JP7001437B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

For competition pneumatic tires such as those for rallies, manual grooves are added to the tread pattern where regulation allows. This manual addition of grooves is referred to in terms such as recut and handcut. As used herein, the term handcut is used.

Non-Patent Document 1 discloses that a pneumatic tire for a rally having a rib-shaped tread pattern is hand-cut in an manner depending on the degree of rainfall and wetness of the road surface.

NEW TYRES PILOT SPORT R-RANGE MICHELIN RALLY ASPHALT 2015, 5 pages, MICHELIN, June 2015, Internet (URL: http://www.michelinmotorsport.com/Tyres/Rally)

Conventional pneumatic tires, including those disclosed in Non-Patent Document 1, have room for improvement in terms of additional workability of grooves by hand cutting.

An object of the present invention is to improve the workability of adding a groove by hand cutting in a pneumatic tire.

In the present invention, the center main groove formed so as to extend in the tire circumferential direction in the central region of the tread portion in the tire width direction, and the tread portion at a position from the in-side ground contact end of the center main groove. The in-side main groove formed so as to extend in the tire circumferential direction, the in-side rib extending in the tire circumferential direction defined by the in-side ground contact end and the in-side main groove, the center main groove and the inn. A center rib extending in the tire circumferential direction defined by the side main groove, an out-side rib extending in the tire circumferential direction defined by the center main groove and the out-side ground contact end, and a tire circumference on the in-side rib. It is provided at intervals in the direction, is defined by a bottom wall and a pair of side walls, both ends in the tire width direction are closed, and a straight line in the tire radial direction toward the in-side main groove side toward the in-side main groove side. A plurality of in-side lateral grooves having a tapered portion that narrows the groove width , which is the distance between the pair of side walls, and the center rib provided at a distance in the tire circumferential direction, the bottom wall and the pair of side walls. The defined, one end in the tire width direction is connected to the in-side main groove, the other end in the tire width direction is closed, and the tire is linear toward the center main groove on the center main groove side in the tire radial direction. Pneumatic including a plurality of center lateral grooves having a tapered portion that narrows the groove width , which is the interval between the pair of side walls, and a plurality of out-side lateral grooves provided on the out-side ribs at intervals in the tire circumferential direction. Provide tires.

When adding a lateral groove connecting the in-side lateral groove and the in-side main groove to the in-side rib by hand cutting, the in-side lateral groove has a tapered portion in which the groove width narrows toward the in-side main groove. Additional lateral grooves can be easily formed along the orientation (tapering orientation). That is, since the in-side lateral groove has a tapered portion, an additional lateral groove extending in the same direction as the in-side lateral groove can be easily formed. Similarly, when adding a lateral groove connecting the center lateral groove and the center main groove to the center rib by hand cutting, the center lateral groove has a tapered portion whose groove width narrows toward the center main groove, so that the same direction as the center lateral groove. Additional lateral grooves can be easily formed. As described above, since the in-side lateral groove and the center lateral groove each have a tapered portion, the workability of adding the groove to the in-side rib and the center rib by hand cutting is improved.

It is preferable that the plurality of out-side lateral grooves have a curved portion whose angle with respect to the tire circumferential direction changes, and the curved portion provided by the plurality of out-side lateral grooves is aligned in the tire width direction.

When a main groove extending in the tire circumferential direction is added on the out-side rib by hand cutting, the main groove is formed so as to pass through the curved portions of the plurality of out-side lateral grooves. Since the curved portion is aligned in the tire width direction, by forming a groove so as to pass through the curved portion, it is possible to easily add a main groove as intended without tilting in the tire circumferential direction. .. That is, by having the bent portion in which the plurality of out-side lateral grooves are aligned, the workability of adding the main groove to the out-side rib by hand cutting is improved.

The in-side lateral groove and the center lateral groove are a first portion located on the in-side and having a first depth, and a second depth located on the out side of the first portion and shallower than the first depth. It is preferable to include the second portion having the above.

The lateral groove connecting the in-side lateral groove and the in-side main groove added by hand cutting is connected to the in-side lateral groove at the second portion having a shallow second depth. Since an additional lateral groove is connected to the inner lateral groove at a shallow depth, it is possible to suppress a decrease in the rigidity of the inner rib due to the provision of the additional lateral groove. Similarly, the additional lateral groove connecting the center lateral groove and the center main groove added by hand cutting is connected to the center lateral groove at the second portion having the shallow second depth, so that the center due to the provision of the additional lateral groove is provided. It is possible to suppress a decrease in the rigidity of the rib.

One of the plurality of in-side lateral grooves and one of the plurality of center-side lateral grooves adjacent to the in-side lateral groove in the tire width direction may be arranged along the same straight line. preferable.

With this configuration, a lateral groove connecting the in-side lateral groove and the in-side main groove is added to the in-side rib by hand cutting, and a lateral groove connecting the center lateral groove and the center main groove is added to the center rib by hand cutting. Side lateral grooves, two additional lateral grooves, and a center lateral groove are arranged along the same straight line. That is, with this configuration, it is possible to form a long lateral groove that reaches the center main groove from the in-side rib by forming an additional lateral groove by hand cutting.

According to the pneumatic tire of the present invention, it is possible to improve the workability of adding a groove by hand cutting.

