JP6511341B2 - tire - Google Patents

Description

  The present invention relates to a tire.

  Disclosed is a tire provided with tread portions including longitudinal grooves (main grooves) extending in the tire circumferential direction, land portions separated by the longitudinal grooves, and lateral grooves formed in the land portions and extending in a direction intersecting the longitudinal grooves. (See Patent Document 1). In this tire, the mounting direction of the vehicle is specified, and the tread pattern is asymmetrical. A water film between the tread surface of the tread portion and the road surface on a wet road surface can be discharged to the main groove through the lateral groove.

JP 2012-116306 A

  However, in the case where the lateral groove extends in the direction intersecting the main groove and communicates with the main groove, an acute angle portion is formed on the land portion of the portion where the lateral groove and the main groove intersect in a tread plan view. For example, when the acute angle portion is caught between the road surface and the tread surface of the tread at the time of cornering, the contactability is lowered, which is not preferable from the viewpoint of steering stability.

  On the other hand, it is conceivable to provide a chamfered portion at the land portion end on the tread surface side of the lateral groove in order to prevent the acute angle portion from being formed in the land portion where the main groove and the lateral groove intersect. In that case, a decrease in the contact area of the tread leads to a decrease in the contactability.

  The present invention improves the steering stability particularly at cornering while maintaining the water film removal performance by suppressing the land portion end on the tread surface side from being caught between the road surface and the tread surface of the tread in the tire. The purpose is

The tire according to claim 1 communicates with the tread with a plurality of main grooves extending in the tire circumferential direction, a land portion divided in the tire width direction by the main grooves, and the tread surface side of the land portion, and A sipe formed in communication with a groove and provided at a land portion end on the tread side along the sipe, the width in the circumferential direction of the tire gradually decreases inward from the tire width direction outer side of the land portion, A chamfered portion whose chamfering amount at the acute angle side where the sipe and the main groove intersect at an acute angle as viewed from the tread surface is larger than that at an obtuse angle side where the sipe and the main groove intersect at an obtuse angle , have a chamfered beginning which is a boundary of the said tread chamfer, at the corners of the acute angle side, and a convex curved shape on the chamfered portion side when viewed from the tread surface.

  In this tire, since the chamfered portion is provided at the land portion end on the tread surface side along the sipe, the land portion end is suppressed from being caught between the road surface and the tread surface of the tread. Since the width of the chamfered portion in the tire circumferential direction gradually decreases inward from the tire width direction outer side of the land portion, a reduction in the contact area of the tire width direction center portion having a relatively high rigidity in the land portion is suppressed. Ru. Furthermore, since the sipe having the chamfered portion communicates with the main groove, the water film removing performance between the road surface and the tread surface of the tread is maintained.

  Further, in this tire, since the amount of chamfering of the acute angle side of the chamfered portion is larger than the amount of chamfering of the obtuse angle side, the corner is prevented from being caught between the road surface and the tread surface of the tread. Be done. Therefore, the steering stability can be improved while maintaining the water film removal performance.

Furthermore, in this tire, as viewed from the tread surface, the chamfering start portion has a convexly curved shape toward the chamfered portion at the corner on the acute angle side, so the land portion is more than the case where the chamfering start portion is linear. Volume increases. For this reason, the ground contact area of the land portion can be increased while suppressing the reduction in rigidity of the land portion.

According to the second aspect of the present invention, the tread communicates with a plurality of main grooves extending in the tire circumferential direction, a land portion divided in the tire width direction by the main grooves, and the tread surface side of the land portion A sipe formed in communication with the land portion end along the tread surface along the sipe, and the width in the circumferential direction of the tire gradually decreases inward from the outer side in the tire width direction of the land portion, the tread surface A chamfered portion whose chamfering amount at the acute angle side where the sipe and the main groove intersect at an acute angle as viewed from a chamfer is larger than that at an obtuse angle side where the sipe and the main groove intersect at an obtuse angle; The area in which the width in the tire circumferential direction of the chamfered portion is the smallest is 50% of the width in the tire width direction of the land in the center of the land width in the tire width direction. is there.

  If the area where the width of the chamfered portion in the tire circumferential direction is the smallest is out of this range, the contact area at the central portion in the widthwise direction of the tire is relatively high. The amount of chamfering at the corner portions decreases, and the rigidity of the corner portions tends to be reduced.

  In this tire, since the area where the width in the tire circumferential direction of the chamfered portion is the smallest is appropriately set, the reduction in contact area is suppressed while the rigidity reduction of the corner portion seen from the tread surface of the land portion is suppressed. The steering stability can be improved.

