JP6087616B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  Patent Document 1 describes a pneumatic tire provided with a protrusion forming area in which lattice-like protrusions are formed on the groove surface of a block constituting a main groove. Patent Document 2 describes a pneumatic tire provided with a recessed portion that is recessed so as to form an arch shape on the groove bottom side of the block in order to suppress early uneven wear of the block edge.

  However, in the tires described in Patent Documents 1 and 2, no consideration is given to the suppression of bending in the compression direction (the tire radial direction) of each block. And if each block bends unevenly, since load will be applied unevenly, loss energy will become large and rolling resistance will increase.

JP-A-10-76810 JP 2004-98943 A

It is an object of the present invention to provide a pneumatic tire that can bend the block uniformly to achieve both reduction in rolling resistance and ensuring drainage performance.

In order to solve the above problems, the pneumatic tire of the present invention is a pneumatic tire having a block obtained by forming a main groove and a lateral groove on a tread surface, and is formed on a side surface of the block from a groove bottom. Arch-shaped ridges projecting toward the tread surface are formed, and both ends of the ridges are located in a curved portion formed between the side surface of the block and the groove bottom. It has a configuration. In addition, the protrusion dimension from the said side surface to the front-end | tip in the said protrusion part and the width dimension from the one surface of the tire radial direction in the said protrusion part to another surface are the same.

  Since this tire is provided with an arch-shaped protrusion protruding from the groove bottom side in the block, the applied load (stress) can be dispersed. Moreover, the drag of the compression direction on the side surface of the block can be increased. Therefore, the block can be prevented from being bent and the block can be bent uniformly. Therefore, since a load can be uniformly applied to the entire block (ground dispersibility), loss energy can be reduced and rolling resistance can be reduced. Moreover, the protrusions are not only formed on the groove bottom, but are 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. Furthermore, since uneven distortion of the block can be prevented, occurrence of groove cracks in the main groove can also be suppressed.

  It is preferable to provide a 2nd protrusion part between the said protrusion part and the said tread surface. If it does in this way, the drag of the compression direction in the side of a block can be raised further.

Specifically, the second ridge is displaced continuously or substantially continuously from the ridge, and is formed by inverting the displacement direction at a plurality of locations. The second protrusion is formed in a sawtooth shape that is continuous with the protrusion. If it does in this way, the load added to the compression direction can be disperse | distributed and a block can be bent uniformly.

  It is preferable to form an auxiliary protrusion that intersects the second protrusion. If it does in this way, the drag of the compression direction in the side of a block can be raised further.

  In the pneumatic tire of the present invention, the block is provided with the arch-shaped ridges protruding from the groove bottom side, so that the drag in the compression direction on the side surface of the block can be increased and the block can be bent uniformly. Therefore, since a load can be applied uniformly to the entire block, loss energy can be reduced and rolling resistance can be reduced. In addition, the drainage performance can be sufficiently exerted, and groove cracks generated in the main groove can be suppressed.

The partial top view of the tread surface of the pneumatic tire of the embodiment concerning the present invention. The perspective view which shows a part of tread surface of 1st Embodiment. The fragmentary sectional view of FIG. The side view of 1 block of FIG. The side view of the block of 2nd Embodiment. The side view of the block of 3rd Embodiment. The side view of the block of 4th Embodiment. The side view of the block of 5th Embodiment. The side view of the block of 6th Embodiment. The side view of the block of 7th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a partial plan view of a tread surface 10 of a tire according to the present embodiment, and FIG. 2 shows a part of the tread surface 10. On the tread surface 10, main grooves 11 extending in the circumferential direction are formed in a plurality of rows in the width direction. A plurality of lateral grooves 12 that intersect with the main groove 11 are formed on the tread surface 10. Here, the lateral grooves 12 are inclined in the same direction with respect to the main grooves 11 (here, orthogonal), and are provided at intervals in the circumferential direction. A plurality of blocks 13 are formed on the tread surface 10 by the main grooves 11 and the lateral grooves 12.

  As shown in FIGS. 2 and 3, each block 13 is formed with a first protrusion 14 and a second protrusion 16. The first and second protrusions 14 and 16 of the present embodiment are formed on a side surface 13 a extending along the main groove 11 between the blocks 13 and 13.