A partial perspective view of a pneumatic tire according to an embodiment of the present invention. The development view of the tread part of the pneumatic tire of FIG. Enlarged view of a part of FIG. Enlarged view of other parts of FIG. FIG. 3 is a cross-sectional view taken along the line A1-A1 of FIG. FIG. 3 is a cross-sectional view taken along the line A2-A2 of FIG. FIG. 3 is a cross-sectional view taken along the line B1-B1 of FIG. FIG. 3 is a cross-sectional view taken along the line B2-B2 of FIG. FIG. 3 is a cross-sectional view taken along the line B3-B3 of FIG. FIG. 3 is a cross-sectional view taken along the line B4-B4 of FIG. FIG. 3 is a cross-sectional view taken along the line C1-C1 of FIG. FIG. 3 is a cross-sectional view taken along the line C2-C2 of FIG. FIG. 3 is a cross-sectional view taken along the line C3-C3 of FIG. FIG. 3 is a cross-sectional view taken along the line D1-D1 of FIG. FIG. 3 is a cross-sectional view taken along the line D2-D2 of FIG. FIG. 6 is a cross-sectional view taken along the line E1-1 (line F1-F1) of FIG. FIG. 6 is a cross-sectional view taken along the line E2-2 (line F2-F2) of FIG. FIG. 6 is a cross-sectional view taken along the line E3-E3 (line F3-F3) of FIG. The same development view as FIG. 2 which shows an example of the addition of a groove by a hand cut. FIG. 2 is a development similar to FIG. 2 showing another example of adding a groove by hand cutting.

The rubber pneumatic tire (hereinafter referred to as a tire) 1 according to the embodiment of the present invention shown in FIG. 1 is a tire for a rally. The scope of the present invention is not limited to competition tires such as those for rallies. The tire 1 is designated to be mounted on the vehicle. The in-side and out-side in this specified orientation are indicated by "IN" and "OUT" in the figure, respectively.

Referring to FIG. 1, the tire 1 has a pair of sides extending inward in the tire radial direction (conceptually indicated by the arrow RD) from both ends of the tread portion 2 and the tread portion 2 in the tire width direction (conceptually indicated by the arrow WD). A bead portion provided at the innermost end in the tire radial direction of each side portion 3 is provided with the portion 3.

(Overview of rib pattern)
Referring to FIGS. 2 to 4, two tread portions 2 extend continuously in the tire circumferential direction (conceptually indicated by an arrow CD) and make one round of the tread portion 2 in the tire circumferential direction. The main groove, that is, the center main groove 6 and the inner side main groove 7 are formed.

The center main groove 6 is provided on the center (meridian) CE of the tread portion 2 in the tire width direction. The center main groove 6 can be provided in a region (central region) having a certain width in the tire width direction about the center CE. The dimension (width) in the tire width direction of the central region can be set to 0.1 times or more and 0.3 times or less the distance between the in-side ground contact end GEin and the out-side ground contact end GEout (distance in the tire width direction).

With reference to FIG. 5, the center main groove 6 is defined by a bottom wall 6a and a pair of side walls 6b, 6c extending from the bottom wall 6a to the surface of the tread portion 2. The center main groove 6 is a linear groove having a constant groove width GWa1 and has a constant groove depth DEa1. The side walls 6a and 6b of the center main groove 6 have the same inclination angle η1 with respect to the tire radial direction. That is, the side walls 6a and 6b of the center main groove 6 are provided symmetrically with respect to the center of the center main groove 6 in the tire width direction.

The in-side main groove 7 is provided at a position in the tire width direction from the in-side ground contact end GEin with respect to the center main groove 6. With reference to FIG. 6, the in-side main groove 7 is defined by a bottom wall 7a and a pair of side walls 7b, 7c extending from the bottom wall 7a to the surface of the tread portion 2. The in-side main groove 7 is a linear groove having a constant groove width GWa2 and has a constant groove depth DEa2. In the in-side main groove 7, the in-side side wall 7b has an inclination angle η2 with respect to the tire radial direction, and the out-side side wall 7c has an inclination angle η3 with respect to the tire radial direction. The inclination angle η2 of the side wall 7b on the in side is set to be larger than the inclination angle η3 of the side wall 7c on the out side. That is, the side walls 7b and 7c of the in-side main groove 7 are provided asymmetrically with respect to the center of the in-side main groove 7 in the tire width direction.

Three ribs, namely the in-side rib 8, the center rib 9, and the out-side rib 10, are defined by the in-side grounding end GEin, the out-side grounding end GEout, the center main groove 6, and the in-side main groove 7. ..

The in-side grounding end GEin and the in-side main groove 7 define an in-side rib 8 that continuously extends in the tire circumferential direction and makes one round of the tread portion 2 in the tire circumferential direction. The inner rib 8 is linear and has a constant tire width direction dimension (rib width) RWin.

The in-side main groove 7 and the center main groove 6 define a center rib 9 that continuously extends in the tire circumferential direction and makes one round of the tread portion 2 in the tire circumferential direction. The center rib 9 is linear and has a constant rib width RWce.

The center main groove 6 and the out-side ground contact end GEout define an out-side rib 10 that continuously extends in the tire circumferential direction and makes one round of the tread portion 2 in the tire circumferential direction. The out-side rib 10 is linear and has a constant rib width RWout.

In particular, when the tire 1 is mounted on the vehicle so as to have a negative camber, the region on the in side of the tread portion 2 has higher ground contact with the road surface than the region on the out side of the tread portion 2. By providing the in-side main groove 7 at a position from the in-side grounding end GEin to the center main groove 6, the drainage property in the in-side region of the tread portion 2 having high grounding property, particularly the drainage property at the time of braking is improved. can.

