WO2015136996A1

WO2015136996A1 - Tire

Info

Publication number: WO2015136996A1
Application number: PCT/JP2015/052352
Authority: WO
Inventors: 康典阿部
Original assignee: 株式会社ブリヂストン
Priority date: 2014-03-12
Filing date: 2015-01-28
Publication date: 2015-09-17
Also published as: JP2015171865A

Abstract

Provided is a tire, wherein the uneven wear of a shoulder from the initial phase of use to the final phase of use can be reduced by reducing uneven wear in the initial phase of use. A circumferential narrow groove (10) formed in a land portion between a shoulder groove and a tread ground-contacting end (TG) and extending along the tire circumferential direction is provided with: an annular groove (13) that is provided on the side of the circumferential narrow groove (10) oriented toward a groove bottom (10d), extends continuously in the tire circumferential direction, and has a groove width wider than the distance between an inside groove wall (11) and an outside groove wall (12); and a protruding portion (14) that is provided on the outside groove wall (12) and protrudes toward the inside groove wall (11). The protruding portion (14) comes into contact with the inside groove wall (11) under a load, and is substantially continuous in the tire circumferential direction.

Description

tire

The present invention relates to a tire that can improve shoulder uneven wear not only in the early stage of wear but also in the end stage of wear.

2. Description of the Related Art Conventionally, a technique is known in which a narrow groove called a defense side groove (hereinafter referred to as DSG) is provided at an end portion in the width direction of a tread portion in order to improve uneven wear properties of a tire shoulder portion.
Further, as shown in FIG. 6, an annular groove 13 </ b> A that extends continuously in the tire circumferential direction is provided on the groove bottom side of the groove wall 11 on the inner side in the tire width direction of the DSG 10 </ b> A provided in the shoulder land portion 5. A technique for improving the tear resistance of the bottom and suppressing the occurrence of cracks has been proposed (see, for example, Patent Document 1).

WO 2008/111582 A1

However, in the tire of Patent Document 1, the swelling of rubber in the shoulder width direction increases, while the swelling of rubber in the circumferential direction decreases. As a result, it becomes difficult to suppress slipping in the tire circumferential direction, so that the partial wear of the shoulder portion at the initial running is not sufficient.

The present invention has been made in view of the conventional problems, and provides a tire capable of improving the uneven shoulder wear from the beginning of travel to the end of travel by improving the uneven wear at the beginning of traveling. Objective.

The present invention relates to a plurality of circumferential grooves formed on the tread surface so as to extend along the tire circumferential direction, a circumferential groove provided on a tire width direction end side of the circumferential grooves, and a tread grounding. A tire including a circumferential narrow groove (DSG) formed in a land portion between the ends and extending along a tire circumferential direction, wherein the circumferential narrow groove is a groove of the circumferential narrow groove The groove width is provided on the bottom side and extends continuously in the tire circumferential direction, and the groove width is a groove wall located on the inner side in the tire width direction of the circumferential narrow groove and a groove wall located on the outer side in the tire width direction. An annular groove wider than an interval with a certain outer groove wall (hereinafter referred to as a DSG groove width), and a protrusion that is provided on the outer groove wall and protrudes toward the inner groove wall and substantially continuous in the tire circumferential direction And the protrusion is provided only on the outer groove wall, and Characterized by contacting the groove wall.
As a result, since the circumferential narrow groove is closed during loading, the shearing force caused by the bulging of rubber in the width direction of the shoulder portion can be reduced and the shearing force caused by the bulging of the rubber in the circumferential direction can be increased. The partial wear property of the part can be improved.
In addition, since the protrusion is provided only on the groove wall on the outer side in the tire width direction of the circumferential narrow groove, the rigidity of the land portion on the outer side in the tire width direction of the DSG can be increased. Therefore, when the projection and the groove wall come into contact with each other, a force in the direction opposite to the brake direction can be efficiently generated, and thus the slip in the brake direction can be reliably suppressed.
In addition, since the rigidity of the land part of a tire width direction outer side will become low if a projection part is provided in an inner side groove wall, the effect which suppresses the slip of a brake direction will fall.