According to the invention of claim 3 , the tread communicates with a plurality of main grooves extending in the tire circumferential direction, a land portion divided in the tire width direction by the main grooves, and the tread surface side of the land portion, and the main groove A sipe formed in communication with the land portion end along the tread surface along the sipe, and the width in the circumferential direction of the tire gradually decreases inward from the outer side in the tire width direction of the land portion, the tread surface A chamfered portion whose chamfering amount at the acute angle side where the sipe and the main groove intersect at an acute angle as viewed from a chamfer is larger than that at an obtuse angle side where the sipe and the main groove intersect at an obtuse angle; In the tire circumferential direction cross section, the chamfered portion has a convex curved shape.

  In this tire, since the chamfered portion has a convex curved shape in the tire circumferential direction cross section, the volume of the land portion is larger than when the chamfered portion is linear. For this reason, the rigid fall of a land part can be controlled and steering stability can be improved.

The invention according to claim 4 is the tire according to any one of claims 1 to 3 , wherein the depth of the chamfered portion from the tread surface in the tire radial direction is the sipe from the tread surface 10-40% of the depth of

  When the depth of the chamfered portion is out of this range, the corner is caught between the road surface and the tread surface of the tread, and the rigidity of the land portion is reduced due to the reduction of the volume of the land portion.

  In this tire, since the depth of the chamfered portion is appropriately set, the corner portion is prevented from being caught between the road surface and the tread surface of the tread, and the rigidity of the land portion is secured in a balanced manner. be able to.

  According to the tire of the present invention, in the tire, by suppressing the land portion end on the tread surface side from being caught between the road surface and the tread surface of the tread, it is possible to maintain the water film removal performance, especially at cornering The excellent effect that stability can be improved is obtained.

It is a top view showing the tread pattern of the tire concerning this embodiment. In a tread, it is an enlarged plan view showing a sipe and a chamfer provided in a land part. It is an expansion perspective view showing a sipe and a chamfer provided in a land part. It is an enlarged side view showing a sipe and a chamfer provided in a land part.

  Hereinafter, a mode for carrying out the present invention will be described based on the drawings. In the drawings, the arrow C direction indicates the tire circumferential direction, the arrow R direction indicates the tire radial direction, and the arrow W direction indicates the tire width direction. The tire radial direction means a direction orthogonal to the tire rotation axis (not shown). The tire width direction means a direction parallel to the tire rotation axis. The tire width direction can also be reworded as the tire axial direction. Moreover, OUT means the vehicle mounting outer side, IN means the vehicle mounting inner side.

  T means a ground end. With the ground contact end, the tire is mounted on the standard rim specified in JATMA YEAR BOOK (2015 edition, Japan Automobile Tire Association Standard), and maximum load capacity (internal pressure-load) in application size and ply rating in JATMA YEAR BOOK The inner end of the tire in the tread width direction at the time of loading the internal pressure of 100% of the air pressure (maximum air pressure) corresponding to the bold load in the capacity correspondence table and applying a load of 70% of the load index. If TRA standard or ETRTO standard is applied at the place of use or production site, follow each standard.

  The dimension measurement method of each part is the method described in the 2015 YEAR BOOK issued by JATMA (Japan Automobile Tire Association).

  In FIG. 1, the tire 10 according to the present embodiment relates to, for example, a pneumatic tire, and the tread 12 includes four main grooves 14, 16, 18 and 20 as an example of a plurality of main grooves and an example of a land portion. An outer intermediate land portion 22, a central land portion 24, an inner intermediate land portion 26, an outer shoulder land portion 28, an inner shoulder land portion 30, a sipe S, and chamfers 32, 33 are provided.

  The main grooves 14, 16, 18, 20 are provided in order from the vehicle mounting outer side toward the inner side, and extend in the tire circumferential direction. The groove widths of the two main grooves 16 and 18 positioned on the center side in the tire width direction are set larger than the groove widths of the two main grooves 14 and 20 positioned on the outer side in the tire width direction.

  The outer intermediate land portion 22, the central land portion 24, the inner intermediate land portion 26, the outer shoulder land portion 28 and the inner shoulder land portion 30 are respectively divided in the tire width direction by the main grooves 14, 16, 18, 20. Specifically, the outer intermediate land portion 22 is partitioned by the main grooves 14 and 16. The central land portion 24 is partitioned by the main grooves 16 and 18, and the inner intermediate land portion 26 is partitioned by the main grooves 18 and 20. The outer shoulder land portion 28 is defined by the main groove 14 and is located at the outer side in the tire width direction of the main groove 14, in other words, at the end of the tread 12 at the vehicle mounting outer side. The inner shoulder land portion 30 is defined by the main groove 20 and is located at the outer side in the tire width direction of the main groove 20, in other words, at the end of the tread 12 at the vehicle mounting inner side.

