JP6018902B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  2. Description of the Related Art Conventionally, as a pneumatic tire, a tire in which a protrusion forming area in which a lattice-like protrusion is formed on a groove surface constituting a main groove is known (see, for example, Patent Document 1).

However, in the conventional pneumatic tire, a protrusion is also formed on the groove bottom surface of the groove surface. For this reason, there exists a problem that the drainage property in a main groove is impaired.
In addition, groove cracks are likely to occur at the boundary between the groove and the bottom of the groove. However, in the conventional pneumatic tire, no consideration is given to the occurrence of such groove cracks.

JP-A-10-76810

  The subject of this invention is setting it as the structure excellent in the groove crack resistance of a groove bottom, maintaining drainage performance.

As a means for solving the above problems, the present invention provides:
A pneumatic tire having a block obtained by forming a main groove and a lateral groove on a tread surface,
A ridge that is displaced continuously or substantially continuously along the side surface of the block and that reverses the displacement direction at a plurality of locations is formed.

  With this configuration, the block can be sufficiently reinforced by the protrusions formed on the side surfaces. In addition, since the protrusions are continuous or substantially continuous and reverse the displacement direction, distortion does not concentrate at the base of the block, that is, at the boundary between the block and the groove bottom during traveling. Therefore, a groove crack or the like is hardly generated at the boundary portion. Further, the protrusion is not only formed on the groove bottom, but is not formed on the entire groove wall. Therefore, since the groove volume as a whole is not reduced so much, the drainage performance can be sufficiently exhibited.

  The protrusion is preferably formed in a sawtooth shape.

  With this configuration, the strain generated at the boundary between the block and the groove bottom can be reduced and dispersed at the same time, so that the groove crack resistance can be improved.

  It is preferable that the protrusion is formed from a corner on the groove bottom side of the block.

  With this configuration, it is possible to reinforce the portion where groove cracks are most likely to occur and to further improve the groove crack resistance.

  It is preferable to form an auxiliary protrusion that intersects the protrusion.

  With this configuration, it is possible to further improve the groove crack resistance as compared with a configuration in which a continuous or substantially continuous protrusion is provided.

  It is preferable to form an arched ridge on the side surface of the block.

  With this configuration, it is possible to disperse the force acting on the ridges arranged on the groove wall by the arch-shaped ridges, exhibit the reinforcing effect of the block, and further improve the groove crack resistance of the groove bottom It becomes possible.

  According to the present invention, the protrusion is formed so as to be continuously or substantially continuously displaced along the side surface of the block, so that the deformation of the block is suppressed and the distortion to the boundary portion between the block and the groove bottom is suppressed. Can be prevented. For this reason, it becomes possible to prevent the occurrence of groove cracks at this boundary portion and to improve the groove crack resistance. Further, the protruding portion is not only formed on the groove bottom, but is not formed on the entire groove wall. Therefore, since the groove volume is not reduced as much as a whole, the drainage performance can be sufficiently exhibited.

It is a fragmentary top view of the tread surface of the pneumatic tire concerning this embodiment. It is a perspective view which shows a part of tread surface of FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is a fragmentary sectional view of FIG. It is a side view of 1 block of FIG. It is a side view of the block concerning other embodiments. It is a side view of the block concerning other embodiments. It is a side view of the block concerning other embodiments.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a partial plan view of a tread surface 1 of a tire according to this embodiment, and FIG. 2 shows a part of the tread surface 1. On the tread surface 1, main grooves 2 extending in the circumferential direction are formed in a plurality of rows in the width direction. A plurality of lateral grooves 3 intersecting the main groove 2 are formed on the tread surface 1. Here, the lateral grooves 3 are inclined in the same direction (here, orthogonal) with respect to the main grooves 2 and are provided at intervals in the circumferential direction. A plurality of blocks 4 are formed on the tread surface 1 by the main grooves 2 and the lateral grooves 3.