It should be noted that the summary of the invention does not list all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

It is principal part sectional drawing of the tire which concerns on this Embodiment. It is an enlarged view of DSG which concerns on this Embodiment. It is a figure which shows the position of a projection part, length, and thickness. It is a figure which shows the reduction effect of the wear energy by having provided the projection part. It is a figure which shows the other example of the circumferential direction thin groove by this invention. It is a figure which shows the shape of the conventional DSG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a main part (a cross-sectional view in the tire width direction) of a tire 1 according to the present embodiment, where CL in the figure is a tire equatorial plane.
In the figure, 2 is a tread, 3a and 3b are circumferential grooves formed on the tread 2 on the tread surface side so as to extend along the tire circumferential direction. Hereinafter, the circumferential groove 3a located on the tire equatorial plane CL side is referred to as a main groove, and the circumferential groove 3b located on the outer side in the tire width direction is referred to as a shoulder groove.
The central land portion 4 is defined by the main groove 3a and the shoulder groove 3b, and the shoulder land portion 5 is defined by the shoulder groove 3b.
A circumferential narrow groove (hereinafter referred to as DSG) 10 extending along the tire circumferential direction is formed between the tread grounding end TG of the shoulder land portion 5, and the shoulder land portion 5 serves as an inner shoulder by the DSG 10. It is divided into a land portion 5a and an outer shoulder land portion 5b.

FIG. 2 is an enlarged view of the DSG 10 in the tire width direction cross section. The DSG 10 includes a linear inner groove wall 11 extending inward in the tire radial direction from the opening end 10i on the tire width direction inner side of the DSG 10, and an outer side in the tire width direction. From the linear outer groove wall 12 extending inward in the tire radial direction from the open end 10o, the annular groove 13 provided on the groove bottom 10d side and continuously extending in the tire circumferential direction, and the groove wall of the outer groove wall 12 And a protrusion 14 protruding toward the inner groove wall 11 side.
In this example, the height of the outer shoulder land portion 5b in the tire radial direction is formed to be lower than the height dimension of the inner shoulder land portion 5a by d, thereby promoting the wear of the outer shoulder land portion 5b. The uneven wear of the shoulder land portion 5a is suppressed.
The annular groove 13 includes a groove side bottom portion 13m communicating with a groove portion (hereinafter referred to as an opening side groove portion) 15 surrounded by the inner groove wall 11 and the outer groove wall 12, and a tire width from the groove bottom 10d side of the inner groove wall 11. A widened portion 13n that swells inward in the direction is provided.
The protrusion 14 is provided only on the groove wall of the outer groove wall 12.

Further, in this example, the annular groove has a first circular arc portion having a curvature radius R1 of 1.0 to 12.0 mm, the center of curvature being on the inner side in the tire width direction of the inner groove wall, and one end connected to the inner groove wall. The radius of curvature R2 provided between the terminal end of the first arc portion and the innermost end in the tire width direction of the annular groove is 1.5-4. A radius of curvature provided between the second circular arc portion of 0 mm and the center of curvature in the annular groove and between the innermost end in the tire width direction of the annular groove and the innermost end in the tire radial direction of the annular groove. A third arcuate portion having R3 of 1.0 to 16.0 mm, an outer groove wall having a center of curvature in the annular groove and provided between the terminal end of the third arcuate portion and the outer groove wall And a fourth arc portion with a radius of curvature R4 of 2.0 to 16.0 mm, which is connected to the end of the tire, and the innermost end in the tire width direction of the annular groove The tire width direction distance to the outer groove wall is 5.7 to 6.5 mm, and the angle θ between the extending direction of the inner groove wall and the tread surface is 60 ° or more and less than 90 °. It is configured. The above dimensions are values when a tire is mounted on an applicable rim and is in a specified internal pressure and no load unless otherwise specified.
As described above, four circular arc portions are provided in the annular groove, and the shape of the annular groove is made smooth, so that it is possible to improve the stone biting property and the groove bottom tear resistance and the groove bottom crack resistance. Can also be improved.