  In FIGS. 1 to 4, the sipe S is in communication with the tread surface 34 side of the outer intermediate land portion 22 and in communication with the main grooves 14 and 16. The sipe S is a narrow groove having a width of, for example, 1.2 mm or less which is closed when the outer intermediate land portion 22 is in contact with the ground, and has a shape cut inward in the tire radial direction from the tread surface 34 side. The depth of the sipe S from the tread 34 is set to be shallower than the depth of the main grooves 14 and 16 from the tread 34 as well. The sipe S extends in a direction inclined with respect to the tire width direction, and the outer intermediate land portion 22 is partitioned by the sipe S in the tire circumferential direction. The shape of the sipe S seen from the tread surface 34 is a substantially linear shape or a curved shape that is convex in one of the tire circumferential directions.

  In FIG. 2, the chamfered portions 32 and 33 are respectively provided at the land portion end on the tread surface 34 side along the sipe S, and the width WS in the tire circumferential direction is inward from the tire width direction outer side of the outer intermediate land portion 22. It is decreasing gradually. As an example, in one chamfered portion 32, the amount of chamfering of the corner 36 on the acute angle side where the sipe S and the main groove 14 intersect at an acute angle as viewed from the tread surface 34 is the obtuse angle side where the sipe S and the main groove 16 intersect at an obtuse angle Is larger than the chamfering amount of the corner 38. The same applies to the other chamfered portion 33.

  That is, in the illustrated example, at the land portion end on one side in the tire circumferential direction sandwiching the sipe S, the amount of chamfering of the chamfered portion 32 gradually decreases inward from the tire width direction outer side of the corner 36 on the acute angle side. ing. Here, the chamfering amount means the volume of the chamfered portion. The depth of the chamfered portion 32 is, for example, constant, and the chamfering amount increases as the width WS of the chamfered portion 32 in the tire circumferential direction viewed from the tread surface 34 increases. Therefore, the magnitude of the chamfering amount can be compared by the magnitude of the width WS. Accordingly, the chamfering start portions 32A and 33A, which are the boundaries between the tread surface 34 and the chamfered portions 32 and 33, are convexly curved toward the chamfered portions 32 and 33 as viewed from the tread surface 34 at the corner portion 36 on the acute angle side. It is supposed to be in shape. The width WS of the chamfered portion 32 is the distance in the tire circumferential direction from the chamfering start portion 32A to the wall portion of the sipe S on which the chamfered portion 32 is located. Similarly, the width WS of the chamfered portion 33 is the distance in the tire circumferential direction from the chamfering start portion 33A to the wall portion of the sipe S on which the chamfered portion 33 is located.

  In the chamfered portion 32, the amount of chamfering on the obtuse angle side 38 is constant, slightly increased, or slightly decreased from the substantially central portion in the tire width direction of the outer intermediate land portion 22 to the end on the main groove 16 side. . On the other hand, at the land portion end on the other side in the tire circumferential direction sandwiching the sipe S, the amount of chamfering of the chamfered portion 33 gradually decreases from the corner portion 36 side on the acute angle side toward the corner portion 38 side on the obtuse angle side.

  In addition, as shown in FIG. 3, the corner 36 on the acute side and the corner 38 on the obtuse side are not only present on one and the other in the tire width direction at the land end, but the tire circumference sandwiching the sipe S It exists adjacent to one side and the other side of the direction.

  A region P where the width WA in the tire circumferential direction of the chamfered portions 32 and 33 is the smallest is the width A in the tire width direction of the outer intermediate land portion 22 around the center CL of the outer intermediate land portion 22 in the tire width direction. It is in the range of 50%. Here, the width WA is the sum of the width WS of the chamfered portion 32 and the width WS of the chamfered portion 33 at a certain position in the tire width direction. In the illustrated example, the area P is present as a point, but is not limited to this, and may be an area having a certain width in the tire width direction.

  As shown in FIG. 3, in the tire radial direction, the depth D of the chamfers 32 and 33 from the tread surface 34 is 10 to 40% of the depth DS of the sipe S from the tread surface 34. When the depth D of the chamfered portions 32 and 33 is out of this range, the sharp corner 36 is entrained between the road surface and the tread 34 of the tread 12 and the rigidity of the land 16 decreases due to the reduction in volume. .