  As shown in FIGS. 2 and 4, the first protrusion 14 is formed in an arch shape having a predetermined radius of curvature R that protrudes toward the tread surface 10 from a corner on the groove bottom side of the main groove 11 of the block 13. Has been. In the center of the block 13 along the direction in which the main groove 11 extends, the top 15 of the first protrusion 14 is located. A pair of lower ends of the first protrusions 14 located on the groove bottom side of the main groove 11 is in contact with a curved portion formed between the block 13 and the main groove 11.

The second ridge 16 is provided between the first ridge 14 and the tread surface 10. In the present embodiment, the first protrusion 14 is formed in a sawtooth shape that is continuously displaced from the top 15 and has the displacement direction reversed at a plurality of locations. Specifically, it includes a protruding strip 17a extending from the top 15 of the first protruding portion 14 inclining outward toward the upper side where the tread surface 10 is located. In addition, a ridge piece 17 b that is folded back from the upper end of the ridge piece 17 a and extends downward and inclines downward and intersects the first ridge portion 14 is provided. Furthermore, the strip piece 17 c is provided with a strip piece 17 c that is folded back from the lower end of the strip piece 17 b and is inclined outward and extends toward the corner of the tread surface 10 of the block 13. By these protrusions 17a to 17c, a sawtooth-shaped second protrusion 16 that is continuous with the first protrusion 14 that is continuous in the extending direction of the main groove 11 is formed. The illustrated second protrusion 16 extends at the upper end over the tread surface 10 and contacts a curved portion chamfered with a predetermined curvature. However, the upper end of the second protrusion 16 is not limited to the configuration extending to the tread surface 10, and may be configured to extend to the middle portion of the overall height of the side surface 13a. Will be changed accordingly.

  As shown in FIG. 3, the projecting dimension a from the side surface 13 a of the first and second protrusions 14 and 16 is determined based on the width dimension T of the main groove 11 so as to satisfy the following expression (1). The

Formula 1

      T / 20 ≦ a ≦ T / 5 (1)

  The width dimension b of the first and second protrusions 14 and 16 is determined so as to satisfy the following expression (2) based on the depth dimension H of the main groove 11 (the height dimension of the block 13).

Formula 2

      H / 40 ≦ b ≦ H / 5 (2)

  As shown in FIG. 4, the formation height (the distance from the groove bottom of the main groove 11 to the upper end of the second protrusion 16) h is the depth of the main groove 11. Based on the dimension H, it is determined so as to satisfy the following expression (3).

Formula 3

      H / 4 ≦ h ≦ H (3)

  The formation height (distance from the groove bottom to the top portion 15) l of the first protrusion 14 is determined based on the formation height h of the protrusions 14 and 16 so as to satisfy the following expression (4). .

Formula 4

      h ≦ l ≦ h / 2 (4)

  Since the tire block 13 is provided with the first protrusion 14 that is curved and extended from the groove bottom side, the drag in the compression direction at the side surface 13a can be increased. Moreover, in the present embodiment, since the second protrusion 16 is provided between the first protrusion 14 and the tread surface 10, the drag in the compression direction on the side surface 13 a of the block 13 can be further increased. Therefore, the bending of the block 13 can be suppressed. Moreover, since the 1st protrusion part 14 is formed in arch shape, and the 2nd protrusion part 16 is formed in the serrated shape from the corner | angular part by the side of the tread surface 10, the applied load (stress) can be disperse | distributed. Therefore, it is possible to distribute the load applied in the compression direction and to bend the block 13 uniformly.

  Thus, since the load can be uniformly applied to the entire block 13, loss energy can be reduced and rolling resistance can be reduced. Moreover, the protrusions 14 and 16 are not formed on the groove bottom of the main groove 11 but are 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. Furthermore, since uneven distortion of the block 13 can be prevented, occurrence of groove cracks in the main groove 11 can also be suppressed.

