tire
The tire design with chamfered edges on inclined grooves addresses the challenge of enhancing turning performance and noise reduction by improving grip and maintaining noise performance through angled and chamfered groove configurations.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SUMITOMO RUBBER INDUSTRIES LTD
- Filing Date
- 2022-03-14
- Publication Date
- 2026-05-19
AI Technical Summary
Existing tires with inclined grooves face challenges in improving turning performance while maintaining noise performance, especially during sharp turns, and there is a need to enhance grip without compromising noise reduction.
The tire design includes inclined grooves with chamfered edges on the trailing side, where the chamfered area increases towards the inner end, and the grooves are angled more gently at the inner end to improve grip, while maintaining a smaller chamfered area at the middle to reduce noise.
The design enhances cornering performance by preventing ground lift during turns and reduces noise by minimizing groove volume increase, thus achieving improved grip and noise performance simultaneously.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to tires.
Background Art
[0002] In Patent Document 1 below, a tire is proposed in which a plurality of inclined grooves are provided in the tread portion, extending obliquely from the first tread end on one side in the tire axial direction toward the tire equator side.
Prior Art Document
Patent Document
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] For tires provided with inclined grooves as in Patent Document 1 above, further improvement in turning performance has been demanded. On the other hand, in recent years, vehicle quieting has been remarkable, and it has been required to maintain the noise performance of tires.
[0005] The present disclosure has been devised in view of the above actual situation, and the main object is to provide a tire with improved turning 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 first middle position which is the center position in the axial direction of the tire between the first tread end and the tire equator, and a plurality of first inclined grooves that extend at least from the first tread end toward the tire equator toward the leading side in the direction of rotation, the inner end of each of the plurality of first inclined grooves in the axial direction of the tire is located toward the tire equator than the first middle position, the angle with respect to the tire circumferential direction at the inner end of each of the plurality of first inclined grooves is smaller than the angle with respect to the tire circumferential direction at the first middle position, 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, and in the inner region of each of the plurality of first inclined grooves toward the inner end than the first middle position, the second groove wall includes a chamfered portion, and in a cross-section perpendicular to the groove centerline of the first inclined groove, the chamfered area of the chamfered portion increases toward the inner end. [Effects of the Invention]
[0007] By adopting the above configuration, the tire disclosed herein can improve cornering 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] This is an enlarged cross-sectional view showing the state of a conventional inclined groove when it is in contact with the ground. [Figure 5] Figure 3 shows enlarged views of the first and second chamfered sections. [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 standards 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. The first inclined grooves 5 are inclined and extend at least from the first tread end T1 toward the tire equator C side in the leading side in the rotational direction R (in each figure of this specification, it is the lower side). The first inclined grooves 5 of the present embodiment are interrupted in front of the tire equator C. The first inclined grooves 5 may, for example, cross the tire equator C. Further, the tread portion 2 includes a plurality of first land portions 7 partitioned by 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. 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. Further, 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. Further, 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. As shown in FIG. 2, the inner ends 5i in the tire axial direction of each of the plurality of first inclined grooves 5 are located on the tire equator C side rather than the first middle position 10. The first middle position 10 is the central position in the tire axial direction between the first tread end T1 and the tire equator C in the tread portion 2.
[0021] In the present disclosure, in each of the plurality of first inclined grooves 5, the angle θ2 with respect to the tire circumferential direction at the inner end 5i is smaller than the angle θ1 with respect to the tire circumferential direction at the first middle position 10.
[0022] Figure 3 shows a cross-sectional view of the first inclined groove 5, specifically the cross-sectional view along line AA in Figure 2. As shown in Figures 2 and 3, in this disclosure, each of the multiple first inclined grooves 5 includes a first groove wall 11 on the leading side R1 in the rotational direction R, and a second groove wall 12 on the trailing side R2 in the rotational direction R. Furthermore, in the inner region 5A of each of the multiple first inclined grooves 5 on the inner end 5i side of the first middle position 10, the second groove wall 12 includes a chamfered portion 15. In this embodiment, the first groove wall 11 also has a chamfered portion 15. Hereinafter, the chamfered portion 15 formed on the first groove wall 11 may be referred to as the first chamfered portion 13, and the chamfered portion 15 formed on the second groove wall 12 may be referred to as the second chamfered portion 14. Note that the chamfered portion 15 is omitted in Figure 1, and in Figure 2, the chamfered portion 15 is conceptually shown by dots for easier understanding.
[0023] In this disclosure, in a cross-section perpendicular to the groove centerline of the first inclined groove 5, the chamfered area of the chamfered portion 15 provided on at least the second groove wall 12 increases toward the inner end 5i. By adopting the above configuration, the tire 1 of this disclosure can improve cornering performance while maintaining noise performance. The mechanism is as follows.