  In the tire circumferential direction cross section, the chamfered portions 32 and 33 each have a convex curved shape. Although FIG. 4 is a side view, it is equivalent to the cross-sectional shape of the tire width direction end of the outer intermediate land portion 22. In this figure, the radius of curvature of the chamfered portion 33 located at the corner portion 36 on the acute angle side is larger than that of the chamfered portion 32 located on the corner portion 38 at the obtuse angle side. It is not limited. For example, the radius of curvature can be made larger than that of the chamfered portion 33 by bringing the cross-sectional shape of the chamfered portion 32 closer to a straight line.

  In addition, in FIG. 1, notches 40 are respectively formed on the extension of the sipe S in the outer shoulder land portion 28 and the central land portion 24. Further, in the outer shoulder land portion 28 and the inner shoulder land portion 30, lateral grooves 42 extending in the tire width direction are respectively formed.

  A sipe 44 is formed in the central land portion 24. The sipe 44 does not communicate with the main groove 16 but communicates only with the main groove 18. A chamfered portion 46 is provided at the land portion end on the tread 34 side of the sipe 44.

  In the inner intermediate land portion 26, two sipes 48 and 49 having an arc shape seen from the tread surface 34 and having mutually opposite convex directions are formed in communication with each other. The sipe 48 communicates with the main groove 18, and the sipe 49 communicates with the main groove 20. A chamfered portion 50 is provided at the land portion end of the sipe 48, 49 on the tread surface 34 side, and a chamfered portion 52 is provided at the land portion end of the sipe 49 on the tread surface 34 side.

(Action)
The present embodiment is configured as described above, and the operation thereof will be described below. In FIG. 1 to FIG. 4, in the tire 10 according to the present embodiment, the chamfered portions 32 and 33 are provided at the land portion end on the tread surface 34 side along the sipe S. And the rolling of the tread surface 34 of the tread 12 is suppressed. Since the width in the tire circumferential direction of the chamfered portions 32 and 33 gradually decreases inward from the outer side of the outer intermediate land portion 22 in the tire width direction, the center in the tire width direction of the outer intermediate land portion 22 is relatively high in the tire width direction. The reduction of the ground contact area of the part is suppressed. Furthermore, since the sipe S having the chamfered portion communicates with the main grooves 14 and 16, the water film removing performance between the road surface and the tread surface 34 of the tread 12 is maintained.

  In addition, since the amount of chamfering of the corner portion 36 on the acute angle side in the chamfered portions 32 and 33 is larger than that of the corner portion 38 on the obtuse angle side, the corner portion 36 on the acute angle side is between the road surface and the tread surface 34 of the tread 12 Being caught in the Therefore, the steering stability can be improved while maintaining the water film removal performance.

  Furthermore, as viewed from the tread surface 34, the chamfering start portions 32A and 33A are convexly curved toward the chamfered portions 32 and 33 at the corner portion 36 on the acute angle side, so the chamfered portions 32 and 33 are linear. The volume of the outer intermediate land portion 22 is larger than in the case where Therefore, the ground contact area of the outer intermediate land portion 22 can be increased while suppressing the decrease in the rigidity of the corner portion 36.

  Further, since the region P where the width WA in the tire circumferential direction of the chamfered portions 32 and 33 is the smallest is appropriately set, especially the corner portion 36 on the acute angle side viewed from the tread surface 34 of the outer intermediate land portion 22. It is possible to suppress the reduction in the ground contact area and to improve the steering stability while suppressing the reduction in the rigidity.

  Furthermore, in the tire circumferential cross section, since the chamfered portions 32 and 33 have a convex curved shape, the volume of the outer intermediate land portion 22 is larger than when the chamfered portions 32 and 33 are linear. For this reason, the rigid fall of outer side middle land part 22 can be controlled, and steering stability can be improved.

  Further, since the ratio of the depth D of the chamfered portions 32 and 33 to the depth DS of the sipe S is appropriately set, the corner portion 36 on the acute angle side is caught between the road surface and the tread 34 of the tread 12 And the rigidity of the outer intermediate land portion 22 can be secured in a well-balanced manner.

[Other embodiments]
As mentioned above, although an example of the embodiment of the present invention was described, the embodiment of the present invention is not limited to the above, and besides the above, it can be variously modified and carried out in the range which does not deviate from the main point Of course there is one.

(Test example)
Tests were performed on the performance of the tire according to the present embodiment. The tire size, rim width and tire internal pressure were all common under the following conditions. The tire according to the conventional example used a tire having no chamfered portion at the land portion end formed by sipes.

