Patent Application
20240034103
The present application claims priority to Japanese patent application JP 2022-121202, filed on Jul. 29, 2022, the entire contents of which is incorporated herein by reference in its entirety.
The present disclosure relates to a pneumatic tire having a tread portion.
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.
According an aspect of the present disclosure, a pneumatic tire can include a tread portion wherein: a sponge-like sound absorbing member on 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 land portions can be attached to the inner surface continuously along a longitudinal direction of the groove.
According to the inventors' study, heat generated by the tread of pneumatic tires at high speeds may cause a sound absorber to store heat and affect the tread.
Embodiments of the present disclosure have been made in view of the above circumstances, and an object of one or more embodiments of the present disclosure, among multiple objects, can be to provide a pneumatic tire in which a sponge-like sound absorbing member is provided on an inner surface of a tread portion and which can have improved high speed durability.
As a result of having configurations as described herein, the pneumatic tire according to one or more embodiments of the present disclosure can have improved high speed durability.
Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.
If there is a standard system including a standard on which the pneumatic tire 1 is based, the “standardized rim” can be regarded as a rim that is defined for each tire by the standard, and is, 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 is 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
The tread portion 2 of one or more embodiments of the present disclosure can have an outer surface 2a that forms a ground-contact surface that is 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 is brought into contact with a rim when the tire 1 is fitted onto the rim. The bead portion 4 of one or more embodiments of the present disclosure can have a bead core 5 that extends annularly. The bead core 5 may be formed of, for example, a steel wire.
The pneumatic tire 1 of one or more embodiments of the present disclosure can have a carcass 6 that extends from the tread portion 2 to the pair of bead portions 4 through the pair of sidewall portions 3, and a belt layer 7 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 that is 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, or two, or more) carcass ply 6A. The carcass ply 6A of 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 extends 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 a 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, or more) 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 a 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 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 a 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 of one or more embodiments of the present 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). 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 of one or more embodiments of the present embodiment can be firmly attached at the outer peripheral surface 9a to the inner surface 2b of the tread portion 2. 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.
Such sound absorbing member 9 can reduce the road noise 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.
Spaces can be formed between such sound absorbing member 9 and the tread portion 2 by the grooves 10. Therefore, 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. Therefore, the pneumatic tire 1 according to one or more embodiments of the present disclosure can have improved high speed durability. In addition, when the pneumatic tire 1 has a puncture, the sound absorbing member 9 can allow a puncture repair material to be fed to a puncture area through the groove 10, resulting in efficient puncture repair.
According to one or more embodiments, the attached area of the plurality of land portions 11 to the inner surface 2b can be 25% to 50% of the projected area of the sound absorbing member 9 onto the inner surface 2b, for instance, such as from 27.5% to 47.5% or from 30% to 45%. As the attached area may be not less than 25% of the projected area, then even when the tread portion 2 becomes deformed (e.g., significantly deformed), for instance, during high speed running, the coming off of the sound absorbing member 9 can be suppressed, which can lead to an improvement in the high speed durability of the pneumatic tire 1. As the attached area may be not greater than 50% of the projected area, the heat accumulation of the sound absorbing member 9, for instance, during high speed running, can be reliably reduced, which can lead to an improvement in the high speed durability of the pneumatic tire 1.
The plurality of land portions 11 can be firmly attached to the inner surface 2b of the tread portion 2 over widths w2 which are equal to each other, in a cross-section thereof perpendicular to the longitudinal direction of the groove 10 (as shown in
The groove width w1 of each groove 10 can be 3 to 10 mm at the outer peripheral surface 9a, as an example. As the groove width w1 may be not less than 3 mm, a space can be reliably formed between the groove 10 and the inner surface 2b. Therefore, heat accumulation can be reduced, and efficiency of puncture repair can be improved. As the groove width w1 may be not greater than 10 mm, a force applied to each land portion 11 can be reduced during running, and therefore, the coming off of the sound absorbing member 9 can be suppressed.
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, and therefore, heat accumulation can be reduced, and efficiency of puncture repair 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 decrease in the strength of the land portions 11 due to the formation of the grooves 10 can be reduced, and therefore, the coming off of the sound absorbing member 9 can be suppressed.
As shown in
Each groove 10 can have a bottom surface 10c that connects the pair of wall surfaces 10b. A chamfered portion 10d can be formed at each of corner portions between the wall surfaces 10b and the bottom surface 10c according to one or more embodiments of the present disclosure. 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 can serve to suppress the coming off of the sound absorbing member 9.
A chamfered portion 12 can be formed at each of corner portions between the wall surfaces 10b and the outer peripheral surface 9a according to one or more embodiments of the present disclosure. The chamfered portion 12 can be formed, for example, in an arc shape in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. 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 a land portion 11 can maintain good strength and serve to suppress the coming off of the sound absorbing member 9.