That is, in this example, four arc portions 16 to 19 are provided in the DSG 10, and the shape of the groove wall at the portion connecting the opening side groove portion 15 and the annular groove 13 and the shape of the groove wall of the annular groove 13 are smooth. Thus, the stone biting property is improved, and the groove bottom tear resistance and the groove bottom crack resistance are also improved.
The first arc portion 16 connects the inner radial end of the inner groove wall 11 and the end of the annular groove 13 on the inner groove wall 11 side, and the center of curvature is the inner width of the inner groove wall 11 in the tire width direction. Are formed of circular arcs having a curvature radius R1 of 1.0 to 12.0 mm. An end portion on the tire radial direction outer side which is a starting end of the first arc portion 16 and an end portion on the inner radial direction of the inner groove wall 11 are connected by a smooth curve.
The second arc portion 17 is an arc having a center of curvature in the annular groove 13 and a radius of curvature R2 of 1.5 to 4.0 mm. It is directed to the inner end 10c and constitutes a groove wall on the inner side in the tire width direction of the annular groove 13. An end portion on the outer side in the tire radial direction, which is the starting end of the second arc portion 17, and an end portion on the inner side in the tire radial direction, which is the terminal end of the first arc portion 16, are connected by a smooth curve.

The third arc portion 18 is a third circular arc having a radius of curvature R3 of 1.0 to 16.0 mm with the center of curvature in the annular groove 13, and is annular from the innermost end 10c in the tire width direction of the annular groove 13. It is formed between the innermost end in the tire radial direction of the groove 13 and constitutes a groove wall on the inner side in the tire radial direction of the annular groove 13.
An end portion on the inner side in the tire width direction which is the starting end of the third arc portion 18 and an end portion on the inner side in the tire radial direction which is the end portion of the second arc portion 17 are connected by a smooth curve.
The fourth arc portion 19 connects the end of the outer groove wall 12 on the inner side in the tire radial direction and the end of the annular groove 13 on the outer groove wall 12 side, and has a curvature radius R4 of 2.0 to 16.0 mm. Consists of arcs. A tire radial direction inner end that is the starting end of the fourth arc portion 19, an end portion on the outer side in the tire width direction that is the end of the third arc portion 18, and a tire diameter that is the end of the fourth arc portion 19 The end portion on the outer side in the direction and the end portion on the inner side in the tire radial direction of the outer groove wall 12 are connected by a smooth curve.

Further, in this example, the groove width W of the opening side groove portion 15 is set to 1.0 to 5.0 mm, and the groove width of the annular groove 13 from the innermost end 10c in the tire width direction to the outer groove wall 12 is set. The distance in the tire width direction is 5.7 to 6.5 mm (see FIG. 3).
This is because if the groove width of the annular groove 13 is less than 5.7 mm, the effect of reducing the contact pressure by the annular groove 13 cannot be obtained, and shoulder uneven wear at the initial stage of wear cannot be suppressed. Further, if the groove width exceeds 6.5 mm, the width in the tire width direction of the outer shoulder land portion 5b becomes excessively small at the end of wear, and shoulder uneven wear is promoted.
Moreover, it is preferable that the angle θ formed between the extending direction of the inner groove wall 11 and the tread surface is 60 ° or more and less than 90 °.
When θ is less than 60 °, it is difficult for foreign matter to be discharged when foreign matter enters DSG 10, and cracks are likely to occur. Further, when θ is 90 ° or more, the tread rubber is less likely to bulge in the tire width direction, and it is difficult to suppress uneven shoulder wear.