For evaluation of steering stability, the following tire is mounted on a front wheel drive vehicle with a displacement of 2000 cc, and travels on the testability evaluation path (dry normal path) of the test course while riding on one person, and the sensory evaluation of the test driver ( Steering stability was indexed by feeling evaluation.
Tire size: 225/45 R17
Rim width: 7.5J
Internal pressure: 220 kPa

[Test Example 1]
About the chamfer of a sipe, it tested about steering stability in, when the position of area | region P (refer FIG. 2) where the width | variety of a tire circumferential direction becomes the smallest is changed. In each of the reference examples and embodiments, the positions of the regions P are different from one another.

  The position of the region P and the test results are as shown in Table 1. With respect to the position in the region P, the distance in the tire width direction from the center CL in the tire width direction of the land portion is shown as a ratio to the width A in the tire width direction of the land portion. Note that “25%” of the first embodiment corresponds to a range of 50% of the width A centered on the center CL. “0%” in the second embodiment indicates that the region P is located at the center CL.

  The evaluation result is indicated by an index when the evaluation of the conventional example is 100, and the larger the value, the better. From this result, it was found that the steering stability is higher in Examples 1 and 2 than in the conventional example and each reference example.

[Test Example 2]
The steering stability was tested when the depth of the chamfer of the sipe was changed.

  The test conditions and the test results are as shown in Table 2. The evaluation results are indicated by indexes when the evaluation of the conventional example is 100, and the larger the value, the better. From these results, it was found that the steering stability is higher in Examples 1 to 3 than the conventional example and each reference example.

DESCRIPTION OF REFERENCE NUMERALS 10 tire 12 tread 11 main groove 16 main groove 18 main groove 20 main groove 22 outer intermediate land portion (land portion) 32 chamfered portion 32A chamfered start portion 33: chamfered portion, 33A: chamfered start portion, 34: tread surface, 36: acute angle side corner, 38: obtuse angle side corner, CL: center, P: area, S: sipe

Claims (4)

On the tread
A plurality of main grooves extending in the tire circumferential direction;
Land portions partitioned in the tire width direction by the main grooves;
A sipe communicated with the tread surface side of the land portion and in communication with the main groove;
The tire is provided at a land portion end on the tread surface side along the sipe, and the width in the circumferential direction of the tire gradually decreases inward from the tire width direction outer side of the land portion, and the sipe and the main groove are viewed from the tread surface. There chamfering of the corners of the acute angle side intersecting at an acute angle is, have a, a large chamfered portion than the chamfering amount of the corners of obtuse angle side of the sipe and said main groove intersect at an obtuse angle,
The tire in which the chamfer start part which is a boundary of the said tread surface and the said chamfer is made into the convex-curved shape seen in the said tread surface in the corner on the said acute angle side seeing from the said tread surface . On the tread
A plurality of main grooves extending in the tire circumferential direction;
Land portions partitioned in the tire width direction by the main grooves;
A sipe communicated with the tread surface side of the land portion and in communication with the main groove;
The tire is provided at a land portion end on the tread surface side along the sipe, and the width in the circumferential direction of the tire gradually decreases inward from the tire width direction outer side of the land portion, and the sipe and the main groove are viewed from the tread surface. The chamfering amount of the corner on the acute angle side where the angle intersects the acute angle is larger than the chamfering amount of the corner on the obtuse angle side where the sipe and the main groove intersect at an obtuse angle,
Area where the tire circumferential direction of the width of the smallest of the chamfered portion, the centering on the center of the tire width direction of the land portion, 50% of the range near Ru tire in the tire width direction of the width of the land portion. On the tread
A plurality of main grooves extending in the tire circumferential direction;
Land portions partitioned in the tire width direction by the main grooves;
A sipe communicated with the tread surface side of the land portion and in communication with the main groove;
The tire is provided at a land portion end on the tread surface side along the sipe, and the width in the circumferential direction of the tire gradually decreases inward from the tire width direction outer side of the land portion, and the sipe and the main groove are viewed from the tread surface. The chamfering amount of the corner on the acute angle side where the angle intersects the acute angle is larger than the chamfering amount of the corner on the obtuse angle side where the sipe and the main groove intersect at an obtuse angle,
In the tire circumferential direction cross-section, the chamfer, that is a convex curved shape tire. The tire according to any one of claims 1 to 3 , wherein a depth of the chamfered portion from the tread surface is 10 to 40% of a depth of the sipe from the tread surface in the tire radial direction.

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