tire

Abstract

To provide a tire of which brake performance is improved while noise performance is maintained.SOLUTION: A tire includes a tread part 2 of which a rotation direction R is specified. The tread part 2 includes a first tread end T1, a first inclined groove 5, and a first land part 7. Each of a plurality of first inclined grooves 5 includes a first groove wall 11 on a former landing side in the rotation direction R, and a second groove wall 12 on a later landing side in the rotation direction R. A first chamfered part 13 is formed on the first groove wall 11. A second chamfered part 14 is formed on the second groove wall 12. A chamfered area S1 of the first chamfered part 13 is larger than a chamfered area S2 of the second chamfered part 14 in a cross section orthogonal to a groove center line of the first inclined groove 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a tire.

Background Art

[0002] In Patent Document 1 below, a tire is proposed in which a plurality of inclined grooves extending obliquely from a first tread end on one side in the tire axial direction to the tire equator side are provided in the tread portion.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For a tire provided with inclined grooves as in Patent Document 1 above, further improvement in braking performance has been demanded. On the other hand, in recent years, vehicle quietness has been remarkable, and it has been required to maintain the noise performance of the tire. [[ID=3�]]

[0005] The present disclosure has been devised in view of the above actual situation, and the main object is to provide a tire that improves braking performance while maintaining noise performance.

Means for Solving the Problems

[0006] This disclosure relates to a tire having a tread portion with a specified direction of rotation, wherein the tread portion includes a first tread end, a plurality of first inclined grooves extending at least from the first tread end toward the tire equator toward the leading side in the direction of rotation, and a plurality of first land portions divided into the plurality of first inclined grooves, each of the plurality of first inclined grooves includes a first groove wall toward the leading side in the direction of rotation and a second groove wall toward the trailing side in the direction of rotation, the first groove wall has a first chamfered portion formed thereon, and the second groove wall has a second chamfered portion formed thereon, and in a cross-section perpendicular to the groove centerline of the first inclined groove, the chamfered area S1 of the first chamfered portion is larger than the chamfered area S2 of the second chamfered portion. [Effects of the Invention]

[0007] By adopting the above configuration, the tire disclosed herein can improve braking performance while maintaining noise performance. [Brief explanation of the drawing]

[0008] [Figure 1] This is an exploded view of the tread portion of a tire according to one embodiment of the present disclosure. [Figure 2] This is an enlarged view of the first inclined trench and the first land area in Figure 1. [Figure 3] This is a cross-sectional view along line AA in Figure 2. [Figure 4] Figure 3 shows enlarged views of the first and second chamfered sections. [Figure 5] This is an enlarged cross-sectional view showing the state of a conventional inclined groove when it is in contact with the ground. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings. Figure 1 is an exploded view of the tread portion 2 of the tire (hereinafter sometimes simply referred to as "tire") 1 of this embodiment. As shown in Figure 1, the tire 1 of this embodiment is preferably, for example, a passenger car tire. However, the tire 1 of this disclosure is not limited to this form, and may be, for example, a heavy load tire.

[0010] The tire 1 of this disclosure has a tread portion 2 in which a rotation direction R is specified. The rotation direction R is indicated, for example, on the sidewall portion (not shown) by letters or symbols.

[0011] The tread portion 2 of the tire 1 in this embodiment includes a first tread end T1 and a second tread end T2. In the figures of this specification, the tread end on the left side of the tire equator C is the first tread end T1, and the tread end on the right side of the tire equator C is the second tread end T2. The tread portion 2 includes a first tread portion 2A located on the first tread end T1 side of the tire equator C, and a second tread portion 2B located on the second tread end T2 side of the tire equator C. The first tread portion 2A and the second tread portion 2B are substantially symmetrical with respect to the tire equator C, except for the point of displacement in the circumferential direction of the tire. Therefore, each component of the first tread portion 2A can be applied to the second tread portion 2B.

[0012] The first tread edge T1 and the second tread edge T2 are the outermost contact points in the axial direction of the tire when tire 1 in its normal state is loaded with 60% of its normal load and makes contact with a flat surface at a camber angle of 0°.

[0013] "Normal condition" refers to the state in the case of pneumatic tires for which various standards are defined, where the tire is mounted on a normal rim, filled to the normal internal pressure, and under no load. For tires for which various standards are not defined, or for non-pneumatic tires, the normal condition refers to the standard operating condition according to the intended use of the tire, and is under no load. Unless otherwise specified in this specification, the dimensions of each part of the tire are values ​​measured under normal condition. Furthermore, unless otherwise specified in this specification, known methods may be appropriately applied to the measurement methods of the aforementioned dimensions and material composition.