The rib width RWin of the in-side rib 8, the rib width RWce of the center rib 9, and the rib width RWout of the out-side rib 10 have the relationship shown in the equation (1).

RWin <RWce <RWout (1)

The rib width RWce of the center rib 9 is wider than the rib width RWin of the in-side rib 8, and the rib width RWout of the out-side rib 10 is wider than the rib width RWce of the center rib 9. That is, the rib width gradually increases from the in-side grounding end GEin toward the out-side grounding end GEout, and the out-side rib 10 has the widest rib width RWout. By setting the rib width, the rigidity of the tread portion 2 gradually increases from the in-side grounding end GEin toward the out-side grounding end GEout, and the cornering performance is improved. Cornering performance includes responsiveness to steering, steering stability during cornering, steering angle stability during cornering, and ease of steering recovery in the event of slippage during cornering.

As described above, in the in-side main groove 7, the inclination angle η3 of the side wall 7b on the in side is larger than the inclination angle η2 of the side wall 7c on the out side. Of the in-side rib 8, center rib 9, and out-side rib 10, the in-side rib 8 has the narrowest rib width RWin. By setting a large inclination angle of the inner side wall 7b of the inner side main groove 7 defining the inner side rib 8 together with the inner side grounding end GEin, a narrow rib width RWin is provided particularly with respect to a load in the tire width direction. The rigidity of the inner rib 8 can be increased.

In the present embodiment, as described above, the cross-sectional shape of the in-side main groove 7 is asymmetric, and the cross-sectional shape of the center main groove 6 is symmetrical. However, the cross-sectional shapes of both the in-side main groove 7 and the center main groove 6 may be asymmetric. Further, for example, when the rigidity of the inner rib 8 can be ensured, the cross-sectional shape of the inner main groove 7 may be symmetrical and the cross-sectional shape of the center main groove 6 may be symmetrical or asymmetric.

(Inside rib)
Referring to FIGS. 2 and 3, a plurality of first-in-side lateral grooves 11 and a plurality of second-in-side lateral grooves 12 are alternately provided on the in-side ribs 8 at regular intervals in the tire circumferential direction. Has been done.

Referring together with FIGS. 7A to 7D, the first inner lateral groove 11 is defined by a bottom wall 11a and a pair of side walls 11b, 11c extending from the bottom wall 11a to the surface of the tread portion 2. The side walls 11b and 11c of the first inner side lateral groove 11 have the same inclination angle η3 with respect to the tire radial direction. That is, the side walls 11b and 11c of the first-in side lateral groove 11 are provided symmetrically.

Referring together with FIGS. 8A to 8C, the second inner lateral groove 12 is defined by a bottom wall 12a and a pair of side walls 12b, 12c extending from the bottom wall 12a to the surface of the tread portion 2. The pair of side walls 12b, 12c of the second inner side lateral groove 12 have the same inclination angle η4 with respect to the tire radial direction. That is, the pair of side walls 12b and 12c of the second inner side lateral groove 12 are provided symmetrically. In the present embodiment, the inclination angle η4 of the side walls 12b and 12c of the second in-side lateral groove 12 is set to be the same as the inclination angle η3 of the side walls 11b and 11c of the first in-side lateral groove 11.

With reference to FIGS. 2 and 3, the shapes of the first in-side lateral groove 11 and the second in-side lateral groove 12 in the tire radial direction will be described.

The first in-side lateral groove 11 extends upward to the right from the in-side to the out-side so as to form an inclination angle θ1 with respect to the tire circumferential direction as a whole. The first in-side lateral groove 11 includes a reverse taper portion 11e in which the groove width GWb (see FIGS. 7A to 7B) widens from the in-side end portion 11d toward the out side. Further, the first in-side lateral groove 11 includes a tapered portion 11f in which the groove width GWb narrows from the out-side end of the reverse tapered portion 11e toward the out-side, that is, toward the in-side main groove 7. The in-side end portion 11d of the first in-side lateral groove 11 is located on the in-side side of the in-side grounding end GEin. That is, the first in-side lateral groove 11 extends from the inside of the in-side rib 8 beyond the in-side grounding end GEin. This configuration also improves drainage. The out-side end portion 11g of the first in-side lateral groove 11 is terminated in the in-side rib 8 without reaching the in-side main groove 7.

The second in-side lateral groove 12 extends upward to the right from the in-side to the out-side so as to form an inclination angle θ2 with respect to the tire circumferential direction as a whole, and this inclination angle θ2 is the inclination angle θ2 of the first in-side lateral groove 11. It is the same as the inclination angle θ1. Further, the shape of the second in-side lateral groove 12 in the tire radial direction is the same as that of the first in-side lateral groove 11. That is, the second in-side lateral groove 12 includes the reverse tapered portion 12e and the tapered portion 12f in order from the in-side to the out-side. Further, the in-side end portion 12d of the second in-side lateral groove 12 is located on the in-side side of the in-side grounding end GEin, and the out-side end portion 12g is inside the in-side rib 8 without reaching the in-side main groove 7. It ends with.
The drainage property is also improved because the second in-side lateral groove 12 extends from the inside of the in-side rib 8 beyond the in-side grounding end GEin. The length of the second-in side lateral groove 12 is shorter than the length of the first-in side lateral groove 11.

