JP6580466B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  Conventionally, pattern noise caused by a tread pattern is known as one of noises caused by a tire. In particular, in the block pattern formed by the circumferential groove formed in the tread portion and the transverse groove intersecting the circumferential groove, the tire circumferential direction of the block when the block contacts the road surface as the tire rolls The hitting sound is generated when one end of the hits the road surface. In addition, when the block leaves the road surface, the other end of the block in the tire circumferential direction kicks off the road surface, and a kicking sound is generated, and the deformation of the block that was deformed at the time of contact is restored. A restoration sound is produced. Such impact sounds such as hitting sound, kicking sound and deformation restoring sound are generated as pattern noise at a frequency based on the block formation pitch and the vehicle speed.

  As a method for reducing the pattern noise, for example, Patent Document 1 discloses an area of the block contact surface in the tire circumferential direction that is stepped on for the first contact with the rolling of the tire (hereinafter referred to as a stepping side area). A plurality of holes in a portion other than the belt-like portion connecting the region to be kicked out at the time of separation (hereinafter referred to as a kick-out region), and applying a ground pressure to the belt-like portion. While the impact sound is generated intensively at the part, the impact sound is reduced by reducing the contact pressure outside the area (the part where the hole is formed). As a result, the pattern noise is reduced as a whole block. Is disclosed.

  Further, Patent Documents 2 to 4 disclose that a hole is formed in the block ground surface, and both are aimed at improving the wear resistance of the block.

JP 2007-090980 A JP 2006-168498 A Japanese Patent Laid-Open No. 04-085108 JP 2002-248906 A

  However, in the case of Patent Document 1, since the impact sound increases in the band-like portion where the ground pressure is concentrated at the time of stepping on and kicking out, it may be insufficient as a reduction in pattern noise. In addition, in each of Patent Documents 2 to 4, holes are formed over a wide area of the grounding surface of the block, and the rigidity of the block may be excessively reduced. As a result, the block buckles when grounded. The slip amount between the contact surface and the contact surface increases, and the wear amount particularly in the kick-out side region increases, so that the uneven wear property (toe heel wear) of the block may deteriorate.

  That is, although all of Patent Documents 1 to 4 disclose that pattern elements such as holes are formed on the block ground surface, it is impossible to achieve both reduction of pattern noise and improvement of uneven wear.

  This invention is made | formed in view of the said subject, and it aims at obtaining the pneumatic tire which can improve uneven wear property, reducing pattern noise.

The present invention is a pneumatic tire provided with a plurality of block portions partitioned by a plurality of circumferential grooves extending in the circumferential direction of the tread portion and a plurality of lateral grooves intersecting with the circumferential grooves, It is located on the stepping side at the time of contact, and is located on the stepping side region where one or more pattern elements recessed toward the radially inner diameter side are formed, and on the kicking side at the time of contact, One or a plurality of the pattern elements are formed, and are positioned between the kick-out side area, the stepping-side area, and the kick-out side area, and the pattern elements are not formed and are formed flat. Further, it is divided into a central region and three regions in the tire circumferential direction, and the pattern elements are separated from the lateral grooves .

  Here, the pattern elements include those that form a gap and a notch extending in the tire radial inner diameter side in the block portion, and are formed as holes, dimples, and sipes, for example.

  According to the present invention, the rigidity of the stepping side area and the kicking side area can be appropriately reduced by the pattern element, and can be appropriately bent at the time of grounding and separation. Therefore, the striking sound when the block is stepped on (when touching the ground) is reduced, and when kicking out (when leaving), the kicking sound is reduced, and the deformation of the block is reduced and the deformation is restored. To reduce. Therefore, pattern noise is reduced.