  A first protrusion 5 and a second protrusion 6 are formed on the side surface of each block 4. 2 and 3, the first protrusion 5 and the second protrusion 6 are formed on the side surface 4 a of the block 4 on the main groove 2 side.

  As shown in FIG. 3 and FIG. 5, the first protrusion 5 rises from a corner 7 where the main groove 2 and the lateral groove 3 intersect, and after going diagonally upward, it turns back and goes diagonally downward. The peak portion 8 is formed by reaching the groove bottom 2a. Then, a plurality (three in this case) of the chevron portions 8 are provided continuously in the circumferential direction of the main groove 2 to form a sawtooth shape. As shown in FIG. 4, the base of the block 4 is formed in an arc shape and gradually becomes horizontal toward the groove bottom 2 a of the main groove 2. The first protrusion 5 is formed up to the boundary with the groove bottom 2a, but the protruding dimension gradually decreases along the arc surface.

  As shown in FIG. 5, the second protrusion 6 is formed in an arch shape with a radius of curvature R that connects the apexes 9 at the center of the chevron 8.

Each dimension of the 1st protrusion part 5 and the 2nd protrusion part 6 is determined as follows.
That is, the projecting dimension a (see FIG. 4) from the side surfaces of the first and second ridges 5 and 6 is determined so as to satisfy the following expression (1).
T / 20 ≦ a ≦ T / 5 (1)
T: width dimension of main groove 2

Moreover, the width dimension b (refer FIG. 5) of the 1st protrusion part 5 and the 2nd protrusion part 6 is determined so that following Formula (2) may be satisfied.
H / 40 ≦ b ≦ H / 5 (2)
H: Depth dimension of main groove 2 (height dimension of block 4)

Moreover, the formation range (distance from the groove bottom 2a of the main groove 2) h (refer FIG. 5) in the block 4 of the 2nd protrusion part 6 is determined so that following Formula (3) may be satisfied.
H / 4 ≦ h ≦ H (3)

Furthermore, the distance l (see FIG. 5) from the straight line connecting the top points of the second protrusions 6 of the apex 9 of the three mountain-shaped portions 8 located in the center is expressed by the following equation (4). It has been decided to satisfy.
0 ≦ l ≦ h / 4 (4)

  The second protrusion 6 is formed in an arch shape having a radius of curvature R that connects the apex of the central chevron 8 and the uppermost end in the main groove direction of the formation range in the block 4. The chevron portions 8 located on both sides are formed so that the apex 9 at the center is located on the second protrusion 6.

  Thus, the strength of the block 4 is improved by forming the first protrusion 5 on the side surface of the block 4. And since this 1st protrusion 5 is formed in the sawtooth shape which consists of several mountain-shaped part 8, it is devised so that distortion may not concentrate easily on the base side of the block 4. FIG. In particular, the first protrusion 5 is started from the end in the main groove direction of the base of the block 4. For this reason, it is possible to sufficiently reinforce a portion where groove cracks are most likely to occur. That is, distortion is most easily concentrated at this position because the block 4 bends in the direction of the main groove when traveling on the road surface, but the occurrence of groove cracks is suppressed by starting the first protrusion 5 from this position. be able to. Further, by forming the arch-shaped second ridge portion 6 that connects the apexes of the respective mountain-shaped portions 8 of the first ridge portion 5, the applied stress can be well dispersed. Therefore, the second protrusion 6 can also prevent strain concentration and appropriately prevent the occurrence of groove cracks. In addition, the protrusions are not formed on the groove bottom of the main groove 2 but are not formed on the entire groove wall. Therefore, since the groove volume is not reduced as much as a whole, the drainage performance can be sufficiently exhibited.

  Performance evaluation experiments were conducted on the test tires of Comparative Examples 1 and 2 and Examples 1 to 5.

  Here, tires with a tire size of 195 / 65R15 were used, and after thermal deterioration (left at 70 ° C. ambient temperature for 2 weeks), the time until groove cracking was indexed using a drum tester. did. The running conditions were a test drum diameter: 505 mm, an evaluation rim: 15 × 6.0 J, a slip angle: 1 °, an air pressure: 180 kPa, a load: 540 kgf, and a speed of 40 km / h.

