. The chamfered portions 10d on the bottom surface 10c and the chamfered portions 12 on the outer peripheral surface 9a can have the same radius of curvature r, according to one or more embodiments of the present disclosure. Such land portion 11 can maintain good strength and serves to suppress the coming off of the sound absorbing member 9.

The opening width w1 of the groove 10 having the chamfered portions 12 formed therein can be defined as the minimum distance between the chamfered portions 12. In addition, the groove bottom width w2 of the groove 10 having the chamfered portions 10d formed therein can be defined, for example, as the length of a straight portion between the chamfered portions 10d. Similarly, according to one or more embodiments, the width w3 of the land portion 11 having the chamfered portions 12 formed therein can be defined as the length of a straight portion between the chamfered portions 12, and the maximum width w4 of the land portion 11 having the chamfered portions 10d formed therein can be defined as the maximum distance between the chamfered portions 10d.

The radius of curvature r of each of the chamfered portions 10d on the bottom surface 10c and the chamfered portions 12 on the outer peripheral surface 9a can be 0.5 to 2 mm, for instance. As the radius of curvature r is not less than 0.5 mm, the strength of the land portion 11 can be maintained, and therefore, the coming off of the sound absorbing member 9 due to the deformation of the tread portion 2 during running can be suppressed. As the radius of curvature r may be not greater than 2 mm, for instance, a decrease in the attached area of the sound absorbing member 9 can be reduced, which can lead to suppression of the coming off of the sound absorbing member 9.

FIG. 5 is a development of the sound absorbing member 9 according to one or more embodiments of the present disclosure as viewed from above the outer peripheral surface 9a. As shown in FIG. 5, each groove 10 can extend at an angle θ3 of less than 5° with respect to the tire circumferential direction. That is, each groove 10 can be said to extend in parallel to the tire circumferential direction. The sound absorbing member 9 can have, for example, a pair of end surfaces 9c in the tire circumferential direction. Each groove 10 can be open at the pair of end surfaces 9c. Such sound absorbing member 9 can have one or both of a preferable attached area and a preferable strength, and can make the feeding of the puncture repair material more efficient in addition to suppression of the coming off of the sound absorbing member 9, so that both improved efficiency of puncture repair with the puncture repair material and durability of the pneumatic tire 1 can be achieved.

FIG. 6 is a partial cross-sectional view of the pneumatic tire 1 taken at a tire equator C. Here, the tire equator C can be located at the center position between tread ground-contact ends Te on both sides in the tire axial direction shown in FIG. 1. The tread ground-contact ends Te may be regarded as outermost ground-contact positions in the tire axial direction when a standardized load is applied to the pneumatic tire 1 in the standardized state and the tire 1 is brought into contact with a flat surface at a camber angle of 0°. In other words, a tread ground-contact width TW between the tread ground-contact ends Te can be the maximum width of a ground-contact surface when a standardized load is applied to the pneumatic tire 1 in the standardized state.

If there is a standard system including a standard on which the pneumatic tire 1 is based, the “standardized load” can be regarded as a load that is defined for each tire by each standard, and is the “maximum load capacity” in the JATMA standard, the maximum value indicated in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, or the “LOAD CAPACITY” in the ETRTO standard. If there is no standard system including a standard on which the pneumatic tire 1 is based, the “standardized load” can be regarded as a load that is defined for each tire by the manufacturer or the like.

As shown in FIG. 6, for instance, a space L can be formed between the pair of end surfaces 9c of the sound absorbing member 9 firmly attached to the inner surface 2b of the pneumatic tire 1 according to one or more embodiments of the present disclosure. Such sound absorbing member 9 can allow the puncture repair material to be fed from the end surface 9c of the groove 10, so that efficiency of puncture repair with the puncture repair material can be improved.

The space L between the end surfaces 9c can be 3 to 60 mm, as an example. As the space L may be not less than 3 mm, for instance, the puncture repair material can be reliably fed from the end surface 9c of the groove 10. As the space L may be not greater than 60 mm, for instance, non-uniformity in the tire circumferential direction can be reduced, which can lead to suppression of occurrence of vibrations, noise, and the like, for instance, during high speed running.

At least one (e.g., in the present embodiment, both) of the pair of end surfaces 9c can have a tapered surface 9d whose height in the tire radial direction gradually becomes smaller. The tapered surface 9d can be formed in a flat surface shape. The tapered surface 9d may, for example, be formed in an arc shape. The coming off of such sound absorbing member 9 from the end surface 9c, at which stress can be concentrated during running, can be suppressed, which can lead to an improvement in the high speed durability of the pneumatic tire 1.

