JP2010006095A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of reducing an air column resonance sound, while suppressing uneven wear, without reducing maneuvering stability. <P>SOLUTION: This pneumatic tire is provided by partitioning land parts 10-50 of a plurality of rows by main grooves, by arranging a plurality of main grooves 1a-1d extending in the tire peripheral direction in a tread part T. A plurality of cutout parts 31 having a triangular curved surface 31a in a plan view are arranged in an edge part facing the main grooves 1b and 1c of the land part 30 of at least one row, and the curved surface 31a of these cutout parts 31 are formed so as to contact with a tread of the land part 30 on one side of a triangle without having a ridgeline. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire having a plurality of main grooves extending in the tire circumferential direction in a tread portion, and more particularly, air column resonance while suppressing occurrence of uneven wear without deteriorating steering stability. The present invention relates to a pneumatic tire that can reduce noise.

  A pneumatic tire usually includes a plurality of main grooves extending in the tire circumferential direction in a tread portion. These main grooves have a relatively large cross-sectional area and support drainage performance. However, in a main groove having a relatively large cross-sectional area, air column resonance sound having a frequency of about 800 to 1500 Hz is likely to occur during traveling. Such air column resonance sound is considered to be a cause of tire noise called passing sound or vehicle exterior noise.

In contrast, in the land portion adjacent to the main groove, it is proposed to reduce air column resonance noise by providing a plurality of lug grooves with one end opening in the main groove and the other end terminating in the land portion. (For example, refer to Patent Document 1). However, when the air column resonance noise is reduced based on such a one-end closed type lug groove, the rigidity of the land portion is significantly reduced, and there is a disadvantage that the steering stability is lowered. In addition, there is a disadvantage that uneven wear tends to occur in the land portion partitioned by the lug groove.
JP 2007-168597 A

  An object of the present invention is to provide a pneumatic tire that can reduce air column resonance noise while suppressing the occurrence of uneven wear without reducing steering stability.

  In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire in which a plurality of main grooves extending in the tire circumferential direction are provided in a tread portion and a plurality of rows of land portions are defined by the main grooves. A plurality of cutout portions having a triangular curved surface in plan view are provided at an edge facing the main groove of the land portion of the row, and the curved surface of the cutout portion is provided on the tread surface of the land portion on one side of the triangle. On the other hand, it is formed so as to contact without having a ridgeline.

  In the present invention, a plurality of cutout portions having a triangular curved surface in a plan view are provided at an edge facing the main groove of at least one row of land portions, and the curved surface of these cutout portions is formed on one side of the triangle. By forming it so that it touches the tread surface of the land portion without having a ridgeline, it forms a wide space that communicates with the main groove without significantly reducing the rigidity of the land portion. The air column resonance generated in the main groove can be reduced without lowering. In addition, by forming the curved surface of the notch so as to be in contact with the tread surface of the land portion without having a ridge line at one side of the triangle, the occurrence of uneven wear starting from the notch is suppressed. Can do.

  In the present invention, the width in the tire axial direction of the notch is 20% to 50% of the width of the land, and the depth of the notch is 10% to 125% of the effective groove depth of the main groove. The length in the tire circumferential direction of the portion is preferably 10% to 50% of the pitch length in the tire circumferential direction of the notch. Moreover, it is preferable to provide the protrusion which protrudes in a main groove in the position adjacent to the deepest part of a notch part. Thereby, air column resonance can be reduced more effectively.

  In the present invention, the notch portion can be formed in any land portion adjacent to the main groove. More specifically, in the pneumatic tire in which four main grooves extending in the tire circumferential direction are provided in the tread portion and five rows of land portions are defined by these main grooves, both of the land portions located at the most tread center side are provided. It is preferable to provide a notch at each edge. Further, in a pneumatic tire in which four main grooves extending in the tire circumferential direction are provided in the tread portion and five rows of land portions are partitioned by these main grooves, the main groove is sandwiched between the main groove on the tread center side and the main groove on the shoulder side. It is preferable to provide notches on both edges of the two rows of land portions.