  On the other hand, since the pattern element is not formed in the central area, the rigidity of the central area does not decrease, so the rigidity of the entire block is excessively reduced while reducing the rigidity of the stepping side area and the kicking side area. It is possible to suppress the lowering, which prevents the block from buckling at the time of grounding. Furthermore, by reducing the rigidity of the kick-out area, the shear force in the kick-out area can be easily borne by the entire block. As a result, at the time of separation, the slip amount in the kick-out area is reduced, so that wear in the kick-out area is suppressed and toe heel wear is reduced. Therefore, uneven wear resistance is improved.

  The pattern element is preferably configured as a hole extending in the tire radial direction.

  According to this configuration, the pattern element can be easily formed.

The central region preferably has a tire circumferential length that is not less than 1/3 and not more than 1/2 of a tire circumferential length of the block portion.

  According to this configuration, since the central region does not become excessively small, the rigidity of the entire block can be ensured, and the block can be prevented from buckling during grounding.

  It is preferable that a plurality of the pattern elements are formed, and the pattern element portion located on the lateral groove side is formed deeper than the pattern element portion located on the central region side.

  According to this configuration, the rigidity on the lateral groove side of the block portion can be effectively reduced, and the rigidity on the central region side can be prevented from excessively decreasing. Accordingly, uneven wear can be improved while reducing noise during stepping on and kicking out.

  It is preferable that the said pattern element is extended in parallel along the transverse groove side wall part defined by the said transverse groove of the said block part seeing from a tire axial direction.

  According to this configuration, even during wear, the positional relationship (distance) between the gap formed by the pattern element and the wall surface of the side wall of the block portion can be maintained. The rigidity of the side region and the kicking side region can be stably reduced.

In particular, when the lateral groove sidewall portion is inclined with respect to the tire radial direction, the rigidity can be stably reduced even during wear by inclining the pattern elements in parallel. For example, when the lateral groove side wall is inclined so as to spread toward the inner diameter side in the tire radial direction and the pattern element is formed so as to extend parallel to the tire radial direction, the gap portion and the lateral groove due to the pattern element as wear progresses. The distance between the side wall portion and the wall surface increases, and the effect of reducing the rigidity by the pattern elements in the stepping side region and the kicking side region changes.
Preferably, the pattern element is formed in a plurality of steps in the tire circumferential direction in the stepping side end region or the kicking side end region, and among the pattern elements formed in the plurality of steps, the pattern element The pattern element located on the lateral groove side has an opening on the surface of the tread portion larger than the pattern element located on the central area side.
Preferably, the block portion has a portion in which a position in a tire circumferential direction of a width direction edge portion located at an end portion on a kicking side or a stepping side is changed, and the pattern element is formed on the stepping side. A plurality of tire regions are formed in the tire width direction in the end region or the kick-out side end region, and the tire is separated from the central region in the width direction edge of the block portion among the plurality of pattern elements. The pattern element formed in the most projecting portion in the circumferential direction has an opening on the surface of the tread portion larger than the remaining pattern elements in the stepping side area or the kicking side area where the pattern element is formed. .

  The pneumatic tire according to the present invention can improve uneven wear resistance while reducing pattern noise.

The top view which expands and shows the tread pattern formed in the tread part of the pneumatic tire concerning one embodiment of the present invention. The top view of the block of FIG. Sectional drawing of the block along the III-III line | wire of FIG. The top view of the block which shows the modification which changed the arrangement number of the hole in the tire circumferential direction. The top view of the block which shows the further modification of FIG. 4A. The top view of the block which shows the modification which changed the arrangement number of the hole in the tire width direction. The top view of the block which shows the further modification of FIG. 5A. The top view of the block which shows the modification which changed the magnitude | size of the hole. The top view of the block which shows the further modification of FIG. 6A. Sectional drawing of the block which shows the modification which changed the depth of the hole. FIG. 7B is a cross-sectional view of a block showing a further modification of FIG. 7A. Sectional drawing of the block which shows the modification which inclined the hole. FIG. 8B is a cross-sectional view of a block showing a further modification of FIG. Sectional drawing of the block which shows the modification in the block in which the lateral groove side wall part inclined. FIG. 9B is a cross-sectional view of a block showing a further modification of FIG. 9A. Sectional drawing of the block which shows the modification which deform | transformed the shape of the hole in the depth direction. FIG. 10B is a cross-sectional view of a block showing a further modification of FIG. 10A. The top view of the block which shows the modification which changed the opening shape of the hole. The top view of the block which shows the further modification of FIG. 11A. The top view of the block which concerns on the comparative example 1. FIG. The top view of the block which concerns on the comparative example 2. FIG. The top view of the block which concerns on the comparative example 3. FIG. FIG. 3 is a plan view of a block according to the first embodiment. FIG. 6 is a plan view of a block according to a second embodiment. FIG. 6 is a plan view of a block according to a third embodiment.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In addition, the following description is only illustrations essentially and does not intend restrict | limiting this invention, its application thing, or its use. Further, the drawings are schematic, and the ratio of each dimension is different from the actual one.