[0014] A "standard rim" is the rim specified for each tire within the standard system that the tire is based on. For example, it is the "standard rim" for JATMA, the "Design Rim" for TRA, and the "Measuring Rim" for ETRTO.

[0015] "Regular internal pressure" refers to the air pressure specified for each tire by each standard within the tire standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0016] "Regular load" refers to the load specified for each tire within the standard system, including the standard on which the tire is based, in the case of pneumatic tires for which various standards are defined. For example, it is the "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. For tires for which various standards are not defined, "regular load" refers to the maximum load that can be applied when using the tire, in accordance with the above standards.

[0017] The tread portion 2 includes a plurality of first inclined grooves 5 and a plurality of first land portions 7. The first inclined grooves 5 extend at least from the first tread end T1 toward the tire equator C, inclined toward the leading side (downward in each figure herein). In this embodiment, the first inclined grooves 5 are interrupted before reaching the tire equator C. The first inclined grooves 5 may, for example, cross the tire equator C. The first land portion 7 is divided into the first inclined grooves 5.

[0018] The tread portion 2 of the present embodiment includes a plurality of second inclined grooves 6 and a plurality of second land portions 8. The second inclined grooves 6 are inclined and extend at least from the second tread end T2 toward the tire equator C side in the leading side direction. The second land portions 8 are partitioned by the second inclined grooves 6. The second inclined grooves 6 have substantially the same configuration as the first inclined grooves 5, and the configuration of the first inclined grooves 5 can be applied to the second inclined grooves 6. Also, the second land portions 8 have substantially the same configuration as the first land portions 7, and the configuration of the first land portions 7 can be applied to the second land portions 8.

[0019] The groove widths of the first inclined grooves 5 and the second inclined grooves 6 are, for example, 2 to 12 mm. In a preferred embodiment, the groove widths of the first inclined grooves 5 and the second inclined grooves 6 decrease from the first tread end T1 side or the second tread end T2 side toward the tire equator C side. Also, the depths of the first inclined grooves 5 and the second inclined grooves 6 are, for example, 5 to 15 mm. However, the dimensions of each part of the first inclined grooves 5 and the second inclined grooves 6 are not limited to such ranges.

[0020] FIG. 2 shows an enlarged view of two first inclined grooves 5 and one first land portion 7. FIG. 3 shows a cross-sectional view of the first inclined groove 5, which is a cross-sectional view taken along line A-A of FIG. 2. As shown in FIGS. 2 and 3, in the present disclosure, each of the plurality of first inclined grooves 5 includes a first groove wall 11 on the leading side R1 of the rotation direction R and a second groove wall 12 on the trailing side R2 of the rotation direction R. Also, a first chamfer portion 13 is formed on the first groove wall 11, and a second chamfer portion 14 is formed on the second groove wall 12. In FIG. 1, the first chamfer portion 13 and the second chamfer portion 14 are omitted, and in FIG. 2, for easy understanding, the first chamfer portion 13 and the second chamfer portion 14 are conceptually shown by dots.

[0021] Fig. 4 shows an enlarged view of the first chamfered portion 13 and the second chamfered portion 14. In Fig. 4, dots are applied to the cross-sections of the first chamfered portion 13 and the second chamfered portion 14. As shown in Fig. 4, in the cross-section orthogonal to the groove center line of the first inclined groove 5, the chamfered area S1 of the first chamfered portion 13 is larger than the chamfered area S2 of the second chamfered portion 14. By adopting the above configuration, the tire 1 of the present disclosure can improve the braking performance while maintaining the noise performance. The mechanism is as follows.

[0022] Fig. 5 shows an enlarged cross-sectional view of a state where a conventional inclined groove a without a chamfered portion contacts the road surface G. Fig. 5 shows a state during braking, where the arrow R indicates the rotational direction of the tire and the arrow A indicates the traveling direction of the tire. As shown in Fig. 5, generally, when a large braking force acts on the inclined groove a without a chamfered portion, the edge b on the leading side of the inclined groove a (synonymous with the trailing side end of the tread of the land portion) is drawn under the tread of the land portion, and the surface c of the land portion in the vicinity locally lifts off the road surface, and sufficient grip may not be exhibited.