  In the present invention, the main groove is a groove provided with a tread wear indicator (JIS D4230). As other grooves, the narrow groove is a groove having a groove width of 0.1 mm to 1.5 mm, the sipe is a groove having a groove width of 0.4 mm to 1.6 mm, and the lug groove is a groove width exceeding 1.5 mm. However, the groove is narrower than the main groove.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a tread pattern of a pneumatic tire according to an embodiment of the present invention, FIG. 2 shows a sipe of a land portion located on the most shoulder side, and FIG. 3 shows a tire tread when the sipe of FIG. The plan view shape and the plan view shape at the sipe bottom are shown, and FIGS. 4 to 6 show the land portion located closest to the center of the tread. The pneumatic tire of the present embodiment is designated with the tire front and back mounting orientation when the vehicle is mounted, and the vehicle outer side is indicated by OUT and the vehicle inner side is indicated by IN.

  As shown in FIG. 1, four main grooves 1a, 1b, 1c, and 1d extending in the tire circumferential direction are sequentially formed in the tread portion T from the vehicle inner side to the vehicle outer side, and these main grooves 1a to 1d form five rows. Land portions 10, 20, 30, 40, and 50 are partitioned. That is, the land portion 10 is located at the shoulder portion inside the vehicle, the land portion 20 is located between the main grooves 1a and 1b, the land portion 30 is located between the main grooves 1b and 1c, and the land portion 40 is located between the main grooves 1c. , 1d, and the land portion 50 is located on the shoulder portion outside the vehicle. The main grooves 1a to 1d may all have the same groove width. For example, the main grooves 1c and 1d on the vehicle outer side are made thicker than the main grooves 1a and 1b on the vehicle inner side, or the main grooves on the shoulder side are used. It is possible to make 1a and 1d thicker than the main grooves 1c and 1d on the tread center side.

  A circumferential auxiliary groove 14 extending in the tire circumferential direction is provided in the land portion 10 located on the most shoulder side inside the vehicle. Furthermore, in the land portion 10, a plurality of lug grooves 11 extending in the tire width direction and sipes 12 extending in the tire width direction are alternately arranged along the tire circumferential direction. The lug groove 11 extends in the tire width direction and communicates with the circumferential auxiliary groove 14. As shown in FIG. 2, the sipe 12 has one end terminating in the land portion 10 and the other end communicating with the circumferential auxiliary groove 14. The sipe 12 is generally straight on the tire tread when new, but has a three-dimensional structure that becomes a wave shape toward the bottom of the sipe. As shown in FIG. The visual shape 12a crosses the planar view shape 12b when worn.

  In the sipe 12, the sipe length L2 when worn is set to be substantially the same as the sipe length L1 when new. Here, the new sipe length L1 is a distance between sipe ends in a plan view when new. On the other hand, the sipe length L2 at the time of wear is a distance between sipe ends in a plan view shape at the time of wear.

  In the sipe 12, the sipe path length M2 when worn is set longer than the sipe path length M1 when new. Here, the new sipe path length M1 is a distance between sipe ends in a plan view when new. On the other hand, the sipe path length M2 at the time of wear is a distance between sipe ends in a plan view shape at the time of wear.

  A plurality of lug grooves 21 extending in the tire width direction and a plurality of sipes 22 extending in the tire width direction are provided on the land portion 20 sandwiched between the two main grooves 1a and 1b that are inside the vehicle when the vehicle is mounted. Alternatingly arranged along the direction. One end of each of the lug groove 21 and the sipe 22 terminates in the land portion 20, and the other end communicates with the main groove 1a.

  As shown in FIGS. 4 to 6, a plurality of notch portions 31 each having a triangular curved surface 31 a in plan view are spaced at both edges of the land portion 30 located closest to the center of the tread in the tire circumferential direction. Is formed. The curved surfaces 31a of the cutout portions 31 are formed so as to be in contact with the tread surface of the land portion 30 without having a ridgeline at one side of the triangle. Further, a protrusion 32 is formed at a position adjacent to the deepest part of each notch 31 so as to protrude into the main grooves 1b and 1c.

  The land portion 40 sandwiched between the two main grooves 1c and 1d, which are outside the vehicle when the vehicle is mounted, has a plurality of pieces extending from the main groove 1c on the tread center side toward the vehicle outer side and terminating in the land portion 40. Lug grooves 41 are provided at intervals in the tire circumferential direction. Further, in the land portion 40, the circumferential narrow groove 42 that intermittently extends in the tire circumferential direction without communicating with the lug groove 41 and forms a wave shape or a zigzag shape, and the lug groove 41 in the tire width direction. A plurality of width-direction narrow grooves 43 that extend and communicate with the circumferential narrow grooves 42 without being communicated with the circumferential narrow grooves 42 are provided.