In the present embodiment, in the present embodiment, in the cross section in the tire width direction, the length of the inner groove wall in the tire radial direction is L, and the end portion of the protrusion portion on the opening side of the circumferential narrow groove and the outer groove wall When the protrusion depth, which is the distance from the opening end, is H, the protrusion depth H satisfies the relationship 0 ≦ H ≦ L / 3.
Thereby, at the time of load rolling, it can prevent that the opening part of DSG contacts previously rather than a projection part contacting an inner side groove wall. As a result, the braking force in the tire circumferential direction acts on the land portion located on the outer side in the tire width direction of the DSG to suppress the wear on the land portion located on the inner side in the tire width direction of the DSG. Can be improved.

The protruding portion 14 includes a rising portion 14a that rises from the groove wall of the outer groove wall 12 toward the inner groove wall 11, a flat end portion 14b that includes a plane parallel to the outer groove wall 12, and an outer groove wall that falls from the flat end portion 14b. 12 and a falling portion 14c connected to the groove wall, and the flat end portion 14b contacts the inner groove wall 11 when loaded.
When viewed in the cross section in the tire width direction, the end portion P on the opening end 10o side of the protrusion 14 is located on the inner side in the tire radial direction by a distance H from the surface of the outer shoulder land portion 5b. Hereinafter, the distance H is referred to as the protrusion depth. When the length of the inner groove wall 11 in the tire radial direction is L, in this example, the protrusion depth H is in the range of 0 ≦ H ≦ L / 3. This is because when the protrusion depth H exceeds 1 / 3L, the groove walls of the opening of the DSG come into contact with each other before the protrusion 14 contacts the inner groove wall at the time of load. This is because it is difficult to generate a force in the direction opposite to the force, and the effect of improving the uneven wear of the shoulder portion at the initial stage of traveling is reduced.
In addition, as shown in FIG.3 (b), it is good also considering the edge part P by the side of the opening end 10o of the projection part 14 as the same position as the opening end 10o.
Thus, if the protrusion depth H is 1/3 L or less, it is possible to prevent the opening of the DSG 10 from coming into contact first during rolling of the load. Therefore, the braking force in the tire circumferential direction works on the land portion located on the outer side in the tire width direction of the DSG 10, and the wear on the land portion located on the inner side in the tire width direction of the DSG 10 is suppressed. Can be improved.
As in this example, when the height dimension of the outer shoulder land portion 5b in the tire radial direction is lower than the height dimension of the inner shoulder land portion 5a by d, the tire tread when no load is applied is the inner shoulder surface. It becomes the land part 5a. Therefore, the protrusion depth H ′ viewed from the tire tread surface is in the range of d ≦ H ′ ≦ d + L / 3.
The length L of the inner groove wall 11 in the tire radial direction is preferably 6 to 10 mm. This is because, when L is too small, an annular groove having a wide groove width approaches the ground contact surface at an early stage of traveling, and a corner portion (indicated by reference numeral 16 in FIG. 2) having a low rigidity comes to ground. This is because the wear of the steel becomes faster. In addition, when L is too large, the annular groove is separated from the road surface, so that the action of reducing the contact pressure at the contact end is reduced in the initial traveling stage.