  FIG. 1 is a plan view showing a developed tread portion 2 of a pneumatic tire 1 according to an embodiment of the present invention. As shown in FIG. 1, the tread portion 2 includes a plurality of main grooves (circumferential grooves) 3 extending in the tire circumferential direction and a plurality of horizontal grooves (lateral grooves) that intersect the main grooves 3 and extend in the tire width direction. 4), and a plurality of blocks (block portions) 5 are defined by the main grooves 3 and the lateral grooves 4.

  The main groove 3 extends parallel to the tire circumferential direction. The lateral groove 4 has a central lateral groove 4A extending in the tire width direction at the center of the tread portion 2 in the tire width direction, and continuously on both sides of the central lateral groove 4A in the tire width direction, outward in the tire width direction, with respect to the tire width direction. And a pair of side lateral grooves 4B extending in an inclined manner. A rectangular block 5A is formed in the center of the tread portion 2 in the tire width direction by the main groove 3 and the central portion lateral groove 4A, and the main groove 3 and the side on both sides of the tread portion 2 in the tire width direction. A parallelogram block 5B is formed by the partial lateral groove 4B.

  Next, the configuration of the block 5 will be specifically described using the block 5B as an example. FIG. 2 shows an enlarged view of one of the blocks 5B. As shown in FIG. 2, in the tire circumferential direction, the block 5 includes a stepping-side region 51 positioned on the advance side in the tire rotation direction R, a kick-out region 53 positioned on the delay side in the tire rotation direction R, and a stepping-in. The region is divided into three regions, a central region 52 located between the side region 51 and the kick-out region 53.

  The stepping-side region 51 is a region where the block 5 is not in contact with the road surface and starts to contact the road surface first as the tire 1 rolls, and the kick-out region 53 is in contact with the block 5. This is a region where the tire 1 finally leaves the road surface as the tire 1 rotates.

  A plurality of pattern elements 6 are formed in the stepping-side area 51 and the kick-out area 53, and the pattern element 6 is not formed in the central area 52 and is formed flat. The pattern element 6 is recessed from the contact surface of the block 5 toward the inner diameter side in the tire radial direction, and is formed as a gap or a notch extending from the surface of the block 5 to the inner diameter side in the tire radial direction. ing. In the present embodiment, the pattern element 6 is formed as a hole, but may be formed by, for example, dimples, sipes, or the like.

  The block 5 is formed point-symmetrically in the tire circumferential direction, and the tire circumferential direction length L1 of the stepping side region 51 and the tire circumferential direction length L3 of the kicking side region 53 are respectively the tire circumferential direction of the block 5. The longitudinal length L2 is configured to be ¼ or more and ３ or less of the directional length L0, and the tire circumferential direction length L2 of the central region 52 is １ ／ or more of the tire circumferential direction length L0 of the block 5. It is comprised so that it may become a length of 1/2 or less.

  Here, the tire circumferential direction length L0 of the block 5 refers to the end portion of the block 5 that is located closest to the advance side in the tire rotation direction R and the end that is located closest to the delay side of the tire rotation direction R in the tire circumferential direction. 2, in the case of the parallelogram block 5B as shown in FIG. 2, the length of the tire circumferential component between the acute corners 55 and 56 located at both ends in the tire circumferential direction. Means.