The tapered surface 9d can be formed in a portion of the end surface 9c. The portion of the end surface 9c in which the tapered surface 9d is not formed can have a height H of 3 to 10 mm, as an example. In such sound absorbing member 9, damage to a sharp portion of the end surface 9c can be reduced, which can lead to an improvement in efficiency of the work of firmly attaching the sound absorbing member 9 to the inner surface 2b of the tread portion 2. It should be noted that the tapered surface 9d may be formed throughout the end surface 9c, for example.

The tapered surface 9d can be inclined at angle θ4 of 30 to 80° with respect to the inner peripheral surface 9b, as an example. As the angle θ4 with respect to the inner peripheral surface 9b may be not less than 30°, the effect of absorbing sound by the sound absorbing member 9 can be maintained at a satisfactory level. As the angle θ4 with respect to the inner peripheral surface 9b may be not greater than 80°, the effect of suppressing the coming off of the sound absorbing member 9 from the end surface 9c can be reliably achieved.

In the pneumatic tire 1, the single sound absorbing member 9 can be firmly attached with the space L formed between the pair of end surfaces 9c in the tire circumferential direction. However, the pneumatic tire 1 according to one or more embodiments of the disclosed subject matter are not limited to such a mode. Alternatively, in the pneumatic tire 1, a plurality of sound absorbing members 9 may be firmly attached with spaces L formed in the tire circumferential direction. In that case, a space L can be formed between the end surfaces 9c of adjacent sound absorbing members 9. For such pneumatic tire 1, the quantity, shape, and the like of the sound absorbing members 9 can be selected, depending on the purpose.

As shown in FIG. 1, a width W1 in the tire axial direction of the sound absorbing member 9 can be smaller than a width Wa in the tire axial direction of the belt layer 7. With such sound absorbing member 9, an excessive increase in the weight of the pneumatic tire 1 can be suppressed, which can lead to an improvement in the handling stability of the pneumatic tire 1.

FIG. 7 is a schematic diagram showing the material M of the sound absorbing member 9, and FIG. 8 illustrates manufacturing of the sound absorbing member 9. As shown in FIG. 7 and FIG. 8, the sound absorbing member 9 according to one or more embodiments of the present disclosure can be manufactured by cutting the single material M along the outer peripheral surface 9a. As for the sound absorbing member 9, for example, the material M can be cut along the grooves 10 and the land portions 11, can then be slid in the longitudinal direction of the groove 10, and thereby can be separated into two sound absorbing members 9.

The sound absorbing member 9 can be asymmetrical in the width direction thereof in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. Therefore, as for the sound absorbing member 9 according to one or more embodiments of the disclosed subject matter, the separated two sound absorbing members 9 can be used as sound absorbing members 9 having the same shape, which can result in a further reduction in manufacturing loss.

A sponge material can suitably used as the material M of the sound absorbing member 9. Examples of the sponge material include ether-based polyurethane, ester-based polyurethane, and polyethylene. Such sound absorbing member 9 can reduce road noise while suppressing weight increase. The sponge material according to one or more embodiments of the disclosed subject matter, however, is not limited to such a mode, and may be, for example, a rubber-based sponge material.

FIG. 9 is a development of a sound absorbing member 19 according to another embodiment as viewed from above an outer peripheral surface 19a thereof. As shown in FIG. 9, a plurality of grooves 10, and a plurality of land portions 11 separated from each other by the plurality of grooves 10, can be formed in the outer peripheral surface 19a of the sound absorbing member 19, as in the above-described sound absorbing member 9. In the present embodiment as well, the plurality of land portions 11 can each be firmly attached to the inner surface 2b of the tread portion 2 (e.g., as shown in FIG. 1) continuously along a longitudinal direction of the groove 10.

Each groove 10 of the present embodiment can extend at an angle θ5 of 5 to 90° with respect to the tire circumferential direction, as an example. In the case where the angle θ5 of the groove 10 is, for example, about 15 to 45°, the groove 10 can effectively contribute to high speed durability. In the case where the angle θ5 of the groove 10 is close to 90° (e.g., plus or minus three degrees), the groove 10 can effectively contribute to feeding of the puncture repair material. Therefore, the angle θ5 of the groove 10 can be 45 to 60°, according to one or more embodiments of the present disclosure. Such a sound absorbing member 19 can serve to achieve both high speed durability and efficiency of puncture repair.

Although particular embodiments have been described in detail above, one or more embodiments of the present disclosure are not limited to the above-described embodiments, and various modifications can be made to implement one or more embodiments of the present disclosure.