As shown by line L1 in FIG. 2, the out-side end 11g of all the first in-side lateral grooves 11 and the out-side end 12g of all the second in-side lateral grooves 12 are located in the tire width direction. It is matched. Therefore, the region on the out side of the rib 8 on the in side, that is, the region in the tire width direction defined by the line L1 and the main groove 7 on the in side is the plain region 8a. Here, the "plain area" refers to an area in which a concave structure such as a groove, a sipe, or a dimple is not provided and can be regarded as having substantially no unevenness. This point is the same for the plain region 9a of the center rib 9 and the plain region 10a of the out-side rib 10, which will be described later. By providing the plain region 8a in the region on the out side in the tire width direction, the rib 8 on the in side has a relatively higher rigidity in the region on the out side than the rigidity in the region on the in side. As a result, the cornering performance is further improved.

The groove depth of the first-in side lateral groove 11 will be described with reference to FIGS. 3 and 7A to 7C. The first in-side lateral groove 11 has an in-side portion 11h, an intermediate portion (first portion) 11i, and an out-side portion (second portion) 11j arranged from the in-side to the out-side and having different depths. Have. The in-side portion 11h is provided so as to straddle the in-side ground contact end GEin, and includes an in-side region of the reverse taper portion 11e in the shape in the tire radial direction. The intermediate portion 11i includes a region on the out side of the reverse taper portion 11e in the shape in the tire radial direction. The out-side portion 11j includes the most out-side region of the reverse tapered portion 11e and the tapered portion 11f in the shape in the tire radial direction. In the first in-side lateral groove 11, the depth (second depth) DEb1 of the out-side portion 11j is shallower than the depth (first depth) DEb2 of the intermediate portion 11i, and is shallower than the depth DEb2 of the intermediate portion 11i. The depth DEb3 of the inner side portion 11h is shallow.

Referring to FIGS. 3 and 8A to 8C, the second in-side lateral groove 12 is arranged from the in-side to the out-side in the same manner as the first in-side lateral groove 11, and has different depths. It has a portion 12h, an intermediate portion (first portion) 12i, and an out-side portion (second portion) 12j. The in-side portion 12h is provided so as to straddle the in-side ground contact end GEin, and includes an in-side region of the reverse taper portion 12e in the shape in the tire radial direction. The intermediate portion 12i includes a region on the out side of the reverse taper portion 12e in the shape in the tire radial direction. The out-side portion 12j includes the most out-side region of the reverse tapered portion 12e and the tapered portion 12f in the shape in the tire radial direction. In the first in-side lateral groove 11, the groove depth (second depth) DEc1 of the out-side portion 12j is shallower than the groove depth (first depth) DEc2 of the intermediate portion 12i, and the depth DEc2 of the intermediate portion 12i. The depth DEc3 of the inner side portion 12h is shallower than that.

Referring to FIG. 7D, the first in-side lateral groove 11 has a curved bottom wall 11a at a portion 11k connecting an intermediate portion 11i having a deep groove depth DEb2 and an out-side portion 11j having a shallow groove depth DEb1. It is supposed to be. Similarly, referring to FIG. 8C, the first in-side lateral groove 11 is a bottom wall 12a at a portion 12k connecting an intermediate portion 12i having a deep groove depth DEc2 and an out-side portion 12j having a shallow groove depth DEc1. Is curved. By making the bottom walls 11a and 12a curved in the portions 11k and 12k, stress concentration on the bottom walls 11a and 12a in the portions 11k and 12k can be avoided or relaxed. As a result, it is possible to secure the required rigidity of the portion of the in-side rib 8 provided with the first in-side lateral groove 11 and the second in-side lateral groove 12.

(Center rib)
Referring to FIGS. 2 and 3, the center rib 9 is provided with a plurality of center lateral grooves 13 at regular intervals in the tire circumferential direction.

Referring to FIGS. 9A and 9B, the center lateral groove 13 is defined by a bottom wall 13a and a pair of side walls 13b, 13c extending from the bottom wall 13a to the surface of the tread portion 2. The pair of side walls 13b and 13c of the center lateral groove 13 have the same inclination angle η5 with respect to the tire radial direction. That is, the pair of side walls 13b and 13c of the center lateral groove 13 are provided symmetrically.

The shape of the center lateral groove 13 in the tire radial direction will be described with reference to FIGS. 2 and 3.

The center lateral groove 13 extends upward to the right from the in side to the out side so as to form an inclination angle θ3 with respect to the tire circumferential direction as a whole. The center lateral groove 13 is composed of a tapered portion 13d in which the groove width GWd (see FIG. 10A) narrows from the in-side end to the out-side end, that is, toward the center main groove 6. The in-side end portion 13e of the center lateral groove 13 is connected to the in-side main groove 7. The end portion 13f on the out side of the center lateral groove 13 is terminated in the center rib 9 without reaching the center main groove 6.

As shown by the line L2 in FIG. 2, the inner end portions 13e of all the center lateral grooves 13 are aligned in the tire width direction. Therefore, the region on the out side of the center rib 9, that is, the region in the tire width direction defined by the line L2 and the center main groove 6, is the plain region 9a. By providing the plain region 9a in the region on the out side in the tire width direction, the center rib 9 has a relatively higher rigidity in the region on the out side than the rigidity in the region on the in side. As a result, the cornering performance is further improved.

The groove depth of the center lateral groove 13 will be described with reference to FIGS. 9A and 9B. The center lateral groove 13 has an in-side portion (first portion) 13g and an out-side portion (second portion) 13h having different depths, which are arranged from the in-side to the out-side. The inner side portion 13g includes the inner side end portion 13e in the shape in the tire radial direction. The out-side portion 13h includes an out-side end portion 13f in the shape in the tire radial direction. In the center lateral groove 13, the depth (second depth) DEd1 of the out-side portion 13h is shallower than the depth (first depth) DEd2 of the in-side portion 13g.