  A circumferential auxiliary groove 54 extending in the tire circumferential direction is provided in the land portion 50 located on the most shoulder side on the vehicle outer side. Furthermore, in the land portion 50, a plurality of lug grooves 51 extending in the tire width direction and a plurality of sipes 52 extending in the tire width direction are alternately arranged along the tire circumferential direction. Each lug groove 51 is connected to a sipe 53 extending from the tip thereof toward the center of the tread. One end of the sipe 52 terminates in the land portion 50, and the other end communicates with the main groove 1d. Similar to the sipe 12 described above, the sipe 52 has a linear shape on the tire tread surface when it is new, but has a three-dimensional structure that becomes a waveform as it goes toward the bottom of the sipe. The visual shape crosses the planar shape when worn. In the sipe 52, as in the sipe 12, the sipe length L2 at the time of wear is set to be substantially the same as the sipe length L1 at the time of new, and the sipe path length M2 at the time of wear is the sipe path length when new. It is set longer than M1.

  In the pneumatic tire having the above-described tread pattern, a plurality of cutout portions 31 each having a triangular curved surface 31a in plan view are provided on both edge portions of the land portion 30 located on the most tread center side, and these cutout portions are provided. The curved surface 31a of 31 is formed at one side of the triangle so as to be in contact with the tread surface of the land portion 30 without having a ridgeline, thereby generating in the main grooves 1b and 1c without lowering the steering stability. Air column resonance can be reduced. That is, the main grooves 1b and 1c extending continuously in the tire circumferential direction are likely to generate air column resonance sound having a frequency of about 800 to 1500 Hz, but are provided with a plurality of cutout portions 31 connected to the main grooves 1b and 1c. Thus, the effect of reducing the air column resonance is obtained. In addition, by forming the curved surface 31a of the notch 31 so as to be in contact with the tread surface of the land part 30 without having a ridgeline at one side of the triangle, the occurrence of uneven wear starting from the notch 31 is generated. Can be suppressed.

  Here, the width W1 of the notch 31 in the tire axial direction is set to a range of 20% to 50%, preferably 30% to 35% of the width W0 of the land portion 30, and the depth of the notch 31 is set. The length D1 is set in the range of 10% to 125% of the effective groove depth D0 of the main grooves 1b and 1c, preferably in the range of 50% to 125%, and the length P1 of the notch 31 in the tire circumferential direction is The notch 31 is set in the range of 10% to 50%, preferably in the range of 30% to 45% of the pitch length P0 in the tire circumferential direction. If the dimension of the notch 31 is below the lower limit, the effect of reducing the air column resonance is reduced. Conversely, if the upper limit is exceeded, the steering stability is lowered, and uneven wear is likely to occur. The effective groove depth D0 of the main grooves 1b and 1c is the depth from the tread surface to the wear indicator 2.

  In particular, when the protrusion 32 protruding into the main grooves 1b and 1c is provided at a position adjacent to the deepest portion of the notch 31, the air column resonance can be more effectively reduced. The protrusion 32 may have a triangular pyramid shape as shown in FIG. 4 or another shape. For example, as shown in FIG. 7, the protrusion 32 may be formed by extending a wall surface 31b intersecting the curved surface 31a of the notch 31 into the main grooves 1b and 1c.

  In the pneumatic tire described above, the lug groove 41, the circumferential narrow groove 42, and the width narrow groove 43 are mixed in the land portion 40 sandwiched between the two main grooves 1c and 1d that are outside the vehicle when the vehicle is mounted. Thus, braking performance and turning performance on the wet road surface can be ensured based on the edge effect of these grooves 41 to 43. In other words, the grooves 41 to 43 act to absorb the moisture on the road surface and simultaneously capture the road surface with edges that extend in multiple directions. Moreover, since the lug groove 41, the circumferential narrow groove 42, and the width narrow groove 43 are provided in the land portion 40 to reduce the rigidity of the land portion 40, an impact at the time of grounding is effectively reduced, so that excellent quietness is achieved. Can demonstrate its sexuality. In addition, the lug groove 41 is opened to the main groove 1c on the tread center side and is not in communication with the main groove 1d on the vehicle outer side, and the lug groove 41, the circumferential narrow groove 42, and the width narrow groove 43 are connected to each other. Since it is not connected, it is possible to suppress an excessive decrease in rigidity in the land portion 40 and improve steering stability on the dry road surface and the wet road surface. In particular, cornering power at low loads can be secured, and steering stability (rear tire stability) on dry roads can be improved.

