JP6620003B2 - Pneumatic tire - Google Patents

Description

  The present disclosure relates to a pneumatic tire that reduces noise including air column resonance noise.

  When the tire is grounded, a tubular space is formed by the main groove extending in the tire circumferential direction and the road surface. When the tire rotates, air compressed in the tubular space is released to the outside, and as a result, air columnar resonance is generated. The air column resonance sound is annoying noise having a frequency of about 1 kHz, and it has been conventionally required to reduce the air column resonance sound.

  For example, Patent Document 1 discloses a tire that reduces air column resonance noise by irregularly reflecting air by providing a protrusion in a main groove extending in the tire circumferential direction.

JP 2002-29310 A

  However, as in Patent Document 1, when the protrusions are formed so as to face each other on the side walls of two land portions adjacent to each other across the main groove, the groove area is reduced compared to the case where there is no protrusion. Drainage performance will be impaired. In addition, in the configuration in which the apexes of both protrusions are arranged on the tread surface side as in Patent Document 1, the noise reduction effect is appropriately exhibited at the early stage of wear of the tire. It is considered that the noise reduction effect is not exhibited.

  This indication is made paying attention to such a subject, and the object is to provide the pneumatic tire which makes the noise reduction effect and drainage performance show appropriately from the time of a new article to the end of wear.

  In order to achieve the above object, the present disclosure takes the following measures.

The pneumatic tire of the present disclosure is
The tread portion has a main groove extending in the tire circumferential direction, and a center side land portion and a shoulder side land portion that are adjacent to each other across the main groove, and the center side land portion and the shoulder side land portion are tire circumferences. It is arranged in multiple directions,
The side walls forming the main groove of the center side land portion and the shoulder side land portion have a taper-like protrusion in a groove cross-sectional view, and the protrusion includes the center side land portion and the shoulder side land portion. And alternately provided,
The tip of the projecting portion formed in the center side land portion is provided on the tread side rather than half of the maximum depth of the groove,
The tip of the protruding portion formed on the shoulder side land portion is provided on the groove bottom side with respect to half of the maximum groove depth.

  As described above, since the protrusions are alternately provided in the center side land portion and the shoulder side land portion in plan view, there is no protrusion in the shoulder side land portion facing the center side land portion having the protrusion portion. The center side land portion facing the shoulder side land portion having the protrusion portion has no protrusion portion. Therefore, it becomes possible to improve drainage performance compared with the case where there are protrusions on both of the facing side walls.

  Nevertheless, since the tip of the protrusion on the center side land portion is provided on the tread side from half of the maximum depth of the groove, the air column resonance sound generated from the new article to the middle wear is projected on the center side land section. The part is effectively reduced. In addition, since the tip of the protruding portion of the shoulder side land portion is provided on the groove bottom side with respect to half of the maximum depth of the groove, the air column resonance sound generated from the middle wear stage to the late wear stage is Protrusions are effectively reduced. Therefore, it is possible to maintain the effect of reducing the air column resonance noise from the new article to the end of wear.

  Furthermore, since the protrusion part of the center side land part and the protrusion part 4b of the shoulder side land part are provided at different heights, it becomes possible to ensure without deteriorating drainage.

  Therefore, it is possible to provide a pneumatic tire that appropriately exhibits the noise reduction effect and drainage performance from the new article to the end of wear.

The top view which shows typically the tread pattern of the pneumatic tire of this embodiment. Sectional drawing which shows the A1-A1 site | part and B1-B1 site | part of FIG. The top view which shows the protrusion part formed in a block land part. The top view which shows the modification of the protrusion part formed in a block land part. The top view which shows the modification of a tread pattern typically. The figure which shows typically the tread pattern of the pneumatic tire which concerns on the comparative example 2. FIG. The figure which shows typically the tread pattern of the pneumatic tire which concerns on the comparative example 3. FIG.

  Hereinafter, an embodiment of the present disclosure will be described.

  Although not shown in the drawings, the pneumatic tire of the present embodiment is similar to a normal pneumatic tire, a pair of bead cores, a carcass wound around the bead core to form a toroidal shape, and a tire radial direction of a crown portion of the carcass A belt layer disposed on the outer side, and a tread portion disposed on the outer side in the tire radial direction of the belt layer.