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, as an example. As the radius of curvature r may be 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, 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.
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
The space L between the end surfaces 9c can be 3 to 60 mm, for instance. As the space L may be not less than 3 mm, the puncture repair material can be reliably fed from the end surface 9c of the groove 10. Additionally or alternatively, as the space L may be not greater than 60 mm, non-uniformity in the tire circumferential direction can be reduced, leading to suppression of occurrence of vibrations, noise, and the like 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 may gradually become smaller. The tapered surface 9d can be formed in a flat surface shape, according to one or more embodiments of the present disclosure. 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 may 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 α of 30 to 80° with respect to the inner peripheral surface 9b, as an example. As the angle α 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 α 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 according to one or more embodiments of the present disclosure, 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. The pneumatic tire 1 according to one or more embodiments of the present disclosure, however, may not be limited to such a mode. Alternatively, in the pneumatic tire 1 according to one or more embodiments of the present disclosure, 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
Each groove 10 of the present embodiment can extends at an angle θ of 1 to 90° with respect to the tire circumferential direction, as an example. In the case where the angle θ 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 θ of the groove 10 is close to 900 (e.g. plus or minus three degrees), the groove 10 can effectively contribute to feeding of the puncture repair material. Therefore, the angle θ of the groove 10 may be 45 to 60°, according to one or more embodiments of the present disclosure. Such sound absorbing member 19 can serve to achieve both high speed durability and efficiency of puncture repair.
The sound absorbing member 29 of the present embodiment can have a protrusion-and-recess structure 30 formed in an inner peripheral surface 29b thereof. The protrusion-and-recess structure 30 can include, for example, recesses 30a and protrusions 30b. The protrusion-and-recess structure 30 can be formed independently of the shape of the grooves 10 in the outer peripheral surface 29a. The protrusion-and-recess structure 30 may not be limited to the illustrated form, and may have any shape. The inner peripheral surface 29b of such a sound absorbing member 29 can have a shape advantageous to a reduction in road noise, which can result in a further improvement in noise performance.
Each groove 40 of the present embodiment can have a pair of groove walls 40a. Each groove wall 40a of the present embodiment can have a wall surface 40b inclined with respect to the outer peripheral surface 39a. Such groove 40 can enhance the strength of the land portion 41, which can be effective in the case where the sound absorbing member 39 may have a smaller attached area.
The sound absorbing member 49 of the present embodiment can be asymmetric in a width direction in a cross-section thereof perpendicular to the longitudinal direction of the groove 10. In the case of the sound absorbing member 49, when a single material is cut along the outer peripheral surface 49a and thereby divided into two portions, both of the two portions can be used as the sound absorbing members 49 having the same shape, which can result in a further reduction in manufacturing loss.
Although the particular embodiments have been described in detail above, embodiments of the present disclosure are not limited to the above-described embodiments, and various modifications can be made to implement various embodiments of the present disclosure.
[Additional Note]
Embodiments of the disclosed subject matter can also be as set forth according to the following brackets.
A pneumatic tire including a tread portion, wherein
The pneumatic tire according to [1], wherein an attached area of the plurality of land portions to the inner surface is 25% to 50% of a projected area of the sound absorbing member onto the inner surface.
The pneumatic tire according to [1] or [2], wherein the plurality of grooves have cross-sectional shapes that are the same as each other, in a cross-section thereof perpendicular to the longitudinal direction of the groove.
The pneumatic tire according to any one of [1] to [3], wherein
The pneumatic tire according to any one of [1] to [4], wherein
The pneumatic tire according to any one of [1] to [5], wherein a chamfered portion is formed at each of corner portions between the wall surfaces and the outer peripheral surface.
The pneumatic tire according to any one of [1] to [6], wherein each of the plurality of grooves has a groove width of 3 to 10 mm at the outer peripheral surface and a groove depth of 1 to 10 mm.
The pneumatic tire according to any one of [1] to [7], wherein each of the plurality of grooves extends at an angle of 1 to 90° with respect to a tire circumferential direction.
The pneumatic tire according to any one of [1] to [8], wherein each of the plurality of grooves extends in parallel to a tire circumferential direction.
The pneumatic tire according to any one of [1] to [9], wherein
The pneumatic tire according to any one of [1] to [10], wherein at least one of the pair of end surfaces has a tapered surface whose height in the tire radial direction gradually becomes smaller.
A pneumatic tire comprising:
The pneumatic tire according to [12], 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.
The pneumatic tire according to [12] or [13], 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.
The pneumatic tire according to any one of [12] to [14], wherein no portion of each of the plurality of grooves is directly fixedly attached to the inner surface of the tread portion.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-121202 | Jul 2022 | JP | national |