  Further, the land portions 10 and 50 located on the most shoulder side are provided with a plurality of sipes 12 and 52 extending in the tire width direction and terminating at one end in the land portion. While making L2 substantially the same as the sipe length L1 when new, the sipe path length M2 when worn is longer than the sipe path length M1 when worn, and the plan view shape when worn is a flat surface when worn. The shape of the shoulder portion, which increases the load during cornering, is arranged by placing the sipe 12, 52 having a three-dimensional structure on the land portions 10, 50 located on the most shoulder side in this way. The cornering performance and braking performance can be improved. In addition, since the sipe path length M2 becomes longer as the wear progresses, it is possible to suppress a decrease in wet performance during wear.

  The land portion 10 is provided with a lug groove 11 in addition to the sipe 12, and the land portion 50 is provided with a lug groove 51 and a sipe 53 having a two-dimensional structure in addition to the sipe 52. Or, by combining the sipe 53 having a two-dimensional structure with the sipe 12, 52 having a three-dimensional structure, the rigidity of the land portions 10 and 50 can be appropriately adjusted.

  The sipe path length M2 at the time of 40% wear of the sipe 12, 53 is set to be in the range of 102% to 150%, more preferably in the range of 105% to 130% of the sipe path length M1 when new. If the sipe path length M2 at 40% wear is less than 102% of the new sipe path length M1, the effect of suppressing the reduction in wet performance at the time of wear becomes insufficient. In some cases, the land portion is easily damaged.

  In the embodiment described above, the configuration of each land portion partitioned into tread portions has been described in detail. However, in the present invention, as long as a predetermined notch portion is provided at an edge portion facing the main groove of at least one row of land portions. The configuration of the other land portions is not particularly limited. Of course, the present invention is not limited to tires in which the tire front and back mounting directions are designated.

  For example, as shown in FIG. 8, in a pneumatic tire in which four main grooves 1a to 1d extending in the tire circumferential direction are provided in a tread portion T and five rows of land portions 10 to 50 are partitioned by these main grooves, While notches 31 are provided on both edges of the land 30 located on the center side of the tread, rib structures are used for the other land 10, 20, 40, and 50, and arbitrary grooves are arranged. can do.

  As shown in FIG. 9, in the pneumatic tire in which four main grooves 1 a to 1 d extending in the tire circumferential direction are provided in the tread portion T and five rows of land portions 10 to 50 are partitioned by these main grooves. While providing notches 31 at both edges of the two rows of land portions 20 and 40 sandwiched between the main grooves 1b and 1c on the center side and the main grooves 1a and 1d on the shoulder side, the other land portions As for 10, 30, and 50, a rib structure can be adopted or an arbitrary groove can be arranged.

  In the pneumatic tire having the tread pattern shown in FIG. 8 or FIG. 9 with a tire size of 215 / 55R17, various dimensions (W1 / W0, D1 / D0, P1 / P0) of notches provided in the land portion Different tires of Examples 1 to 4 were produced.

  For comparison, a pneumatic tire (conventional example) provided with four main grooves 1 extending in the tire circumferential direction in the tread portion T as shown in FIG. 10 and a tire circumferential direction in the tread portion T as shown in FIG. A pneumatic tire (Comparative Example 1) having three main grooves 1 extending in the center and a plurality of lug grooves 61 in two land rows in the center of the tread, and a tire circumference in the tread T as shown in FIG. A pneumatic tire (Comparative Example 2) having four main grooves 1 extending in the direction and a plurality of lug grooves 71 in the land portion at the center of the tread was prepared.

  These tires were evaluated for air column resonance, steering stability, and uneven wear resistance by the following evaluation methods, and the results are shown in Table 1.