  As shown in FIG. 1, the tread portion includes main grooves 1 a and 1 b extending in the tire circumferential direction PD, a lateral groove 2 extending in the tire width direction, and a plurality of blocks defined by the main grooves (1 a and 1 b) and the lateral grooves 2. It has land portions 3a and 3b. Here, the “lateral groove” may be a new state in which the tread surface is divided into a plurality of block land portions, and includes thin grooves and sipes. As long as the main groove extends in the tire circumferential direction, the main groove may coincide with the tire circumferential direction, may be inclined, or may have a zigzag shape. As long as the lateral groove extends in the tire width direction, it may coincide with the tire width direction or may be inclined.

  As shown in FIG. 1, the tread portion has a main groove 1a extending in the tire circumferential direction PD, and a center side land portion 3a and a shoulder side land portion 3b that are adjacent to each other with the main groove 1a interposed therebetween. A plurality of center side land portions 3a and shoulder side land portions 3b are arranged in the tire circumferential direction PD. As shown in FIGS. 1 and 2, the side wall 30 forming the main groove 1a of the center-side land portion 3a and the shoulder-side land portion 3b has tapered projecting portions 4a and 4b in a groove cross-sectional view. In the present embodiment, the side wall 30 is a flat surface. The protrusions 4a and 4b are alternately provided on the center side land portion 3a and the shoulder side land portion 3b. As shown in FIG. 2, the tip P of the protrusion 4a formed on the center-side land portion 3a is provided closer to the tread tr than the half of the maximum groove depth D. The tip P of the protruding portion 4b formed on the shoulder side land portion 3b is disposed on the groove bottom side with respect to half of the groove maximum depth D. In FIG. 2, the groove cross-sectional shape of the protruding portions 4 a and 4 b is a triangular shape, but may be a trapezoidal shape or an arc shape as long as it is a tapered shape.

  The tip P of the protrusion 4a formed on the center side land 3a is in the range of 30 to 40% of the maximum groove depth D from the tread surface tr, and the tip P of the protrusion 4b formed on the shoulder side land 3b. Is preferably in the range of 70 to 80% of the maximum groove depth D from the tread surface tr. In the present embodiment, the tip P of the protrusion 4a formed on the center side land portion 3a is located at a position 35% of the maximum groove depth D from the tread tr, and the protrusion 4b formed on the shoulder side land portion 3b. The tip P is located at 75% of the maximum groove depth D from the tread tr.

  As shown in FIG. 3A, in the plan view, the centers C1 and C3 of the most protruding portions of the protruding portions 4a and 4b are centered on the circumferential centers C2 and C4 of the land portions 3a and 3b. It exists in the range of 15% of circumferential direction length L1, L2. If the protrusions 4a and 4b are out of the above range and are biased in either the front-rear direction, the block rigidity is biased in the front-rear direction. If the block rigidity is deviated in the front-rear direction, the ground pressure is also deviated in the front-rear direction, and as a result, wobbling occurs when going straight. By disposing the projecting portions 4a and 4b in the central portion in the circumferential direction PD of the land portions 3a and 3b as in the present embodiment, the block rigidity is made uniform in the front-rear direction and the straight steering stability performance is improved. In the example of FIG. 3A, the protrusions 4a and 4b protrude in a step shape in plan view. However, as shown in the modification of FIG. 3B, the protrusions 4a and 4b have a trapezoidal shape or a circular shape in plan view. It is the same even if it protrudes in an arc shape.

As shown in FIG. 2, the maximum cross-sectional area of the groove cross section of the protruding portion 4a formed on the center side land portion 3a, than the maximum cross-sectional area of the groove cross section of the projecting portion 4b which is formed on the shoulder side land portion 3b Is also big. When traveling straight, the influence of the block rigidity of the center side land portion 3a on the straight traveling stability is greater than that of the shoulder side land portion 3b. Therefore, by making the maximum cross-sectional area of the protruding portion in the cross-sectional view of the groove larger on the center side than on the shoulder side, it is possible to increase the block rigidity of the center-side land portion 3a and improve the straight running stability performance. If the magnitude relationship is reversed, straight steering stability will deteriorate. Specifically, the maximum cross-sectional area in the groove cross-sectional view of the protruding portion 4a formed in the center-side land portion 3a is 2 to 2 of the maximum cross-sectional area in the groove cross-sectional view of the protruding portion 4b formed in the shoulder-side land portion 3b. It is preferable that it is 4 times in order to exhibit the effect.

  The protrusion amount of the tip P of the protrusion 4a formed on the center side land portion 3a is preferably 25 to 35% of the main groove width W in order to achieve both reduction of air columnar resonance noise and drainage. In the present embodiment, the protrusion amount is 30% of the main groove width W. The protrusion amount of the tip P of the protrusion 4b formed on the shoulder side land portion 3b is preferably 20 to 30% of the main groove width W in order to achieve both reduction of air columnar resonance noise and drainage. In the present embodiment, the protrusion amount is 25% of the main groove width W.