In this embodiment, the opening shape of the pattern element 6 is a circular shape, and the size of the pattern element 6 is such that foreign matter such as pebbles is difficult to bite. 8mm ² more than 50mm ² is set to be equal to or less than. Further, the pattern element 6 is formed in two steps in the circumferential direction in the stepping-side area 51 and the kicking-out area 53, and a plurality of pattern elements 6 are formed with the same size.

  Moreover, the opening ratio by the pattern element 6 in each of the stepping-side area 51 and the kicking-out area 53 is set to 5% or more and 50% or less. Here, the opening ratio is defined as the ratio of the total opening area of all the pattern elements 6 to the surface area of the stepping side area 51 or the kicking side area 53 of the block 5.

  FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 and shows a cross section of the pattern element 6 as viewed from the tire axial direction. As shown in FIG. 3, the pattern elements 6 extend in the same shape in the tire radial direction, and are formed to a depth D of 10% or more and 90% or less of the block height H.

  In addition, the porosity of the pattern element 6 in each of the stepping-side area 51 and the kicking-out area 53 is set to 5% or more and 50% or less. Here, the porosity is defined as the ratio of the total volume of all the pattern elements 6 to the total volume of the stepping-side area 51 or the kicking-side area 53 of the block 5.

  As described above, in the block 5, since the plurality of pattern elements 6 are formed in the stepping side region 51 and the kicking side region 53 in the tire circumferential direction, the rigidity of the stepping side region 51 and the kicking side region 53 is effectively increased. Can be reduced.

  Accordingly, when the block 5 is stepped on (at the time of grounding), the impact due to the stepping is reduced by the bending of the stepping-side region 51, and when the block 5 is kicked out (at the time of separation from the road surface), the kick-out region The flexure of 53 reduces the impact caused by kicking out, and can moderate the deformation and restoration of the block. Therefore, the striking sound in the stepping-side area when touching is reduced, and the kicking sound and deformation restoring sound in the kicking-out area are reduced when leaving.

  On the other hand, since the pattern element 6 is not formed in the central region 52 and is formed flat, the rigidity of the central region 52 does not decrease. Thus, while the pattern elements 6 are formed in the stepping-side area 51 and the kick-out area 53, the rigidity of the entire block 5 is not excessively lowered, and the buckling of the block 5 is suppressed at the time of ground contact.

  Further, the pattern element 6 formed in the kick-out area 53 reduces the rigidity of the kick-out area 53, so that the kick-out area 53 is easily bent at the time of kicking, and the shear force is exerted on the block 5 as a whole. It becomes easy to bear. As a result, when kicking out, the slip amount in the kicking side region 53 is reduced, so that wear of the kicking side region 53 is suppressed, and as a result, the toe heel wear amount is reduced.

  Therefore, by forming the pattern element 6 only in the stepping-side area 51 and the kick-out area 53 and not forming the pattern element 6 in the central area 52, the pattern noise of the tire is effectively reduced, but the partial wear is reduced. (Toe heel wear) can be improved

  Further, since the circumferential length L2 of the central region 52 where the pattern element 6 is not formed is at least one third of the block length L0, the rigidity of the block 5 does not decrease excessively. On the other hand, the circumferential lengths L1 and L3 of the stepping side area 51 and the kicking side area 53 where the pattern element 6 is formed are at least 1/4 of the block length L0. Rigidity can be reduced moderately, and impact sound when stepping on and kicking out can be effectively suppressed.

  Further, the stepping side region 51 and the kicking side region 53 are formed so that the opening ratio by the pattern element 6 is not less than 5% and not more than 50%. Can be reduced moderately. That is, if the aperture ratio is less than 5%, the rigidity of the stepping-side area 51 and the kicking-out area 53 cannot be effectively reduced, and the reduction of the impact sound is insufficient. On the other hand, if the opening ratio is larger than 50%, the rigidity of the stepping-side area 51 and the kicking-out area 53 is excessively decreased, and the slip amount is increased. As a result, the wear amount is increased.