EXAMPLES

Pneumatic tires having the basic structure in FIG. 1 were produced as test tires based on specifications in Table 1 and Table 2. Noise performance, puncture repair time, and durability were evaluated using the produced test tires. Select common specifications and evaluation methods are as follows.

Common Specifications

Tire size: 215/55R17

Width W1 of sound absorbing member: 120 mm

Material M of sound absorbing member: ether-based polyurethane

Noise Performance

A test tire having an air pressure adjusted to 250 kPa was mounted to a drum tester installed in an anechoic room, and the sound pressure was measured when running at 120 km/h in a state where a load of 6.6 kN was applied to the tire, and was evaluated as an index whose value was higher as a cavity resonance sound peak value was lower. The results are represented as indexes with the result of Comparative Example 1 being regarded as 100. A higher value indicates that the cavity resonance sound peak value is lower and the noise performance is better.

Puncture Repair Time

A test tire was punctured by penetrating a 5-mm-diameter nail through a center area of the tread portion of the test tire, and the puncture was repaired with a puncture repair material using a commercially available puncture repair kit. The time taken for the puncture repair material to stop flowing out from the puncture area was measured, and was evaluated as an index whose value was higher as the time was shorter. The results are represented as indexes with the result of Comparative Example 1 being regarded as 100. A higher value indicates that the time taken for the puncture repair material to stop flowing out is shorter and the puncture repair is performed more efficiently.

Durability

A test tire having an air pressure adjusted to 250 kPa was mounted to a drum tester, and the state of the internal structure of the tire was evaluated after running for 30000 km at 120 km/h in a state where a load of 6.6 kN was applied to the tire. The results are represented as indexes with the result of Comparative Example 1 being regarded as 100. A higher value indicates that the state of the internal structure of the tire is better and the durability is better. The results of the evaluation are shown in Table 1 and Table 2.

TABLE 1

Comp.
Comp.

Ex. 1
Ex. 2
Ex. 1
Ex. 2
Ex. 3
Ex. 4
Ex. 5
Ex. 6
Ex. 7

Height of sound absorbing
22.5
25
25
25
25
25
25
25
25

member (mm)

Attached area/projected area (%)
100
50
37
11
48
32
47
45
23

Opening width w1 of groove (mm)
—
5.0
8.5
39.0
5.5
6.5
30.0
6.2
16.5

Groove bottom width w2 of
—
5.0
5.0
5.0
5.0
3.0
33.0
5.0
5.0

groove (mm)

Groove depth d of groove (mm)
—
3
3
3
3
3
3
1
10

Radius of curvature r of chamfered
—
0
0
0
0
0
0
0
0

portion (mm)

Inclination angle θ1 between wall
—
90
120
170
95
120
120
120
120

surface and outer peripheral

surface (°)

Angles θ3 and θ5 of groove (°)
—
0
0
0
0
0
0
0
0

Angle θ4 of tapered surface (°)
90
90
90
90
90
90
90
90
90

Space L of sound absorbing
0
0
0
0
0
0
0
0
0

member (mm)

Noise performance (index)
100
95
100
100
100
100
100
100
100

Puncture repair time (index)
100
110
120
130
110
110
130
110
130

Durability (index)
100
110
120
120
110
120
110
110
120

TABLE 2

Ex. 8
Ex. 9
Ex. 10
Ex. 11
Ex. 12
Ex. 13
Ex. 14
Ex. 15
Ex. 16
Ex. 17

Height of sound absorbing
25
25
25
25
25
25
25
25
25
25

member (mm)

Attached area/projected area
37
37
37
37
37
37
37
37
37
37

(%)

Opening width w1 of groove
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5

(mm)

Groove bottom width w2 of
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0

groove (mm)

Groove depth d of groove
3
3
3
3
3
3
3
3
3
3

(mm)

Radius of curvature r of
0.5
2.0
0
0
0
0
0
0
0
0

chamfered portion (mm)

Inclination angle θ1 between
120
120
120
120
120
120
120
120
120
120

wall surface and outer

peripheral surface (°)

Angles θ3 and θ5 of groove (°)
0
0
30
45
60
90
0
0
0
0

Angle θ4 of tapered surface (°)
90
90
90
90
90
90
30
80
90
90

Space L of sound absorbing
0
0
0
0
0
0
0
0
3
60

member (mm)

Noise performance (index)
100
100
100
100
100
100
95
100
100
100

Puncture repair time (index)
120
120
120
120
120
120
120
120
130
140

As a result of the evaluation, it is confirmed that the pneumatic tire of each Example has a shorter puncture repair time while maintaining the same noise performance, as compared to that of each Comparative Example, and achieves both improved efficiency of puncture repair with the puncture repair material and noise performance. In addition, it is confirmed that the pneumatic tire of each Example has better durability as compared to that of each Comparative Example.