  As shown in FIG. 3A, when the projecting portions 4a and 4b project from the wall surface 30 in plan view, the length of the projecting portions 4a and 4b in the circumferential direction PD is the circumferential direction of the land portions 3a and 3b. It is preferable that it is 50 to 70% of the lengths L1 and L2. This is to achieve both a reduction effect of air columnar resonance noise and drainage performance. If it is less than 50%, the effect of reducing the air column resonance noise is hardly exhibited, and if it exceeds 70%, the drainage performance may be adversely affected. As shown in FIG. 2, it is preferable that the upper end P1 of the protrusion 4a of the center side land portion 3a coincides with the tread surface tr from the viewpoint of securing block rigidity. The lower end P2 of the projecting portion 4a of the center-side land portion 3a is preferably in the range of 60 to 70% of the maximum groove depth D from the tread tr, in order to achieve both noise reduction and drainage performance. It is preferable from the viewpoint of drainage performance that the upper end P3 of the protrusion 4b of the shoulder side land portion 3b is at a position deeper than 50% of the maximum groove depth D from the tread surface tr.

  In this embodiment, as shown in FIG. 1, the main groove 1a, the center side land part 3a, and the shoulder side land part 3b are each arrange | positioned on both sides of the tire width direction WD across the tire equator CL. The arrangement phase of the protrusions 4a and 4b is matched in the circumferential direction PD on one side and the other side in the tire width direction.

  In order to reduce air columnar resonance noise compared to the arrangement of FIG. 1, as shown in FIG. 4, the arrangement phase of the protrusions 4a and 4b is set in the circumferential direction PD on one side and the other side in the tire width direction. It is preferable to make them different.

  Hereinafter, examples and the like that specifically illustrate the configuration and effects of the present disclosure will be described.

(1) Noise reduction performance An index in which the tire size “215 / 55R17 94V” is used, the overall level is measured at 80 km / h in accordance with JASO-C606, and the result when the tire of Comparative Example 1 is new is 100. Expressed in It shows that noise is reduced, so that a numerical value is large. Measurements were made on the initial wear (when new) and the last wear.

(2) Straight running stability performance The test tire is assembled to the rim (17 x 7.0), the internal pressure is set to 230 kPa, the test tire is mounted on all wheels of the actual vehicle, and the vehicle runs straight at a load of 470 kg. Evaluation was made by a sensory test. The result of the tire of Comparative Example 1 is expressed as an index of 100. The larger the value, the better the straight running stability performance.

(3) Drainage performance The test tire is assembled to the rim (17 x 7.0), the internal pressure is 230 kPa, the test tire is attached to all the wheels of the actual vehicle, and the vehicle runs on a straight course with a wet road surface with a depth of 4 mm at a load of 470 kg. Then, the speed when the hydroplaning phenomenon occurs was measured. The evaluation is indicated by an index when the new product of Comparative Example 1 is 100, and the larger the value, the higher the speed and the higher the hydroplaning resistance, that is, the better the drainage performance. Measurements were made on the initial wear (when new) and the last wear.

Example 1
As shown in FIG.1 and FIG.2, the protrusion parts 4a and 4b were provided alternately in the center side land part 3a and the shoulder side land part 3b. The protrusion 4a of the center side land portion 3a is disposed on the tread surface tr side. The protrusion 4b of the shoulder side land portion 3b is disposed on the groove bottom side. The cross-sectional area of the protrusion 4a of the center side land portion 3a is larger than the cross-sectional area of the protrusion 4b of the shoulder side land portion 3b. The arrangement phase of the protrusions 4a and 4b is matched in the circumferential direction PD on one side and the other side in the tire width direction.

Example 2
As shown in FIG. 4, the arrangement phases of the protrusions 4a and 4b are different in the circumferential direction PD on one side and the other side in the tire width direction. Otherwise, it was the same as Example 1.

Comparative Example 1
A tread pattern in which no protrusion was provided in the main groove 1a was formed. Otherwise, the tire was the same as in Example 1.