  Similarly, the stepping-side region 51 and the kicking-side region 53 are formed so that the porosity of the pattern element 6 is 5% or more and 50% or less. Rigidity can be reduced moderately. That is, if the porosity is less than 5%, the rigidity of the stepping-side region 51 and the kicking-out region 53 cannot be effectively reduced, and the reduction of the impact sound is insufficient. On the other hand, when the porosity is larger than 50%, the rigidity of the stepping-side region 51 and the kicking-out region 53 is excessively lowered, and the slip amount is increased, and as a result, the wear amount is increased.

  Moreover, it can form easily by forming the pattern element 6 as a hole. However, as described above, the pattern element 6 may be formed as dimples or sipes in addition to the holes.

  In the above embodiment, the pattern elements 6 are formed in two steps in the tire circumferential direction. Alternatively, the pattern elements 6 may be formed in one step in the tire circumferential direction as shown in FIG. 4A. You may form in three steps in a direction. In any case, if the pattern elements 6 are not connected to each other and are not formed in the central region 52, the rigidity of the block 5 is not excessively lowered, and the wear of the block 5 is deteriorated. Can be suppressed.

  Further, as shown in FIG. 5A, the pattern element 6 may be formed only on one end side in the tire width direction of the stepping side region 51 and the kicking side region 53 of the block 5. In particular, in the parallelogram-shaped block 5B, when the step is performed by forming the sharp corners 55 and 56 that first contact with the road surface and finally leave the road surface in the stepping side region 51 and the kicking side region 53. In addition, it is easy to suppress the impact sound when kicking out more effectively.

  Further, as shown in FIG. 5B, the pattern element 6 may be formed only in the center portion in the tire width direction of the stepping side region 51 and the kicking side region 53 of the block 5. This also makes it possible to easily maintain the rigidity of the corners of the block 5 and suppress the chipping of the corners while effectively reducing the rigidity of the stepping-side area 51 and the kicking-out area 53 of the block 5.

  Further, as shown in FIGS. 6A and 6B, the sizes of the plurality of pattern elements 6 may be different in one block. That is, as shown in FIG. 6A, among the pattern elements 6 formed in the stepping-side area 51 and the kick-out area 53, the pattern element 6 positioned on the lateral groove 4 side is the pattern in which the opening is positioned on the center area 52 side. It may be formed larger than the element 6. As a result, the rigidity of the block 5 on the side of the lateral groove 4 can be effectively reduced, and the rigidity on the side of the central region 52 can be prevented from excessively decreasing. Therefore, it is possible to prevent an increase in the amount of toe heel wear by preventing the rigidity of the entire block 5 from being excessively lowered while reducing the noise at the time of stepping on and kicking out.

  Further, as shown in FIG. 6B, among the pattern elements 6 formed in the stepping-side area 51 and the kick-out area 53, the pattern element 6 located on one end side in the tire width direction has a large opening. Also good. In particular, in the parallelogram-shaped block 5B, the impact at the time of stepping and kicking is reduced by forming the pattern element 6 large at the acute corners 55 and 56 that first contact the road surface and finally leave the road surface. Easy to suppress more effectively.

  Further, as shown in FIGS. 7A and 7B, the depth of the plurality of pattern elements 6 may be made different in the block 5. That is, as shown in FIG. 7A, among the pattern elements 6 formed in the stepping-side area 51 and the kick-out area 53, the pattern elements 6 located on the lateral groove 4 side are formed to have a greater depth. Also good. As a result, the rigidity of the block 5 on the side of the lateral groove 4 can be effectively reduced, and the rigidity on the side of the central region 52 can be prevented from excessively decreasing. Therefore, it is possible to prevent an increase in the amount of toe heel wear by preventing the rigidity of the entire block 5 from being excessively lowered while reducing the noise at the time of stepping on and kicking out.