Additional Note

Embodiments of the disclosed subject matter can also be as set forth according to the following brackets.

[1]

A pneumatic tire including a tread portion, wherein

a sponge-like sound absorbing member is firmly attached to an inner surface of the tread portion,

the sound absorbing member has an outer peripheral surface facing outward in a tire radial direction,

a plurality of grooves, and a plurality of land portions separated from each other by the plurality of grooves, are formed in the outer peripheral surface, and

each of the plurality of grooves has an opening width at the outer peripheral surface larger than a groove bottom width of the groove in a cross-section thereof perpendicular to a longitudinal direction of the groove.

[2]

The pneumatic tire according to [1], wherein an attached area of the outer peripheral surface to the inner surface is 10% to 48% of a projected area of the sound absorbing member onto the inner surface.

[3]

The pneumatic tire according to [1] or [2], wherein each of the plurality of grooves has a trapezoidal cross-sectional shape in the cross-section.

[4]

The pneumatic tire according to any one of [1] to [3], wherein

each of the plurality of grooves has a pair of groove walls,

each of the pair of groove walls has a wall surface inclined with respect to the outer peripheral surface, and

an inclination angle between the wall surface and the outer peripheral surface is 95 to 170°.

[5]

The pneumatic tire according to any one of [1] to [4], wherein a chamfered portion is formed at each of corner portions between the wall surfaces and the outer peripheral surface.

[6]

The pneumatic tire according to any one of [1] to [5], wherein

the groove bottom widths of the plurality of grooves are equal to each other in the cross-section,

widths at the outer peripheral surface of the plurality of land portions are equal to each other in the cross-section, and

each of the widths is equal to the groove bottom width.

[7]

The pneumatic tire according to any one of [1] to [6], wherein

the groove bottom width of each of the plurality of grooves is 3 to 30 mm, and

each of the grooves has a groove depth of 1 to 10 mm.

[8]

The pneumatic tire according to any one of [1] to [7], wherein each of the plurality of grooves extends at an angle of 5 to 90° with respect to a tire circumferential direction.

[9]

The pneumatic tire according to any one of [1] to [8], wherein each of the plurality of grooves extends at an angle of less than 5° with respect to a tire circumferential direction.

[10]

The pneumatic tire according to any one of [1] to [9], wherein

the sound absorbing member has a pair of end surfaces in the tire circumferential direction, and

a space is formed between the pair of end surfaces.

[11]

A pneumatic tire comprising:

a tread portion; and

a sound absorber on an inner surface of the tread portion,

wherein the sound absorber defines an outer peripheral surface facing outward in a tire radial direction and an inner peripheral surface facing inward in the tire radial direction,

wherein the sound absorber includes:

- a plurality of grooves, which extend from a first side of the sound absorber to a second side of the sound absorber, on the outer peripheral surface, and
- a plurality of land portions, which extend from the first side of the sound absorber to the second side of the sound absorber, on the outer peripheral surface, the plurality of land portions being separated from each other by respective ones of the plurality of grooves,

wherein each of the plurality of land portions is fixedly attached to the inner surface of the tread portion continuously along a longitudinal direction of the plurality of grooves,

wherein a maximum thickness of the sound absorber is less than a maximum depth of the plurality of grooves,

wherein each of the plurality of grooves has a trapezoidal cross-sectional shape in cross-section, and

wherein the sound absorber is asymmetrical in a width direction thereof in the cross section.

[12]

The pneumatic tire according to [11], wherein the first side of the sound absorber is a first end of the sound absorber, and the second side of the sound absorber is a second end of the sound absorber opposite the first end in the longitudinal direction of the plurality of grooves.

[13]

The pneumatic tire according to or [12], wherein a first width of at least some of the plurality of grooves is the same as a second width of at least some of the plurality of land portions.

[14]

The pneumatic tire according to any one of to [13], wherein no portion of each of the plurality of grooves is directly fixedly attached to the inner surface of the tread portion.

[15]

The pneumatic tire according to any one of to [14],

wherein a cross-section of each of the plurality of grooves is the same, and

wherein the grooves are open at each of the first side of the sound absorber and the second side of the sound absorber.

[16]

The pneumatic tire according to any one of to [15],

wherein a width in a tire axial direction of the sound absorber is smaller than a width in the tire axial direction of a belt layer of the pneumatic tire.

Number	Date	Country	Kind
2022-121202	Jul 2022	JP	national
2022-179835	Nov 2022	JP	national

PNEUMATIC TIRE

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Priority Claims (2)