Comparative Example 2
As shown in FIG. 5, a protrusion 104a is provided on the center-side land 3a, a protrusion 104b is provided on the shoulder-side land 3b adjacent to the center-side land 3a, and the protrusions 104a and 104b face each other. . The protruding portion 104a of the center side land portion 3a is disposed on the tread surface tr side. The protrusion 104b of the shoulder side land portion 3b is disposed on the groove bottom side. The cross-sectional area of the protruding portion 104a of the center-side land portion 3a is larger than the cross-sectional area of the protruding portion 4b of the shoulder-side land portion 3b. Otherwise, it was the same as Example 1.

Comparative Example 3
As shown in FIG. 6, the protruding portion 204b of the shoulder side land portion 3b is arranged at the same size and the same position (treading side) as the protruding portion 204a of the center side land portion 3a. Otherwise, it was the same as Example 1.

  From Table 1, regarding noise reduction performance, Comparative Examples 2, 3 and Examples 1 and 2 all reduce noise when compared to Comparative Example 1 when it is new. In Comparative Example 2 and Examples 1 and 2, noise was reduced compared to Comparative Example 1 at the end of wear. However, it can be seen that Comparative Example 3 has no noise reduction effect at the end of wear. From this, it can be seen that it is effective to vary the position of the protrusions in the vertical direction in order to achieve noise reduction from the initial wear (when new) to the last wear.

  From Table 1, it can be seen that it is effective that the projecting portion of the center side land portion is larger than the projecting portion of the shoulder side land portion 3b with respect to the straight running control stability. The comparative example 2 is more effective than the first and second embodiments because the number of protrusions provided on the center side land portion is simply large.

  From Table 1, since Example 1, 2 is the same as Comparative Example 1 about drainage performance, Example 1, 2 has maintained the drainage performance. On the other hand, in Comparative Examples 2 and 3, the performance at the time of a new article is significantly reduced as compared with Comparative Example 1. It is understood that the projecting portions are arranged in a face-to-face arrangement, and that even if they are arranged alternately, arranging them at the same height has an adverse effect.

  As described above, in the pneumatic tire of the present embodiment, the tread portion includes the main groove 1a extending in the tire circumferential direction, and the center side land portion 3a and the shoulder side land portion 3b adjacent to each other with the main groove 1a interposed therebetween. Have. A plurality of center side land portions 3a and shoulder side land portions 3b are arranged in the tire circumferential direction PD. The side wall 30 that forms the main groove 1a of the center side land portion 3a and the shoulder side land portion 3b has tapered protrusions 4a and 4b in a groove cross-sectional view. The protrusions 4a and 4b are alternately provided on the center side land portion 3a and the shoulder side land portion 3b. The tip P of the protruding portion 4a formed on the center side land portion 3a is provided closer to the tread surface tr than the half of the maximum groove depth D. The tip P of the protruding portion 4b formed on the shoulder side land portion 3b is provided on the groove bottom side with respect to half of the groove maximum depth D.

  Thus, since the protrusion parts 4a and 4b are alternately provided in the center side land part 3a and the shoulder side land part 3b by planar view, the shoulder side land which faces the center side land part 3a which has the protrusion part 4a is provided. The part 3b does not have a protruding part, and the center side land part 3a facing the shoulder side land part 3b having the protruding part 4b has no protruding part. Therefore, it becomes possible to improve drainage performance compared with the case where there are protrusions on both side walls 30 facing each other.

  Nevertheless, since the tip P of the projecting portion 4a of the center side land portion 3a is provided on the tread tr side with respect to half of the maximum groove depth D, air columnar resonance generated from the new article to the middle stage of wear is centered. The protruding portion 4a of the side land portion 3a is effectively reduced. Further, since the tip P of the protruding portion 4b of the shoulder-side land portion 3b is provided on the groove bottom side with respect to half of the maximum groove depth D, the air columnar resonance generated from the middle stage of wear to the late stage of wear is shouldered. The protrusion 4b of the side land portion 3b is effectively reduced. Therefore, it is possible to maintain the effect of reducing the air column resonance noise from the new article to the end of wear.

  Furthermore, since the protrusion part 4a of the center side land part 3a and the protrusion part 4b of the shoulder side land part 3b are provided at different heights, it is possible to ensure without deteriorating drainage.

  Therefore, it is possible to provide a pneumatic tire that appropriately exhibits the noise reduction effect and drainage performance from the new article to the end of wear.

  In the present embodiment, the tip P of the protruding portion 4a formed on the center side land portion 3a is in a range of 30 to 40% of the maximum groove depth D from the tread surface tr, and the protrusion formed on the shoulder side land portion 3b. The tip P of the portion 4b is in the range of 70 to 80% of the maximum groove depth D from the tread surface tr. According to this configuration, since both the protrusions 4a and 4b appropriately protrude into the groove from the initial stage of wear to the end stage of wear, noise reduction can be effectively exhibited and drainage performance can be appropriately ensured. Become.