[0023] As shown in Fig. 4, in the present disclosure, since the first chamfered portion 13 is formed on the first groove wall 11, the above-mentioned problem is suppressed and the braking performance is improved. Since the second chamfered portion 14 is formed on the second groove wall 12 of the tire 1 of the present disclosure, an improvement in traction performance can also be expected for the same reason.

[0024] On the other hand, conventionally, when a chamfered portion is provided in the groove, an increase in the groove volume may occur and the noise performance may be impaired. However, in the present disclosure, since the chamfered area S2 of the second chamfered portion 14 is relatively small, it is possible to suppress an excessive increase in the groove volume while obtaining the effect of improving the braking performance, and to maintain the noise performance. The tire 1 of the present disclosure can improve the braking performance while maintaining the noise performance by such a mechanism.

[0025] As shown in Figure 4, the first chamfered portion 13 and the second chamfered portion 14 (hereinafter sometimes simply referred to as "chamfered portion") include a flat or curved surface (hereinafter sometimes collectively referred to as "inclined surface") that is inclined to connect the main body of the groove wall and the tread surface 7s of the first inclined groove 5, so that no sharp corners are formed between the groove wall and the tread surface 7s of the first land portion 7.

[0026] Furthermore, the chamfered area S1 of the first chamfered portion 13 is defined as follows: The chamfered area S1 refers to the area of ​​the region enclosed by the inclined surface 13a of the first chamfered portion 13, the virtual tread surface 7v obtained by extending the tread surface 7s of the first land portion 7 in the groove width direction of the first inclined groove 5, and the first virtual groove wall 11v obtained by extending the main body 11a of the first groove wall 11 to the virtual tread surface 7v.

[0027] The inclined surface 13a of the first chamfered portion 13 refers to the surface from the main body 11a of the first groove wall 11 to the tread surface 7s of the first land portion 7. When 60% of the normal load is applied to the tire 1 in the normal state and it makes contact with a plane at a camber angle of 0°, the edge of the outer surface of the first land portion 7 that contacts the plane becomes the boundary 21 between the inclined surface 13a and the tread surface 7s. The virtual tread surface 7v is a virtual surface that extends from the boundary 21 to the tread surface 7s in the groove width direction, and if the tread surface is curved, the virtual tread surface 7v corresponds to a curve that extends from the boundary 21 to the tread surface 7s in the cross section of the first inclined groove 5 while maintaining the curvature of the tread surface 7s.

[0028] The first virtual groove wall 11v is a virtual surface that extends from the boundary 22 between the main body 11a and the inclined surface 13a of the first groove wall 11 to the virtual tread surface 7v. The boundary 22 between the main body 11a and the inclined surface 13a of the first groove wall 11 is the position where the angle of the first groove wall 11 with respect to the tire radius direction changes abruptly. If the position where the angle changes abruptly is a region with a substantial width, the position closest to the groove centerline within that region corresponds to the boundary 22.

[0029] Furthermore, it goes without saying that the chamfering area S2 of the second chamfered portion 14 is defined in the same way as the chamfering area S1 of the first chamfered portion 13.

[0030] The configuration of this embodiment will be described in more detail below. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that this disclosure can achieve the above-described effects even without the configurations described below. Furthermore, even if any one of the configurations described below is applied individually to a tire of this disclosure having the above-described features, an improvement in performance corresponding to each configuration can be expected. Moreover, if several of the configurations described below are applied in combination, a combined improvement in performance corresponding to each configuration can be expected.

[0031] As shown in Figure 2, it is desirable that the angle of the first inclined groove 5 with respect to the tire circumferential direction increases toward the outward direction in the tire axial direction. In the desired embodiment, the angle increases continuously toward the outward direction in the tire axial direction. As a result, the first inclined groove 5 extends in a curved manner. Specifically, it is desirable that the angle θ1 of the first inclined groove 5 with respect to the tire circumferential direction at the first tread edge T1 be 80 to 90°. Furthermore, the angle θ2 of the first inclined groove 5 with respect to the tire circumferential direction at the inner end 5i on the tire equator C side of the first inclined groove 5 is, for example, 5° or more, and preferably 30 to 70°. This improves braking performance and cornering performance in a well-balanced manner.