In Comparative Example 1, a grid-like protrusion was formed on the entire surface of the groove wall.
In Comparative Example 2, grid-like protrusions were formed on the entire surface of the groove bottom and on the lower half of the groove wall.
In Examples 1 to 4, the protrusions were configured as shown in FIG. 2, and h, l, a, and b were values shown in Table 1, respectively.
In Example 5, an auxiliary protrusion 10 described later was added to the configuration of Example 1.

  In Table 1, the larger the index value, the higher the groove crack resistance and drainage performance. As can be seen from the results, Examples 1 and 2 exhibited sufficient groove crack resistance and drainage performance compared to Comparative Examples 1 and 2.

(Other embodiments)
In addition, this invention is not limited to the structure described in the said embodiment, A various change is possible.

  For example, in the above embodiment, the first protrusion 5 is formed on the side surface 4a on the main groove 2 side of the block 4, but it may be formed on the side surface 4b on the lateral groove 3 side or both. Good.

  Moreover, in the said embodiment, although the 1st protrusion 5 was formed in the continuous sawtooth shape, for example, it may be a waveform etc. as shown in FIG. 6, and the form is not limited. Moreover, the 1st protrusion 5 does not necessarily need to be completely continuous. For example, as shown in FIG. 7, a discontinuous portion may be included as long as it is substantially continuous and can sufficiently withstand a load acting when traveling on a road surface.

  Moreover, in the said embodiment, although the 1st protrusion part 5 was only formed in sawtooth shape etc., you may make it provide the protrusion part which cross | intersects each protrusion part further. For example, as shown in FIG. 8, you may make it provide the auxiliary | assistant protrusion part 10 which cross | intersects in the center part of the 1st protrusion part 5 (For example, it can be set as a form like Nielsen-Rose bridge. However, the present invention is not limited to this, as long as the protrusions intersect.) According to this configuration, the groove crack resistance can be further improved as compared with the case where the first protrusions 5 that are merely continuous or substantially continuous are provided (see the index of Example 5 in Table 1).

  Moreover, in the said embodiment, although the arch-shaped 2nd protrusion part 6 was formed, even if this 2nd protrusion part 6 does not exist, it is possible to improve a groove crack-proof performance. Moreover, the 2nd protrusion part 6 does not need to cross | intersect the vertex of each mountain-shaped part 8 of the 1st protrusion part 5, and can also be formed in the position away from the 1st protrusion part 5. FIG. is there. However, it is possible to increase the anti-groove crack performance by dispersing the strain more when intersecting. Further, the arch shape may be an upside down shape that protrudes upward at the center portion.

  Moreover, in the said embodiment, although the protrusion part was made into cross-sectional rectangular shape, it can also be set as not only this but a triangle, a semicircle, a semi-ellipse etc., for example. It is preferable to select a shape that is easy to process and less likely to be damaged by subsequent use.

DESCRIPTION OF SYMBOLS 1 ... Tread surface 2 ... Main groove 3 ... Horizontal groove 4 ... Block 5 ... 1st protrusion part 6 ... 2nd protrusion part 7 ... Corner | angular part 8 ... Mountain-shaped part 9 ... Vertex 10 ... Auxiliary protrusion part

Claims (3)

A pneumatic tire having a block obtained by forming a main groove and a lateral groove on a tread surface,
A serrated ridge that continuously or substantially continuously displaces along the side of the block and reverses the direction of displacement at multiple locations ;
An auxiliary ridge that intersects the ridge,
A pneumatic tire characterized by forming a tire. The pneumatic tire according to claim 1 , wherein the protrusion is formed from a corner on the groove bottom side of the block. The pneumatic tire according to claim 1 or 2 , wherein an arch-shaped second protrusion is formed on a side surface of the block.

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