[0024] Figure 4 shows an enlarged cross-sectional view of a conventional inclined groove a without a chamfered edge when it makes contact with the ground. Figure 4 shows the state during braking, with arrow R indicating the direction of tire rotation and arrow A indicating the direction of tire travel. As shown in Figure 4, generally, when a large shear force is applied to an inclined groove a without a chamfered edge, the leading edge b of the inclined groove a (equivalent to the trailing edge of the tread surface on the ground) is pulled under the tread surface on the ground, causing the ground surface c in that area to lift locally from the road surface, and insufficient grip may be achieved.
[0025] In grooves with a relatively small angle to the tire circumferential direction, such as the inner region 5A of the first inclined groove 5 in this disclosure, the above-mentioned problems occur even when turning. That is, in grooves like the inner region 5A of this disclosure, if a chamfered portion is not provided, for example, during a sharp turn, the outer edge of the ground portion may be pulled under the tread surface of the ground portion, causing the ground portion in that vicinity to lift locally from the road surface and not be able to provide sufficient grip. To address this problem, as shown in Figures 2 and 3, in this disclosure, at least the second groove wall 12 of the inner region 5A includes a chamfered portion 15, and the chamfered area of this chamfered portion 15 increases toward the inner end 5i side of the first inclined groove 5. This suppresses the above-mentioned problems, improves grip during turning, and enables excellent turning performance.
[0026] On the other hand, conventionally, when chamfered portions are provided in the grooves, it can lead to an increase in groove volume, which can impair noise performance. However, in this disclosure, since the chamfered area on the first middle position side is relatively small, the increase in noise due to the increase in groove volume caused by the chamfered portion can be suppressed, and noise performance can be maintained. The tire 1 of this disclosure can improve cornering performance while maintaining noise performance through this mechanism.
[0027] Figure 5 shows enlarged views of the first chamfered portion 13 and the second chamfered portion 14. The chamfered portion 15 includes a flat or curved surface (hereinafter, these may be collectively referred to as an inclined surface) that is inclined to connect the main body 16a of the groove wall 16 of the first inclined groove 5 and the tread surface 7s of the first land portion 7, so that no sharp corners are formed between the groove wall 16 of the first inclined groove 5 and the tread surface 7s of the first land portion 7.
[0028] Furthermore, the chamfered area of the chamfered portion 15 is defined as follows: The chamfered area refers to the area of the region enclosed by the inclined surface 15a of the chamfered portion 15, 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 virtual groove wall 16v obtained by extending the main body 16a of the groove wall 16 of the first inclined groove 5 to the virtual tread surface 7v.
[0029] The inclined surface 15a of the chamfered portion 15 refers to the surface from the main body 16a of the groove wall 16 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 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 to the cross section of the first inclined groove 5 while maintaining the curvature of the tread surface 7s.
[0030] The virtual groove wall 16v is a virtual surface extending from the boundary 22 between the main body 16a and the inclined surface 15a of the groove wall 16 to the virtual tread surface 7v. The boundary 22 between the main body 16a and the inclined surface 15a of the groove wall 16 is the position where the angle of the groove wall 16 with respect to the tire radius direction changes abruptly. If the position is an area with a substantial width, the position closest to the groove centerline corresponds to the boundary 22.
[0031] 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.
[0032] 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, 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 5 to 30°. The angle θ1 of the first inclined groove 5 with respect to the tire circumferential direction at the first middle position 10 is, for example, 30° or more, and preferably 30 to 60°. The angle θ3 of the first inclined groove 5 with respect to the tire circumferential direction at the first tread end T1 is preferably 80 to 90°. Furthermore, this improves braking performance and cornering performance in a well-balanced manner.
[0033] 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.
[0034] In this disclosure, the above-mentioned effects can be expected to some extent if the second chamfered portion 14 is located in a part of the inner region 5A. However, from the viewpoint of more reliably achieving the above-mentioned effects, the second chamfered portion 14 is provided in a range of preferably 50% or more of the inner region 5A, and more preferably the entire range of the inner region 5A.
[0035] As shown in Figure 5, in this embodiment, the tread surface 7s of the first land portion 7, the groove wall 16 of the first inclined groove 5, and the inclined surface 15a of the chamfered portion 15 are each substantially planar, and the cross-sectional view of the first inclined groove 5 is linear. As a result, the chamfered portion 15 is configured, for example, as an obtuse triangular shape in cross-sectional view.