Further, in this example, when the protrusion length, which is the length of the protrusion along the tire radial direction, is K in the tire width direction cross section, the protrusion depth H and the protrusion length K are L / 3 ≦ When the relationship of H + K ≦ L is satisfied, the protrusion thickness, which is the protrusion dimension of the protrusion from the outer groove wall, is w, and the distance between the inner groove wall and the outer groove wall is W, the protrusion thickness w is W It is configured to satisfy the relationship of / 3 ≦ w ≦ 2W / 3.
Thereby, since a projection part and an inner side groove wall can be made to contact reliably, the partial wear property of a shoulder part can further be improved.
That is, as shown in FIGS. 3A and 3B, when the length of the protrusion 14 along the tire radial direction is the protrusion length K, the protrusion depth H and the protrusion length K are L / 3 ≦ H + K ≦ L is satisfied, and the protrusion thickness w, which is a protruding dimension of the protrusion 14 from the outer groove wall 12, preferably satisfies the relationship W / 3 ≦ w ≦ 2W / 3. . W is the groove width of the opening-side groove 15 as described above.
If H + K is less than L / 3, the contact area between the protrusion 14 and the inner groove wall 11 is insufficient, and as a result, the force in the direction opposite to the brake direction becomes weak, and the effect of suppressing slippage in the brake direction is reduced. Because it does. If H + K exceeds L, the groove bottom 10d side of the protrusion 14 does not come into contact with the inner groove wall 11, so that the effect of providing the protrusion 14 cannot be obtained. Therefore, the sum H + K of the protrusion length K and the protrusion depth H is preferably in the range of L / 3 ≦ H + K ≦ L.
Further, if the protrusion thickness w is less than W / 3, the DSG may not be closed when the load is small. On the other hand, if w exceeds 2W / 3, the rigidity of the outer shoulder land portion 5b becomes too high, so that the partial wear of the inner shoulder land portion 5a cannot be sufficiently suppressed. Therefore, it is preferable that the protrusion depth H and the protrusion thickness w be in the range of W / 3 ≦ w ≦ 2W / 3.
The rising portion 14a and the falling portion 14c are provided to increase the rigidity of the protruding portion 14, and are not essential elements of the protruding portion 14. Therefore, as shown in FIGS. 3A and 3B, the rising portion 14a and the falling portion 14c may be omitted.

[Experimental example]
FIG. 4 is a diagram showing the effect of reducing the wear energy due to the provision of the protrusions. The horizontal axis is the tread tire width direction position [mm], and the vertical axis is the wear energy [9.8 × 10 ⁵ erg / cm ² ]. is there. The solid line in the figure is the wear energy of the tire of the present invention in which the projections are provided on the DSG shown in FIG. 2, and the broken line is the wear energy of a conventional tire having no projections on the DSG.
The tire size used in the test is 295 / 75R22.5, and the internal pressure is 690 kPa.
The wear energy is measured by measuring the force acting on the tire contact surface during rolling of the tire and the slip between the tire contact surface and the road surface, and the energy generated by friction from the product of the force and the slip (wear energy). ) Was used, a known wear energy tester was used.
As can be seen from the figure, in the tire of the present invention in which the protrusion is provided on the DSG, the wear energy from the tread ground contact end TG to the center of the shoulder land portion is significantly reduced.
The wear energy EW can be expressed as EW = F _c × S where the frictional force is F _c and the slip amount is S (the contact pressure may be used instead of the frictional force F _c ). Therefore, it can be seen that the slip amount is greatly reduced by providing the projections on the DSG.
Thus, it has been confirmed that when the protruding portion comes into contact with the groove wall, the force in the direction opposite to the braking direction can be efficiently generated and the sliding in the braking direction can be reliably suppressed.

As mentioned above, although this invention was demonstrated using embodiment and the experiment example, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

For example, as shown in FIG. 5A, the present invention has an annular groove 13A that widens only on the inner groove wall 11 side, but the angle θ formed between the extending direction of the inner groove wall 11 and the tread surface is 90 °. The present invention is also applicable to the conventional DSG 10A.
Moreover, although the said embodiment demonstrated DSG10 which has the annular groove 13 provided with the widening part 13n swelled in the tire width direction inner side from the groove bottom side of the inner side groove wall 11, this invention is shown in FIG.5 (b). The present invention is also applicable to a DSG 10B having an annular groove 13B having a widened portion on both the groove bottom side of the inner groove wall 11 and the groove bottom side of the outer groove wall 12 as shown.
In short, if only the outer groove wall of the DSG having an annular groove having a groove width wider than the distance between the inner groove wall and the outer groove wall is provided with a protruding portion protruding toward the inner groove wall side, Slip can be reliably suppressed, and uneven wear of the shoulder portion at the initial stage of traveling can be improved.
As shown in FIG. 5C, in the DSG 10C having no annular groove, when a large lateral force is applied, stress concentrates on the groove bottom 10d and a groove bottom crack is generated. Further, when the protrusion 14 is provided on the DSG 10C having no annular groove, the outer shoulder land portion 5b becomes too rigid, so that the groove walls do not contact each other unless the groove width is narrowed. However, if the groove width is narrowed, the stress concentration described above increases, so the shear force in the shoulder portion width direction is not relaxed. That is, the effect of the present invention cannot be obtained even if the protrusion 14 is provided on the DSG 10C having no annular groove.