Referring to FIG. 9B, the center lateral groove 13 has a curved bottom wall 13a at a portion 13i connecting an in-side portion 13g having a deep groove depth DEd2 and an out-side portion 13h having a shallow groove depth DEd1. .. By making the bottom wall 13a curved in the portion 13i, stress concentration on the bottom wall 13a in the portion 13i can be avoided or alleviated. As a result, the required rigidity of the portion of the center rib 9 provided with the center lateral groove 13 can be secured.

As conceptually shown by lines L3 and L4 in FIG. 2, each center lateral groove 13 is arranged on an extension line of the first in-side lateral groove 11 or the second in-side lateral groove 12.

(Rib on the out side)
Referring to FIGS. 2 and 4, a plurality of first out-side lateral grooves 14 and a plurality of second out-side lateral grooves 15 are alternately provided on the out-side ribs 10 at regular intervals in the tire circumferential direction. Has been done. The shapes of the first out-side lateral groove 14 and the second out-side lateral groove 15 in the tire radial direction are both polygonal lines.

Referring to FIGS. 10A to 10C, the first out-side lateral groove 14 is defined by a bottom wall 14a and a pair of side walls 14b, 14c extending from the bottom wall 14a to the surface of the tread portion 2. Further, the second out-side lateral groove 15 is defined by a bottom wall 15a and a pair of side walls 15b and 15c extending from the bottom wall 15a to the surface of the tread portion 2. The pair of side walls 14b, 14c of the first out-side lateral groove 14 have the same inclination angle η6 with respect to the tire radial direction. Further, the pair of side walls 15b and 15c of the second out-side lateral groove 15 have the same inclination angle η7 with respect to the tire radial direction. That is, the side walls 14b and 14c of the first out-side lateral groove 14 and the side walls 15b and 15c of the second out-side lateral groove 15 are both provided symmetrically. In the present embodiment, the inclination angles η6 of the side walls 14b and 14c of the first out-side lateral groove 14 and the inclination angles η7 of the side walls 15b and 15c of the second out-side lateral groove 15 are set to be the same.

With reference to FIGS. 2 and 4, the shapes of the first out-side lateral groove 14 and the second out-side lateral groove 15 in the tire radial direction will be described.

The first out-side lateral groove 14 extends upward to the right from the in-side to the out-side as a whole. The first out-side lateral groove 14 is narrow from the in-side to the out-side, including a reverse tapered portion 14e including an in-side end portion 14d, a bent portion 14f, a wide width portion 14g, a tapered portion 14h, and an out-side end portion 14i. A width portion 14j is provided. The reverse taper portion 14e extends upward to the right from the in side to the out side so as to form an inclination angle θ4 with respect to the tire circumferential direction. The wide portion 14g, the tapered portion 14h, and the narrow portion 14i extend upward to the right from the in side to the out side so as to form an inclination angle θ5 larger than the inclination angle θ4 with respect to the tire circumferential direction. The inclination angle of the first out-side lateral groove 14 at the bent portion 14f with respect to the tire circumferential direction is changed.

In the reverse taper portion 14e, the groove width GWe (see FIGS. 10A to 10C) widens from the in side to the out side. The out-side end of the reverse taper portion 14e and the in-side end of the wide portion 14g are connected by a curved portion 14f. The groove width GWe is substantially constant in the bent portion 14f and the wide portion 14g. The out-side end of the wide portion 14g and the in-side end of the tapered portion 14e are connected. In the tapered portion 14h, the groove width GWe is narrowed from the in side to the out side. The out-side end of the tapered portion 14h and the in-side end of the narrow width portion 14j are connected. The groove width GWe in the narrow width portion 14j is substantially constant, and is sufficiently narrower than the groove width GWe in the wide width portion 14g.

The shape of the second out-side lateral groove 15 in a plan view is the same except that the length of the second out-side lateral groove 15 is shorter than the length of the first out-side lateral groove 14.

The second out-side lateral groove 15 extends upward to the right from the in-side to the out-side as a whole. The second out-side lateral groove 15 is narrow from the in-side to the out-side, including a reverse tapered portion 15e including an in-side end portion 15d, a bent portion 15f, a wide width portion 15g, a tapered portion 15h, and an out-side end portion 15i. A width portion 15j is provided. The reverse taper portion 15e extends upward to the right from the in side to the out side so as to form an inclination angle θ6 with respect to the tire circumferential direction. The wide portion 15g, the tapered portion 15h, and the narrow portion 15i extend upward to the right from the in side to the out side so as to form an inclination angle θ7 larger than the inclination angle θ6 with respect to the tire circumferential direction. The inclination angle of the second out-side lateral groove 15 with respect to the tire circumferential direction is changed at the bent portion 15f. The bent portions 15f of all the second out-side lateral grooves 15 and the bent portions 14f of all the first out-side lateral grooves 14 are aligned in the tire width direction, and these bent portions 14f and 15f are approximately tire circumferences. It is arranged on a straight line extending in the direction.

In the reverse taper portion 15e, the groove width GWf (see FIGS. 10A to 10C) widens from the in side to the out side. The out-side end of the reverse taper portion 15e and the in-side end of the wide portion 15g are connected by a curved portion 15f. The groove width GWf is substantially constant in the bent portion 15f and the wide portion 15g. The out-side end of the wide portion 15g and the in-side end of the tapered portion 15h are connected. In the tapered portion 15h, the groove width GWf narrows from the in side to the out side. The out-side end of the tapered portion 15h and the in-side end of the narrow width portion 15j are connected. The groove width GWf in the narrow width portion 15j is substantially constant, and is sufficiently narrower than the groove width GWf in the wide width portion 15g.