  Further, as shown in FIG. 7B, the depth of the plurality of pattern elements 6 may be varied only in one of the stepping-side region 51 and the kicking-out region 53.

  Further, as shown in FIGS. 8A and 8B, the pattern element 6 may be inclined with respect to the tire radial direction. FIG. 8A shows a case where the pattern element 6 is inclined toward the central region 52 side as it progresses toward the inner diameter side in the tire radial direction, and FIG. 8B shows that the pattern element 6 moves toward the lateral groove 4 side as it proceeds toward the inner diameter side in the tire radial direction. The case where it inclines is shown.

  Further, as shown in FIGS. 9A and 9B, when the lateral groove side wall portion 57 defined by the lateral groove 4 is inclined with respect to the tire radial direction among the wall portions of the block 5, it is viewed from the tire axial direction. The pattern element 6 may be inclined so as to extend substantially in parallel along the lateral groove side wall portion 57. FIG. 9A shows the block 5 formed so as to spread toward the inner diameter side in the tire radial direction, and the pattern element 6 is formed so as to be inclined along the inclination of the lateral groove side wall portion 57.

  As a result, the positional relationship (distance) between the gap formed by the pattern element 6 and the lateral groove side wall portion 57 can be maintained substantially constant even during wear. In addition, the rigidity of the kick-out side region 53 can be stably reduced.

  On the contrary, when the lateral groove side wall portion 57 is inclined so as to expand downward, when the pattern element 6 is formed so as to extend parallel to the tire radial direction, the gap portion and the lateral groove side wall portion due to the pattern element 6 are worn during wear. The distance to 57 increases, and the rigidity reduction margin in the stepping-side area 51 and the kick-out area 53 changes, and in particular, the rigidity reduction margin in the vicinity of the lateral groove 4 decreases.

  Further, as shown in FIG. 9B, the pattern element 6 may be formed so as to be bent by combining a plurality of holes, and although not shown, the pattern element 6 may be formed so as to be bent. Good. By forming the pattern element 6 in this way, the degree of freedom in forming the pattern element 6 is increased, and the rigidity of the stepping side area 51 and the kicking side area 53 of the block 5 is set to the shape of the lateral groove side wall 57, for example. In addition, it is easy to reduce suitably.

  10A and 10B, the shape of the pattern element 6 may be changed in the depth direction. That is, as shown to FIG. 10A, you may form so that a cross-sectional shape may become small as the pattern element 6 progresses to a depth direction. As a result, the foreign matter caught in the pattern element 6 can be easily discharged by the deformation of the block 5 when it is grounded and separated.

  Further, as shown in FIG. 10B, the pattern element 6 may be formed so that the cross-sectional shape becomes larger as it advances in the depth direction. Thereby, while reducing the area opened to the tread surface, it is easy to increase the volume of the gap portion by the pattern element 6, and it is easy to suppress the biting of foreign matter into the pattern element 6 by the reduced opening. Moreover, although illustration is abbreviate | omitted, you may combine various cross-sectional shapes so that the pattern element 6 may have an enlarged diameter part and a reduced diameter part in the depth direction.

  Further, as shown in FIGS. 11A and 11B, the pattern element 6 may be formed in an elliptical shape instead of a circle, or may be formed in a polygonal shape. As shown in FIG. 11A, by forming the pattern element 6 on an ellipse, the degree of freedom in forming the pattern element 6 can be increased. Further, as shown in FIG. 11B, by forming the pattern element 6 in a polygonal shape, for example, the pattern element 6 along the contour shape of the block 5 can be formed, and the rigidity of the block 5 is more efficiently reduced. it can.

  Evaluation tests for noise and uneven wear resistance were performed on the pneumatic tires of Comparative Examples 1 to 3 and Examples 1 to 3 shown in Table 1 below.

  As shown in FIG. 12A, the pneumatic tire of Comparative Example 1 is not formed with pattern elements, and the step-in area 51, the central area 52, and the kick-out area 53 are formed flat.