1 tire, 2 tread, 3a main groove, 3b shoulder groove,
4 central land, 5 shoulder land, 5a inner shoulder land,
5b Outer shoulder land, 10 circumferential narrow groove (DSG),
10i, 10o open end, 11 inner groove wall, 12 outer groove wall,
13 annular groove, 13m groove side bottom, 13n widened part,
14 Protrusion, 15 Opening side groove, 16-19 Arc,
CL Equatorial plane, TG tread ground end.

Claims

A plurality of circumferential grooves formed on the tread surface so as to extend along the tire circumferential direction, and between the circumferential grooves provided on the tire width direction end side of the circumferential grooves and the tread ground contact edge The tire is provided with a circumferential narrow groove that is formed in the land portion of the tire and extends along the tire circumferential direction,
The circumferential narrow groove is
An inner groove wall which is provided on the groove bottom side of the circumferential narrow groove and extends continuously in the tire circumferential direction, the groove width being a groove wall located on the inner side of the circumferential narrow groove in the tire width direction and the tire width direction An annular groove wider than the interval with the outer groove wall which is the groove wall located on the outside;
A protrusion that is provided on the outer groove wall and protrudes toward the inner groove wall, and that is substantially continuous in the tire circumferential direction;
The tire, wherein the protrusion is provided only on the outer groove wall and contacts the inner groove wall when loaded.
In the tire width direction cross section,
The length of the inner groove wall in the tire radial direction is L, and the protrusion depth, which is the distance between the end of the protrusion on the opening side of the circumferential groove and the opening end of the outer groove wall, is H. 2. The tire according to claim 1, wherein the protrusion depth H satisfies a relationship of 0 ≦ H ≦ L / 3.
In the tire width direction cross section,
When the protrusion length, which is the length along the tire radial direction of the protrusion, is K, the protrusion depth H and the protrusion length K satisfy the relationship L / 3 ≦ H + K ≦ L,
The protrusion thickness w is W / 3 ≦ w, where w is the protrusion thickness, which is the protruding dimension of the protrusion from the outer groove wall, and W is the distance between the inner groove wall and the outer groove wall. The tire according to claim 2, wherein a relationship of ≦ 2 W / 3 is satisfied.
The annular groove is
A first arc portion having a radius of curvature R1 of 1.0 to 12.0 mm, the center of curvature being on the inner side in the tire width direction of the inner groove wall and one end connected to the inner groove wall;
The center of curvature is in the annular groove, and the radius of curvature R2 provided between the terminal end of the first arc portion and the innermost end in the tire width direction of the annular groove is 1.5 to 4.0 mm. A second arc portion;
The center of curvature is in the annular groove, and the radius of curvature R3 provided between the innermost end in the tire width direction of the annular groove and the innermost end in the tire radial direction of the annular groove is 1.0 to 16.0 mm. A third arc portion of
The center of curvature is in the annular groove, and the radius of curvature R4 provided between the terminal end of the third arc portion and the outer groove wall and connected to the terminal end of the outer groove wall is 2.0-16. A fourth arc portion of 0.0 mm,
The distance in the tire width direction from the innermost end in the tire width direction of the annular groove to the outer groove wall is 5.7 to 6.5 mm,
4. The tire according to claim 2, wherein an angle θ between the extending direction of the inner groove wall and the tread surface is 60 ° or more and less than 90 °. 5.