Both ends of the first out-side lateral groove 14 and the second out-side lateral groove 15 are closed in the out-side rib 10. That is, the ends 14d and 14i of the first out-side lateral groove 14 are both located in the out-side rib 10, and the ends 15d and 15i of the second out-side lateral groove 15 are both located in the out-side rib 10. There is.

As shown by line L5 in FIG. 2, the out-side end 14i of all the first out-side lateral grooves 14 and the out-side end 15i of all the second out-side lateral grooves 15 are located in the tire width direction. It is matched. Therefore, the out-side region of the out-side rib 10, that is, the region in the tire width direction defined by the line L5 and the outer ground contact end GEout is the plain region 10a. By providing the plain region 10a in the region on the out side in the tire width direction, the rib 10 on the out side has a relatively higher rigidity in the region on the out side than the rigidity in the region on the in side. As a result, the cornering performance is further improved.

The first and second out-side lateral grooves 14 and 15 are both polygonal lines having curved portions 14f and 15f. By forming the first and second out-side lateral grooves 14 and 15 into a polygonal line, the rigidity of the out-side rib 10 can be increased particularly with respect to the load in the tire width direction, and the cornering performance is further improved.

As described above, the out-side ribs 10 are provided with first out-side lateral grooves 14 and second out-side lateral grooves 15 having different lengths alternately in the tire circumferential direction. Therefore, in particular, the rigidity of the out-side rib with respect to the load in the tire width direction can be increased, and the cornering performance is further improved.

The groove depth of the first out-side lateral groove 14 will be described with reference to FIGS. 4 and 10A to 10C. The first out-side lateral groove 14 has a main body portion (first portion) 14k and an out-side portion (second portion) 14m arranged from the in side to the out side and having different depths. The main body portion 14k includes a reverse tapered portion 14e, a bent portion 14f, a wide width portion 14g, and a tapered portion 14h in the shape in the tire radial direction. The out-side portion 14m includes a narrow portion 15j in the shape in the tire radial direction. In the first out-side lateral groove 14, the depth (second depth) DEb2 of the out-side portion 14 m is shallower than the depth (first depth) DEb1 of the main body portion 14k.

With reference to FIGS. 4 and 10A to 10C, the second out-side lateral groove 15 is a main body portion having different depths arranged from the in-side to the out-side, similarly to the first out-side lateral groove 14. It has a first part) 15k and an out side part (second part) 15m. The main body portion 15k includes a reverse tapered portion 15e, a bent portion 15f, a wide width portion 15g, and a tapered portion 15h among the shapes in the tire radial direction. The out-side portion 15m includes a narrow portion 15j in the shape in the tire radial direction. In the first out-side lateral groove 14, the depth (second depth) DEf2 of the out-side portion 15 m is shallower than the depth (first depth) DEf1 of the main body portion 15k.

The first out-side lateral groove 14 has a curved bottom wall 14a at a portion 14n connecting a main body portion 14k having a deep groove depth DEe2 and an out-side portion 14m having a shallow groove depth DEe1. Similarly, the second out-side lateral groove 15 has a curved bottom wall 15a at a portion 15n connecting a main body portion 15k having a deep groove depth DEf2 and an out-side portion 15m having a shallow groove depth DEf2. By making the bottom walls 14a and 15a curved in the portions 14n and 15n, stress concentration on the bottom walls 14a and 15a in the portions 14n and 15n can be avoided or alleviated. As a result, it is possible to secure the required rigidity of the portion of the out-side rib 10 provided with the first out-side lateral groove 14 and the second out-side lateral groove 15.

As described above, the in-side rib 8, the center rib 9, and the out-side rib 10 have plain regions 8a, 9a, and 10a on the out side in the tire width direction, respectively. By providing the plain regions 8a, 9a, and 10a in the out-side region in the tire width direction, the in-side rib 8, the center rib 9, and the out-side rib 10 are all in the in-side region in the tire width direction. The rigidity of the region on the out side is relatively higher than the rigidity. As a result, the cornering performance is further improved.

Referring to FIG. 2, the dimension of the plain region 8a of the in-side rib 8 in the tire width direction (plain region width) SLWin, the dimension of the center rib 9 of the plain region 9a in the tire width direction (plain region width) SLWce, and the out The dimension (plain area width) SLWout of the plain area 10a of the side rib 10 in the tire width direction is set so as to satisfy the relationship of the following equation (2).

SLWin <SLWce <SLWout (2)

The plain area width SLWce of the center rib 9 is wider than the plain area width SLWin of the in-side rib 8, the plain area width SLWout of the out-side rib 10 is wider than the plain area width SLWout of the center rib 9, and the out-side rib 10 is the most. It has a wide plain area width. The setting of the plain region widths SLWin, SLWce, and SLWout also functions so that the rigidity of the tread portion 2 gradually increases from the in-side grounding end GEin toward the out-side grounding end GEout, so that the cornering performance is further improved.