  In the present embodiment, in the plan view, the centers C1 and C3 of the projecting portions 4a and 4b that are the most projecting are centered on the circumferential centers C2 and C4 of the land portions 3a and 3b, and the circumferential directions of the land portions 3a and 3b. It is in the range of 15% of the lengths L1 and L2. According to this configuration, the block rigidity is made uniform in the front-rear direction, and straight running stability performance is improved.

When traveling straight, the influence of the block rigidity of the center side land portion 3a on the straight traveling stability is greater than that of the shoulder side land portion 3b. In this embodiment, the uppermost large cross sectional area of the groove cross section of the protruding portion 4a formed on the center side land portion 3a, from the outermost large cross sectional area in the groove cross section of the projecting portion 4b which is formed on the shoulder side land portion 3b Is also big. Therefore, by making the maximum cross-sectional area of the protruding portion in the cross-sectional view of the groove larger on the center side than on the shoulder side, it is possible to increase the block rigidity of the center-side land portion 3a and improve the straight running stability performance.

In this embodiment, the uppermost large cross sectional area of the groove cross section of the protruding portion 4a formed on the center side land portion 3a is the top-large cross sectional area in the groove cross section of the projecting portion 4b which is formed on the shoulder side land portion 3b 2 to 4 times. According to this configuration, it is possible to effectively exhibit the straight running stability performance.

  In the present embodiment, the main groove 1a, the center side land portion 3a, and the shoulder side land portion 3b are respectively disposed on both sides of the tire width direction WD across the tire equator CL, and one side and the other side of the tire width direction are arranged. The arrangement phase of the protrusions is different.

  According to this configuration, since the frequency of noise generated on one side in the tire width direction is different from the frequency of noise generated on the other side in the tire width direction, it is possible to reduce noise by avoiding amplification due to frequency matching. .

  As mentioned above, although embodiment of this indication was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present disclosure is indicated not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  The structure employed in each of the above embodiments can be employed in any other embodiment. The specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present disclosure.

DESCRIPTION OF SYMBOLS 1a ... Main groove 3a ... Center side land part 3b ... Shoulder side land part 30 ... Side wall 4a, 4b ... Projection part P ... Tip of projection part PD ... Tire circumferential direction

Claims (6)

The tread portion has a main groove extending in the tire circumferential direction , and a center side land portion and a shoulder side land portion that are adjacent to each other across the main groove, and the center side land portion and the shoulder side land portion are tire circumferences. It is arranged in multiple directions,
The side walls forming the main groove of the center side land portion and the shoulder side land portion have a taper-like protrusion in a groove cross-sectional view, and the protrusion includes the center side land portion and the shoulder side land portion. And alternately provided,
The tip of the projecting portion formed in the center side land portion is provided on the tread side rather than half of the maximum depth of the groove,
The tip of the protruding portion formed on the shoulder side land portion is provided on the groove bottom side than half of the groove maximum depth ,
A pneumatic tire , wherein a tip of the projecting portion is located farther from the groove bottom of the main groove and closer to the tread surface than the groove bottom . The tip of the protruding portion formed on the center side land portion is in a range of 30 to 40% of the maximum groove depth D from the tread surface,
2. The pneumatic tire according to claim 1, wherein a tip of the protruding portion formed on the shoulder side land portion is in a range of 70 to 80% of a maximum groove depth D from the tread surface.   The center of the most projecting part of the projecting part is in a range of 15% of the circumferential length of the land part around the center in the circumferential direction of the land part in plan view. Pneumatic tire. Most large cross sectional area of the groove cross section of the protruding portion formed on the center side land portion is larger than the uppermost large cross sectional area of the groove cross section of the protruding portion formed on the shoulder side land portion, The pneumatic tire according to any one of claims 1 to 3. Most large cross sectional area of the groove cross section of the protruding portion formed on the center side land portion is 2 to 4 of the most large cross sectional area of the groove cross section of the protruding portion formed on the shoulder side land portion The pneumatic tire according to claim 4, which is doubled. The main groove, the center side land portion and the shoulder side land portion are respectively disposed on both sides of the tire width direction across the tire equator,
The pneumatic tire according to any one of claims 1 to 5, wherein an arrangement phase of the protruding portion is different between one side and the other side in the tire width direction.

Images