[0032] The distance L1 in the axial direction of the tire from the inner end 5i of the first inclined groove 5 on the tire equator C side to the tire equator C is, for example, 10% or less of the tread width TW (shown in Figure 1), and preferably 5% or less. The tread width TW corresponds to the distance in the axial direction of the tire from the first tread end T1 to the second tread end T2 in the normal state. Furthermore, the first inclined groove 5 extends beyond the first tread end T1. This provides excellent wet performance.

[0033] In this disclosure, the above-mentioned effects can be expected to some extent if the first chamfered portion 13 and the second chamfered portion 14 are arranged in a part of the first inclined groove 5. However, from the viewpoint of more reliably achieving the above-mentioned effects, it is desirable that the first chamfered portion 13 and the second chamfered portion 14 are arranged in an area of ​​50% or more of the total length of the first inclined groove 5 (the total length in the region between the tire equator C and the first tread edge T1). In a more desirable embodiment, the first chamfered portion 13 and the second chamfered portion 14 of this embodiment are arranged in the entire first inclined groove 5 in the region between the tire equator C and the first tread edge T1.

[0034] From a similar viewpoint, it is desirable that the chamfered area S1 is larger than the chamfered area S2 in a region of 50% or more of the total length of the first inclined groove 5. In a more desirable embodiment, in this embodiment, the chamfered area S1 is larger than the chamfered area S2 over the entire first inclined groove 5.

[0035] As shown in Figure 4, in this embodiment, the tread surface 7s of the first land portion 7, the groove wall of the first inclined groove 5, and the inclined surface of the chamfered portion are each substantially planar, and the cross-sectional view of the first inclined groove 5 is linear. As a result, the first chamfered portion 13 and the second chamfered portion 14 are configured, for example, in an obtuse triangular shape in cross-sectional view, and in a desirable embodiment, these cross-sectional shapes are similar.

[0036] The chamfer area S1 and the chamfer area S2 are each 0.5 mm. 2 The above is considered appropriate, preferably 0.5-2.0 mm. 2 However, the chamfer area S1 and chamfer area S2 are not limited to these ranges.

[0037] The chamfer area S1 is preferably 1.1 times or more, more preferably 1.2 times or more, preferably 1.5 times or less, and more preferably 1.4 times or less than the chamfer area S2. This improves noise performance and braking performance in a well-balanced manner. Note that in Figures 3 and 4, the difference between the chamfer area S1 and the chamfer area S2 is shown to be larger than it actually is in order to make the technical matters of this disclosure easier to understand.

[0038] It is desirable that the chamfered area S1 of the first chamfered portion 13 increases toward the outward direction in the tire axial direction. In this embodiment, the chamfered area S1 of the first chamfered portion 13 increases continuously from the inner end 5i of the first inclined groove 5 to the first tread end. As a result, the chamfered area S1 becomes smaller on the tire equator C side, which has little contribution to braking performance, and noise performance can be effectively maintained.

[0039] From a similar viewpoint, it is desirable that the chamfered area S2 of the second chamfered portion 14 increases toward the outward direction in the tire axial direction. In this embodiment, the chamfered area S2 of the second chamfered portion 14 increases continuously from the inner end 5i of the first inclined groove 5 to the first tread end T1. This further ensures that the above-mentioned effects are achieved.

[0040] As shown in Figure 2, the first tread section 7 has no grooves or sipes in the region between the tire equator C and the first tread edge T1, and is composed of a smooth tread surface. Such a first tread section 7 can exhibit excellent traction and braking performance.

[0041] Further outward from the first tread edge T1 in the tire axial direction, the first land portion 7 is provided with a narrow transverse groove 25 extending in the tire axial direction. Such a narrow transverse groove 25 helps to improve wet performance and wandering performance.

[0042] As shown in Figure 1, the tread portion 2 of this embodiment is provided with a plurality of lateral grooves 30 extending from a first inclined groove 5 to a second inclined groove 6. The lateral grooves 30 include a first lateral groove 31 inclined with respect to the tire axis and a second lateral groove 32 inclined in the opposite direction to the first lateral groove 31 with respect to the tire axis. The first lateral grooves 31 and the second lateral grooves 32 are provided alternately in the tire circumferential direction. Such first lateral grooves 31 and second lateral grooves 32 help to improve wet performance.

[0043] Although a tire according to one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the specific embodiment described above and can be implemented in various modified forms.