(Second Embodiment)
FIG. 5 shows a block 13 of a tire according to the second embodiment. The second embodiment is different from the first embodiment in that an auxiliary protrusion 18 that intersects the second protrusion 16 is formed. Specifically, the auxiliary ridges 18 are provided so as to intersect at the central portions of the inclined ridges 17a to 17c constituting the second ridges 16 and have a form such as a Nielsen-Rose bridge, for example. . In the second embodiment configured as described above, the same operations and effects as the first embodiment can be obtained. In addition, since the drag in the compression direction on the side surface 13a of the block 13 can be further increased, the block 13 can be bent evenly, and the rolling resistance can be further reduced.

(Third embodiment)
FIG. 6 shows a block 13 of a tire according to the third embodiment. The third embodiment is different from the first and second embodiments in that the second ridge portion 16 is constituted by a plurality of ridge pieces extending in the height direction of the block 13 (the tire radial direction). In the third embodiment configured as described above, the performance is inferior in the dispersion action of the load applied in the compression direction as compared with the first and second embodiments, but the drag in the compression direction is increased by setting the number and position thereof. It can certainly be increased. Thus, the structure of the 2nd protrusion part 16 is not restricted to the sawtooth shape shown to 1st and 2nd embodiment, It can change as needed.

(Fourth embodiment)
FIG. 7 shows a block 13 of a tire according to the fourth embodiment. The fourth embodiment is different from the respective embodiments in that the second protrusion 16 is not provided. The first protrusion 14 has an arc shape that passes through the corner of the block 13 on the groove bottom side, and the formation height l is formed so as to satisfy Expression (4) shown in the first embodiment.

(Fifth embodiment)
FIG. 8 shows a tire block 13 according to the fifth embodiment. The fifth embodiment is different from the fourth embodiment in that the first protrusion 14 is formed in a mountain shape (triangular shape). This 1st protrusion part 14 consists of a pair of linear protrusion piece which passes the corner | angular part of the groove bottom side of the block 13, and the formation height l satisfies Formula (4) shown in 1st Embodiment. Formed.

(Sixth embodiment)
FIG. 9 shows a block 13 of a tire according to the sixth embodiment. The sixth embodiment is different from the fourth embodiment in that the first protrusion 14 is formed in a trapezoidal shape. The first protrusion 14 includes a pair of first protrusions that pass through corners on the groove bottom side of the block 13 and a second protrusion that extends in parallel to the tread surface 10 toward the upper end thereof. The formation height l is formed so as to satisfy the formula (4) shown in the first embodiment.

(Seventh embodiment)
FIG. 10 shows a block 13 of a tire according to the seventh embodiment. The seventh embodiment is different from the fourth embodiment in that the first protrusion 14 is formed in a hexagonal shape such that a square corner is chamfered. The first protrusions 14 are a pair of first protrusions that extend in the compression direction of the block 13 without passing through the corners on the groove bottom side of the block 13, and are inclined inwardly upward from their upper ends. And a third protrusion piece extending parallel to the tread surface 10 toward the upper end thereof, and the formation height l is formed so as to satisfy the expression (4) shown in the first embodiment. Is done.

  As described above, in the fourth to seventh embodiments in which only the first protrusion 14 is formed without forming the second protrusion 16, the compression direction is added as compared with the first to third embodiments. Although the performance is inferior in the dispersion action of the load, the drag in the compression direction can be sufficiently increased and the rolling resistance can be reduced. Moreover, the 1st protrusion part 14 of 1st and 2nd embodiment is not restricted to circular arc shape, It is good also as polygonal arch shape as shown in 5th-7th Embodiment, The structure is as needed. It can be changed.

  For the test tires of Comparative Examples 1 and 2 and Examples 1 to 5, experiments for confirming rolling resistance and drainage performance were performed.

  The test tire was a tire of size 195 / 65R15 91H, mounted on a tire rim of 15 × 6.0 J, and the air pressure was 210 kPa. The comparative example 1 has a configuration in which grid-like protrusions are formed on the entire side surface 13a facing the main groove 11. The comparative example 2 is the structure which formed the grid | lattice-like protrusion part in the whole groove bottom of the main groove 11, and the lower half of the side surface 13a. In Examples 1 to 4, the protrusions 14 and 16 are configured as in the first embodiment shown in FIG. 4, the formation height h of the protrusions 14 and 16, the formation height l of the first protrusion 14, The protrusion dimension a of the protrusions 14 and 16 and the width dimension b of the protrusions 14 and 16 were set to values shown in Table 1 below. Example 5 is the structure of 2nd Embodiment shown in FIG. 5 which added the auxiliary | assistant protrusion part 18 to Example 1. FIG.