[0036] The chamfered area of the second chamfered section 14 is preferably continuously increasing from the first middle position 10 to the inner end 5i. This can further improve turning performance. The chamfered area is 0.5 mm 2 The above is considered appropriate, preferably 0.5-2.0 mm. 2 However, the chamfered area is not limited to this range.
[0037] The configuration of the chamfered portion 15 described above has been explained for the second chamfered portion 14, but it may also be applied to the first chamfered portion 13. In this embodiment, the first chamfered portion 13 and the second chamfered portion 14 have substantially the same configuration.
[0038] As shown in Figure 2, in this embodiment, the second groove wall 12 does not have a chamfered portion in the outer region 5B of each of the multiple first inclined grooves 5 that is on the first tread end T1 side of the first middle position 10. This ensures that noise performance is reliably maintained.
[0039] The first tread section 7, from the tire equator C to the first tread edge T1, is composed of a smooth tread surface without grooves or sipes. Such a first tread section 7 can exhibit excellent traction and braking performance.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] [Note] This disclosure includes the following aspects:
[0044] [Disclosure 1] A tire having a tread portion with a specified direction of rotation, The tread portion includes a first tread end, a first middle position which is the center position in the tire axial direction between the first tread end and the tire equator, and a plurality of first inclined grooves that extend at least from the first tread end toward the tire equator toward the leading side in the rotational direction, The inner end of each of the plurality of first inclined grooves in the tire axial direction is located closer to the tire equator than the first middle position. In each of the plurality of first inclined grooves, the angle with respect to the tire circumferential direction at the inner end is smaller than the angle with respect to the tire circumferential direction at the first middle position. 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. In the inner region of each of the plurality of first inclined grooves, on the inner end side of the first middle position, the second groove wall includes a chamfered portion. In a cross-section perpendicular to the groove centerline of the first inclined groove, the chamfered area of the chamfered portion increases toward the inner end. tire. [Disclosure 2] The tire according to Disclosure 1, wherein in the outer region of each of the plurality of first inclined grooves that is on the side of the first tread end that is further than the first middle position, the second groove wall does not have a chamfered portion formed thereon. [Disclosure 3] The tire according to disclosure 1 or 2, wherein the chamfered portion of the second groove wall is provided over the entire extent of the inner region. [Disclosure 4] The tire according to disclosure 3, wherein the chamfered area of the chamfered portion of the second groove wall increases continuously from the first middle position to the inner end. [Disclosure 5] The tire according to any one of disclosures 1 to 4, wherein the angle of the first inclined groove with respect to the tire circumferential direction increases continuously from the inner end to the first tread end. [Disclosure 6] The chamfered area is 0.5 mm 2 The tire described in any of items 1 to 5 of this disclosure is as described above. [Explanation of symbols]
[0045] 2 Tread section 5 1st inclined groove 5A Inner area 5i inner end 10. First Middle Position 11. First trench wall 12. Second trench wall 15 Chamfered section R rotation direction T1 First tread end
Claims
1. A tire having a tread portion with a specified direction of rotation, The tread portion includes a first tread end and a second tread end, a first middle position which is the center position in the tire axial direction between the first tread end and the tire equator, a plurality of first inclined grooves extending at least from the first tread end toward the tire equator and inclined toward the first-to-first side in the rotational direction, and a plurality of second inclined grooves extending at least from the second tread end toward the tire equator and inclined toward the first-to-first side in the rotational direction. The inner end of each of the plurality of first inclined grooves in the tire axial direction is located closer to the tire equator than the first middle position. In each of the plurality of first inclined grooves, the angle with respect to the tire circumferential direction at the inner end is smaller than the angle with respect to the tire circumferential direction at the first middle position. 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. In the inner region of each of the plurality of first inclined grooves, on the inner end side of the first middle position, the second groove wall includes a chamfered portion. In a cross-section perpendicular to the groove centerline of the first inclined groove, the chamfered area of the chamfered portion increases toward the inner end side. The second inclined groove has the same configuration as the first inclined groove. tire.
2. The tire according to claim 1, wherein in the outer region of each of the plurality of first inclined grooves that is on the side of the first tread end that is further than the first middle position, the second groove wall does not have a chamfered portion formed thereon.
3. The tire according to claim 1 or 2, wherein the chamfered portion of the second groove wall is provided over the entire range of the inner region.
4. The tire according to claim 3, wherein the chamfered area of the chamfered portion of the second groove wall increases continuously from the first middle position to the inner end.
5. The tire according to any one of claims 1 to 4, wherein the angle of the first inclined groove with respect to the tire circumferential direction increases continuously from the inner end to the first tread end.
6. The chamfered area is 0.5 mm 2 The tire according to any one of claims 1 to 5.