[0044] [Note] This disclosure includes the following aspects:

[0045] [Disclosure 1] A tire having a tread portion with a specified direction of rotation, The tread portion includes a first tread end, a plurality of first inclined grooves extending at least from the first tread end toward the tire equator toward the leading side in the rotational direction, and a plurality of first land portions divided by the plurality of first inclined grooves. Each of the plurality of first inclined grooves includes a first groove wall on the leading side in the rotational direction and a second groove wall on the trailing side in the rotational direction. A first chamfered portion is formed on the first groove wall. A second chamfered portion is formed on the second groove wall. In a cross-section perpendicular to the groove centerline of the first inclined groove, the chamfer area S1 of the first chamfer is larger than the chamfer area S2 of the second chamfer. tire. [Disclosure 2] The tire according to Disclosure 1, wherein the chamfered area S1 is 1.1 times or more the chamfered area S2. [Disclosure 3] The tire according to disclosure 1 or 2, wherein the chamfered area S1 is 1.5 times or less the chamfered area S2. [Disclosure 4] The tire according to any one of disclosures 1 to 3, wherein the first chamfered portion has a chamfered area S1 that increases toward the outward direction in the tire axial direction. [Disclosure 5] The tire according to any one of disclosures 1 to 4, wherein the second chamfered portion has a chamfered area S2 that increases toward the outward direction in the tire axial direction. [Disclosure 6] The tire according to any one of disclosures 1 to 5, wherein in a region of 50% or more of the total length of the first inclined groove, the chamfered area S1 is larger than the chamfered area S2. [Disclosure 7] The tire according to any one of disclosures 1 to 6, wherein the chamfered area S1 is larger than the chamfered area S2 over the entirety of the first inclined groove. [Disclosure 8] The tire according to any one of disclosures 1 to 7, wherein the angle of the first inclined groove with respect to the tire circumferential direction increases toward the outward direction in the tire axial direction. [Disclosure 9] The tire according to any one of disclosures 1 to 8, wherein the angle of the first inclined groove at the first tread end with respect to the tire circumferential direction is 80 to 90°. [Disclosure 10] The first inclined groove includes the inner end on the tire equator side, The tire according to any one of disclosures 1 to 9, wherein the angle of the first inclined groove at the inner end with respect to the tire circumferential direction is 30 to 70°. [Explanation of Symbols]

[0046] 2 Tread section 5 1st inclined groove 7 1st Land Department 11. First trench wall 12. Second trench wall 13. First chamfered section 14. Second chamfered section R rotation direction T1 First tread end S1 Chamfered area of ​​the first chamfered section S2 Chamfered area of ​​the second chamfered section

Claims

1. A tire having a tread portion with a specified direction of rotation, The tread portion includes a first tread end, a plurality of first inclined grooves extending at least from the first tread end toward the tire equator toward the leading side in the rotational direction, and a plurality of first land portions divided by the plurality of first inclined grooves. Each of the plurality of first inclined grooves includes a first groove wall on the leading side in the rotational direction and a second groove wall on the trailing side in the rotational direction. A first chamfered portion is formed on the first groove wall. The second groove wall has a second chamfered portion formed therein. In a cross-section perpendicular to the groove centerline of the first inclined groove, the chamfering area S1 of the first chamfered portion is larger than the chamfering area S2 of the second chamfered portion. In a region of 50% or more of the total length of the first inclined groove, the chamfer area S1 is larger than the chamfer area S2. tire.

2. The tire according to claim 1, wherein the chamfered area S1 is 1.1 times or more the chamfered area S2.

3. The tire according to claim 1 or 2, wherein the chamfered area S1 is 1.5 times or less the chamfered area S2.

4. The tire according to any one of claims 1 to 3, wherein the chamfered area S1 of the first chamfered portion increases toward the outward direction in the tire axial direction.

5. The tire according to any one of claims 1 to 4, wherein the second chamfered portion has a chamfered area S2 that increases toward the outward direction in the tire axial direction.

6. The tire according to any one of claims 1 to 5, wherein the chamfered area S1 is larger than the chamfered area S2 over the entire first inclined groove.

7. The tire according to any one of claims 1 to 6, wherein the angle of the first inclined groove with respect to the tire circumferential direction increases toward the outward direction in the tire axial direction.

8. The tire according to any one of claims 1 to 7, wherein the angle of the first inclined groove at the first tread end with respect to the tire circumferential direction is 80 to 90°.

9. The first inclined groove includes the inner end on the tire equator side, The tire according to any one of claims 1 to 8, wherein the angle of the first inclined groove at the inner end with respect to the tire circumferential direction is 30 to 70°.

Images