As described above, in the in-side rib 8, the groove depth DEb2 of the out-side portion 11j of the first in-side lateral groove 11 is shallower than the groove depth DEb1 of the intermediate portion 11i of the first in-side lateral groove 11, and the second The groove depth DEc2 of the out-side portion 12j of the second in-side lateral groove 12 is shallower than the groove depth DEc1 of the intermediate portion 12i of the in-side lateral groove 12. Further, in the center rib 9, the groove depth DEd2 of the out-side portion 13h of the center lateral groove 13 is shallower than the groove depth DEd1 of the in-side portion 13g of the center lateral groove 13. Further, in the out-side rib 10, the groove depth DEe2 of the out-side portion 14m of the first out-side lateral groove 14 is shallower than the groove depth DEe1 of the main body portion 14k of the first out-side lateral groove 14, and the second out-side lateral groove The groove depth DEf2 of the out-side portion 15m of the second out-side lateral groove 15 is shallower than the groove depth DEf1 of the main body portion 15k of the main body 15. The groove depths of the first and second in-side lateral grooves 11 and 12, the center lateral groove 13, and the first and second out-side lateral grooves 14 and 15 are set for the in-side rib 8, the center rib 9, and the out. Each of the side ribs 10 functions to have higher rigidity on the out side than on the in side. The cornering performance of the in-side rib 8, the center rib 9, and the out-side rib 10 is further improved by increasing the rigidity on the out side rather than the in side.

Next, the addition of a groove by hand cutting to the tire 1 will be described.

11 and 12 show tire 1 with grooves added by hand cutting. FIG. 11 shows an example in which the degree of rainfall or the wetness of the road surface is relatively light. FIG. 12 shows an example in which the degree of rainfall or the wetness of the road surface is relatively severe.

In the example of FIG. 11, lateral grooves 51A and 52 are added to the inner side rib 8 and the center rib 9 by hand cutting, respectively. No groove is added to the out-side rib 10.

In the in-side rib 8, a linear groove 51A extending diagonally connecting the out-side end portion 11g of the first in-side lateral groove 11 and the in-side main groove 7 is added. No groove is added between the second inner side lateral groove 12 and the inner side main groove 7. Therefore, when the first-in-side lateral groove 11 and the second-in-side lateral groove 12 are regarded as the same lateral groove, every other lateral groove 51A is added to such a plurality of lateral grooves.

In the center rib 9, a linear lateral groove 52 extending diagonally connecting the end portion 13f on the out side of the center lateral groove 13 and the center main groove 6 is added. Specifically, every other lateral groove 52 is added to the plurality of center lateral grooves 13.

In the example of FIG. 12, lateral grooves 51A, 51B, and 52 are added to the inner rib 8 and the center rib 9 by hand cut, respectively, and the main groove 53 is added to the out side rib 10 by hand cut, respectively.

In the in-side rib 8, a linear groove 51A extending diagonally connecting the out-side end portion 11g of the first in-side lateral groove 11 and the in-side main groove 7 is added. Further, a linear groove 51B extending diagonally connecting the out-side end portion 12g of the second in-side lateral groove 12 and the in-side main groove 7 is added. Therefore, when the first-in-side lateral groove 11 and the second-in-side lateral groove 12 are regarded as the same lateral groove, the lateral grooves 51A and 51B are added to all of such a plurality of lateral grooves.

In the center rib 9, every other center lateral groove 13 has a linear lateral groove 52 extending diagonally connecting the end portion 13f on the out side of the center lateral groove 13 and the center main groove 6. ..

In the out-side rib 10, the tread portion 2 goes around the tread portion 2 once in the tire circumferential direction so as to pass through the bent portion 14 g of the first out-side lateral groove 14 and the bent portion 15f of the second out-side lateral groove 15. A main groove 52 has been added.

As described above, the first in-side lateral groove 11 and the second in-side lateral groove 12 of the in-side rib 8 have groove widths GWb, GWc (FIGS. 7A to 7C, FIGS. 8A, and FIGS. (See 8B) is provided with tapered portions 11f and 12f that narrow. When the lateral grooves 51A and 51B are added to the in-side rib 8 by hand cutting, the additional lateral grooves 51A and 51B can be easily formed along the direction (tapering direction) of the tapered portions 11f and 12f. That is, since the first and second inner lateral grooves 11 and 12 have tapered portions 11f and 12f, additional lateral grooves 51A and 51B extending in the same direction can be easily formed.

As described above, the center lateral groove 13 of the center rib 9 is composed of a tapered portion 13d whose groove width GWd (see FIG. 9A) narrows toward the center main groove 6. When the lateral groove 52 is added to the center rib 9 by hand cutting, the additional lateral groove 52 can be easily formed along the direction of the tapered portion 13d. That is, since the center lateral groove 13 has the tapered portion 13d, an additional lateral groove 52 extending in the same direction can be easily formed.

As described above, since the in-side lateral grooves 11 and 12 and the center lateral grooves 13 have tapered portions 11f, 12f and 13d, respectively, the workability of adding grooves to the in-side ribs 8 and center ribs 9 by hand cutting is improved. do.

As described above, the bent portion 14f of the first out-side lateral groove 14 and the bent portion 15f of the second out-side lateral groove 15 are aligned in the tire width direction. When the main groove 53 is added to the out-side rib 10 by hand cutting, the main groove 53 is formed so as to pass through the aligned bending portions 14f and 15f so that the main groove 53 does not have an inclination in the tire circumferential direction, as intended. The main groove 53 can be easily added. That is, by having the bent portions 14f and 15f in which the first and second out-side lateral grooves 14 and 15 are aligned, the workability of adding the main groove to the out-side rib 10 by hand cutting is improved.