  In the rolling resistance experiment, the drum was pressed onto the drum under a load of 495 kgf and rotated to a speed of 80 km / h (2009, TRA standard). Thereafter, the drum driving switch was turned off, the drum was freely rotated, and the rolling resistance was determined and evaluated according to the degree of deceleration. The evaluation is expressed as an index with the value of the rolling resistance of the tire of Comparative Example 1 being 100, and the smaller the value, the better the result.

  In the drainage performance experiment, a 1500 cc class sedan was used as an evaluation vehicle, and the test tire was mounted. Under the condition of a load of 495 kgf, the evaluation vehicle is allowed to go straight into a pool road surface (asphalt) with a water depth of 8 mm at a constant speed. The penetration rate was gradually increased, and the rate at which the hydroplaning phenomenon occurred was evaluated. The evaluation is expressed as an index with the tire speed of Comparative Example 1 as 100, and the higher the value, the less likely hydroplaning occurs and the better the drainage performance.

  As can be seen from the results in Table 1, all the tires of Examples 1 to 5 were able to reduce rolling resistance as compared with Comparative Examples 1 and 2, and exhibited sufficient drainage performance.

  In addition, the pneumatic tire of this invention is not limited to the structure of the said embodiment, A various change is possible.

  For example, in the above-described embodiment, the protrusions 14 and 16 are formed on the side surface 13 a extending along the main groove 11 between the blocks 13 and 13, but are formed on the side surface 13 b extending along the lateral groove 12 between the blocks 13 and 13. Alternatively, it may be provided on both side surfaces 13a and 13b. Moreover, in 1st and 2nd embodiment, although each protrusion piece 17a-17c of the 2nd protrusion part 16 was provided so that it might continue, it should be the structure by which sufficient drag | drug with respect to the load of a compression direction is obtained. For example, it is not always necessary to be completely continuous, and a substantially continuous configuration may be used. Of course, the second protrusion 16 may be discontinuous without intersecting the first protrusion 14.

Moreover, in each said embodiment, although the rib parts 14 and 16 were made into the cross-sectional rectangle shape, it can also be set as not only this but a triangle, a semicircle, a semi-ellipse etc., for example. Processing ease, it is preferable to select the damaged difficulty have shape by subsequent use. Further, in the first to third embodiments, the protrusion dimension a of the protrusions 14 and 16 is formed the same, but the protrusion dimension a1 of the first protrusion 14 is set to be the protrusion dimension of the second protrusion 16. It is preferable to make it larger than a2. This is more effective for suppressing groove cracks.

DESCRIPTION OF SYMBOLS 10 ... Tread surface 11 ... Main groove 12 ... Lateral groove 13 ... Block 13a ... Side surface on the main groove side 13b ... Side surface on the side of the lateral groove 14 ... 1st protrusion 15 ... Top 16 ... 2nd protrusion 17a-17c ... Projection Piece 18 ... Auxiliary ridge

Claims (6)

A pneumatic tire having a block obtained by forming a main groove and a lateral groove on a tread surface,
On the side surface of the block, an arch-shaped ridge protruding from the groove bottom toward the tread surface is formed,
The pneumatic tire according to claim 1, wherein both ends of the protruding portion are located in a curved portion formed between the side surface of the block and the groove bottom . 2. The air according to claim 1 , wherein a protrusion dimension from the side surface to the tip of the protrusion is the same as a width dimension from one surface of the protrusion in the tire radial direction to the other surface. Enter tire.   The pneumatic tire according to claim 1 or 2, wherein a second ridge is provided between the ridge and the tread surface. The said 2nd protrusion part is displaced from the said protrusion part continuously or substantially continuously, and is formed by reversing the displacement direction in several places, It is characterized by the above-mentioned. Pneumatic tires.   The pneumatic tire according to claim 4, wherein the second ridge portion is formed in a sawtooth shape continuous with the ridge portion.   The pneumatic tire according to claim 4, wherein an auxiliary ridge portion that intersects the second ridge portion is formed.

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