As shown in FIG. 12B, in the pneumatic tire of Comparative Example 2, holes as the pattern elements 6 are formed in each of the stepping side region 51, the central region 52, and the kicking side region 53. Opening area of each hole is a 10 mm ^2, in each of the regions 51 to 53, a total of six holes in the two stages in the tire circumferential direction are formed in three rows in the tire width direction.

  As shown in FIG. 12C, in the pneumatic tire of Comparative Example 3, three sipes 60 extending in the tire width direction are used instead of the holes as the pattern elements 6 formed in the central region 52 with respect to Comparative Example 2. The only difference is that it is formed, the others are the same.

  As shown in FIG. 13A, the pneumatic tire of Example 1 is different from Comparative Example 2 only in that the pattern element 6 is not formed in the central region 52, and the others are the same.

  As shown in FIG. 13B, in the pneumatic tire of the second embodiment, the number of pattern elements 6 is different from that of the first embodiment. Specifically, in the stepping side region 51 and the kicking side region 53, the tire A total of ten holes are formed in five rows in the width direction and two steps in the tire circumferential direction. That is, the number of pattern elements 6 is larger than that in the first embodiment. That is, the aperture ratio (void ratio) by the pattern element 6 is larger than that of the first embodiment.

As shown in FIG. 13C, the pneumatic tire of Example 3 is formed on the side of the central region 52 among the pattern elements 6 formed in the stepping side region 51 and the kicking side region 53 with respect to Example 1. The only difference is that the opening area of the pattern element 6 is 5 mm ² , and the others are the same. That is, the aperture ratio (void ratio) by the pattern element 6 is smaller than that of the first embodiment.

  In Comparative Examples 2 and 3 and Examples 1 to 3, the aperture ratio and the void ratio in each of the regions 51 to 53 by the pattern element 6 are set to 5% or more and 50% or less.

  In the noise evaluation test, the level of the primary pitch peak when the noise measurement course was run at a speed of 80 km / h was measured. The performance of the remaining Comparative Examples 2 and 3 and Examples 1 to 3 is indexed with the case of Comparative Example 1 being 100, and the lower the index, the better the noise performance. Here, the primary pitch peak is an impact sound that occurs when the end of the block on the stepping side comes into contact with the ground (or the end of the block kicking side comes off), and is the block pitch per tire lap. It occurs at a frequency based on the number of formations (formation pitch) and the number of rotations of the tire.

  In the evaluation test for uneven wear resistance, the difference between the amount of wear in the stepping-side region and the amount of wear in the kick-out region when traveling a specified distance with an actual vehicle was measured as the toe heel amount. The performance of the remaining Comparative Examples 2 and 3 and Examples 1 to 3 is indexed with the case of Comparative Example 1 being 100, and the higher the index, the better the uneven wear resistance performance.

  In Comparative Examples 2 and 3 and Examples 1 to 3 in which the pattern element 6 is formed, the noise performance is lower than 100, which is superior to Comparative Example 1 in which the pattern element 6 is not formed. In particular, in comparison with Examples 1 to 3, the larger the aperture ratio (void ratio) of the pattern elements 6 formed in the stepping side area 51 and the kicking side area 53, the better the noise performance.

  This is because the rigidity in the stepping side region 51 and the kicking side region 53 is suitably reduced by forming more pattern elements 6 so that the rigidity is not excessively reduced in the stepping side region 51 and the kicking side region 53. This is probably because it can be done.

  On the other hand, in Comparative Examples 2 and 3 in which the pattern elements 6 such as holes and sipes are formed in the central region 52, the uneven wear resistance is less than 100, which is worse than that in Comparative Example 1. Further, in Examples 1 to 3 in which the pattern elements 6 such as holes and sipes are not formed in the central region 52, the wear resistance exceeds 100 and is improved as compared with Comparative Example 1.