As described above, the in-side lateral grooves 11 and 12 include out-side portions 11j and 12j having shallow depths DEb1 and DEc1 (see FIGS. 7A and 8A) located on the out-side. The lateral grooves 51A and 51B added by hand cutting are connected to the in-side lateral grooves 11 and 12 at the out-side portions 11j and 12j. Since the additional lateral grooves 51A and 51B are connected to the inner lateral grooves 11 and 12 at the shallow out portions 11j and 12j, the rigidity of the inner rib 8 due to the provision of the additional lateral grooves 51A and 51B is reduced. It can be suppressed.

As described above, the center lateral groove 13 includes an out-side portion 13h having a shallow depth DEc1 (see FIG. 8A) located on the out-side. Since the lateral groove 52 added by hand cutting is connected to the center lateral groove 13 at the out side portion 13h, it is possible to suppress a decrease in the rigidity of the center rib 10 due to the provision of the additional lateral groove 52.

As described above, the individual center lateral grooves 13 are arranged on the extension line of the first in-side lateral groove 11 or the second in-side lateral groove 12 (see lines L3 and L4 in FIG. 2). Therefore, in the case of the example of FIG. 12, the lateral grooves 51B and 52 added by hand cutting are substantially arranged on one straight line. Therefore, by adding the lateral grooves 51B and 52 by hand cutting, a long lateral groove (second inner lateral groove 12, added lateral groove 51B, center lateral groove 9, and added lateral groove 52) is formed from the in-side rib 8 to the center main groove 6. Will be done.

As described above, the tire 1 according to the present embodiment can improve the cornering performance while ensuring the drainage property, and is excellent in the workability of adding the groove by hand cutting.

1 Pneumatic tire 2 Tread part 3 Side part 4 Bead part 6 Center main groove 6a Bottom wall 6b, 6c Side wall 7 Inn side main groove 7a Bottom wall 7b, 7c Side wall 8 Inn side rib 8a Plain area 9 Center rib 9a Plain area 10 Out side rib 10a Plain area 11 1st in side lateral groove 11a Bottom wall 11b, 11c Side wall 11d, 11g End part 11e Reverse taper part 11f Tapered part 11h In side part 11i Intermediate part (1st part)
11j Out side part (second part)
11k part 12 2nd in side lateral groove 12a bottom wall 12b, 12c side wall 12e reverse taper part 12f taper part 12h in side part 12i middle part (1st part)
12j Out side part (second part)
12k part 13 Center lateral groove 13a Bottom wall 13b, 13c Side wall 13d Tapered part 13e, 13f End part 13g Inn side part (first part)
13h Out side part (second part)
13i part 14 1st out side lateral groove 14a bottom wall 14b, 14c side wall 14d, 14i end part 14e reverse taper part 14f bent part 14g wide part 14h taper part 14j narrow part 14k main body part (first part)
14m out side part (second part)
14n part 15 2nd out side lateral groove 15a bottom wall 15b, 15c side wall 15d, 15i end part 15e reverse taper part 15f bent part 15g wide part 15h taper part 15j narrow part 15k main body part (first part)
15m out side part (second part)
15n partial WD tire width direction RD tire radial direction CE center line GEin in side grounding end GEout out side grounding end GWa1, GWa2, GWb, GWc, GWd, GWe, GWf groove width DEa1, DEa2, DEb1, DEb2, DEb3, DEc1, DEc2, DEc3, DEd1, DEd2, DEe1, DEe2, DEf1, DEf2 Groove depth RWin, RWce, RWout Rib width RWin, RWce, RWout Plain area width θ1, θ2, θ3, θ4, θ5, θ6, θ7 η1, η2, η3, η4, η5, η6, η7 Side wall tilt angle

Claims (4)

In the central region of the tread portion in the tire width direction, a center main groove formed so as to extend in the tire circumferential direction,
An in-side main groove formed so as to extend in the tire circumferential direction at a position of the tread portion from the in-side ground contact end with respect to the center main groove,
An in-side rib extending in the tire circumferential direction defined by the in-side ground contact end and the in-side main groove,
A center rib extending in the tire circumferential direction defined by the center main groove and the in-side main groove,
The out-side ribs extending in the tire circumferential direction, defined by the center main groove and the out-side ground contact end ,
The in-side ribs are provided at intervals in the tire circumferential direction, are defined by a bottom wall and a pair of side walls, both ends in the tire width direction are closed, and the in-side main groove side faces the in-side main groove. A plurality of in-side lateral grooves having a tapered portion that narrows the groove width , which is the distance between the pair of side walls that are linear in the tire radial direction .
The center rib is provided at intervals in the tire circumferential direction, is defined by a bottom wall and a pair of side walls, one end in the tire width direction is connected to the inner main groove, and the other end in the tire width direction is closed. A plurality of center lateral grooves having a tapered portion that narrows the groove width , which is the distance between the pair of side walls that are linear in the tire radial direction toward the center main groove on the center main groove side.
A pneumatic tire provided with a plurality of out-side lateral grooves provided on the out-side ribs at intervals in the tire circumferential direction. The plurality of out-side lateral grooves are provided with bends whose angle with respect to the tire circumferential direction changes.
The pneumatic tire according to claim 1, wherein the curved portion provided by the plurality of out-side lateral grooves is aligned in the tire width direction. The in-side lateral groove and the center lateral groove are a first portion located on the in-side and having a first depth, and a second depth located on the out side of the first portion and shallower than the first depth. The pneumatic tire according to claim 1 or 2, respectively, comprising a second portion having. A claim that one of the plurality of in-side lateral grooves and one of the plurality of center-side lateral grooves adjacent to the in-side lateral groove in the tire width direction are arranged along the same straight line. The pneumatic tire according to any one of Items 1 to 3.

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