  In Comparative Examples 2 and 3, since the pattern element 6 is formed in the central region 52, the rigidity of the entire block 5 is excessively lowered, and the amount of slip increases due to the block 5 being buckled at the time of ground contact. As a result, the amount of wear increases on the contrary, and it is considered that uneven wear resistance deteriorates.

  In the first to third embodiments, since the pattern element 6 is not formed in the central region 52, the rigidity of the entire block 5 is not excessively lowered, and the pattern element 6 formed in the kick-out side region 53 is kicked out. Since the rigidity of the side region 53 can be suitably reduced, the shear deformation of the block 5 at the time of kicking can be borne by the entire block 5. As a result, the amount of slip in the kick-out area 53 is reduced, so that the amount of wear in the kick-out area 53 is reduced and the uneven wear resistance is improved.

  In the said embodiment, since the block 5 is formed point-symmetrically in the tire circumferential direction, the pneumatic tire 1 is not a tire with a rotational direction designated. However, the blocks 5 need not be formed point-symmetrically with respect to the tire circumferential direction.

  In the above embodiment, the pattern elements are formed in both the stepping side region 51 and the kicking side region 53 of the block 5, but the pattern element 6 is formed in any one of the stepping side region 51 and the kicking side region 53. May be.

  In the above embodiment, the case where the pattern elements 6 are formed for all the blocks 5 in the tread portion 2 has been described as an example. However, the present invention is not limited to this, and the specific adjacent main grooves 3 in the specific tire width direction are not limited thereto. It may be formed only for the block 5 formed between the three, or may be formed on the block 5 randomly selected from the tread portion 2.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Main groove 4 Lateral groove 5 Block 6 Pattern element 51 Step side area 52 Center area 53 Kick-out side area 57 Side groove side wall part

Claims (7)

A pneumatic tire provided with a plurality of block portions defined by a plurality of circumferential grooves extending in the circumferential direction of the tread portion and a plurality of lateral grooves intersecting the tread portion,
The block part is
A stepping-side region, which is located on the stepping side at the time of ground contact and in which one or a plurality of pattern elements recessed toward the radially inner diameter side is formed;
A kick-out side region, which is located on the kick-out side at the time of contact, and in which one or a plurality of the pattern elements are formed;
It is located between the stepping side region and the kicking side region, and is divided into three regions in the tire circumferential direction and a central region that is formed flat without the pattern element being formed. And
The pneumatic tire is spaced apart from the lateral groove .   The pneumatic tire according to claim 1, wherein the pattern element is configured as a hole extending in a tire radial direction. The pneumatic tire according to claim 1 or claim 2, wherein the central region has a tire circumferential length that is not less than 1/3 and not more than 1/2 of a tire circumferential length of the block portion. A plurality of the pattern elements are formed,
The air according to any one of claims 1 to 3 , wherein the pattern element located on the lateral groove side is formed deeper than the pattern element located on the central region side. Enter tire. The said pattern element is extended in parallel along the lateral groove side wall part defined by the said horizontal groove of the said block part seeing from a tire axial direction, The any one of Claims 1-4. Pneumatic tires.   The pattern element is formed in a plurality of steps in the tire circumferential direction in the stepping side end region or the kicking side end region.
  Of the pattern elements formed in the plurality of stages, the pattern element located on the lateral groove side has an opening on the surface of the tread portion larger than the pattern element located on the center area side,
  The pneumatic tire according to any one of claims 1 to 5.   The block portion has a portion where the position in the tire circumferential direction of the width direction edge portion located at the end portion on the kicking side or the stepping side is changed,
  A plurality of the pattern elements are formed in the tire width direction in the stepping side end region or the kicking side end region,
  Of the plurality of pattern elements, the pattern elements formed on the most protruding portion in the tire circumferential direction so as to be separated from the central region of the edge in the width direction of the block portion are on the surface of the tread portion. The opening is larger than the remaining pattern elements in the stepping side area or the kicking side area where the pattern element is formed,
  The pneumatic tire according to any one of claims 1 to 6.

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