Air column resonance:
The test tire is mounted on a wheel with a rim size of 17 × 7.0J and mounted on a rear-wheel drive vehicle with a displacement of 3000 cc. The air pressure is 220 kPa and the frequency of 800 to 1000 Hz generated when the test road surface is driven at a speed of 60 km / h. The column resonance sound was measured beside the test road surface. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. It means that there are few air column resonance sounds, so that this index value is large.

Steering stability:
The test tire was assembled on a wheel with a rim size of 17 × 7.0 J and mounted on a rear-wheel drive vehicle with a displacement of 3000 cc, and the steering stability was sensory evaluated on a dry road surface at an air pressure of 220 kPa. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the steering stability.

Uneven wear resistance:
The test tire was assembled on a wheel with a rim size of 17 × 7.0 J and mounted on a rear-wheel drive vehicle with a displacement of 3000 cc. After running on a general road for 8000 km with an air pressure of 220 kPa, the amount of uneven wear at each land portion was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the uneven wear resistance.

  As is apparent from Table 1, the tires of Examples 1 to 4 were able to reduce air column resonance noise while maintaining good steering stability and uneven wear resistance as compared with the conventional example. On the other hand, although the tires of Comparative Examples 1 and 2 were found to have an effect of reducing air column resonance noise, the steering stability and uneven wear resistance were reduced accordingly.

It is an expanded view which shows the tread pattern of the pneumatic tire which consists of embodiment of this invention. It is sectional drawing which shows the sipe of the land part located in the most shoulder side in FIG. It is explanatory drawing which shows the planar view shape in the tire tread surface at the time of the new article of the sipe of FIG. 2, and the planar view shape in the sipe bottom. It is a perspective view which shows the land part most located in the tread center side in FIG. It is a top view which shows the land part most located in the tread center side in FIG. It is a side view which shows the land part most located in the tread center side in FIG. It is a perspective view which shows the modification of the notch part formed in a land part in this invention. It is a top view which shows roughly the tread pattern of the pneumatic tire which consists of other embodiment of this invention. It is a top view which shows roughly the tread pattern of the pneumatic tire which consists of further another embodiment of this invention. It is a top view which shows roughly the tread pattern of the pneumatic tire of a prior art example. 3 is a plan view schematically showing a tread pattern of a pneumatic tire of Comparative Example 1. FIG. 6 is a plan view schematically showing a tread pattern of a pneumatic tire of Comparative Example 2. FIG.

Explanation of symbols

1a, 1b, 1c, 1d Main groove 10, 20, 30, 40, 50 Land portion 11, 21, 41, 51 Lug groove 12, 22, 52, 53 Sipe 31 Notch portion 31a Curved surface 31b Wall surface 42 Groove 43 Width direction narrow groove T Tread part

Claims (7)

  In a pneumatic tire in which a plurality of main grooves extending in the tire circumferential direction are provided in the tread portion, and a plurality of rows of land portions are partitioned by the main grooves, a plan view is provided at an edge portion facing the main grooves of at least one row of land portions. A plurality of cutout portions having a triangular curved surface are provided, and the curved surfaces of these cutout portions are formed so as to be in contact with the tread surface of the land portion without having a ridgeline at one side of the triangle. And pneumatic tires.   2. The pneumatic tire according to claim 1, wherein a width of the notch portion in a tire axial direction is 20% to 50% of a width of a land portion.   The pneumatic tire according to claim 2, wherein the depth of the notch is 10% to 125% of the effective groove depth of the main groove.   The pneumatic tire according to claim 3, wherein a length of the notch in the tire circumferential direction is 10% to 50% of a pitch length of the notch in the tire circumferential direction.   The pneumatic tire according to claim 1, wherein a protrusion protruding into the main groove is provided at a position adjacent to the deepest portion of the cutout portion.   In a pneumatic tire in which four main grooves extending in the tire circumferential direction are provided in the tread portion, and five rows of land portions are defined by these main grooves, the above-mentioned cuts are made at both edge portions of the land portion located closest to the center of the tread. The pneumatic tire according to any one of claims 1 to 5, wherein a notch is provided.   In a pneumatic tire in which four main grooves extending in the tire circumferential direction are provided in the tread portion, and five rows of land portions are defined by these main grooves, the main groove is sandwiched between the main groove on the center side of the tread and the main groove on the shoulder side. The pneumatic tire according to any one of claims 1 to 5, wherein the notches are provided at both edge portions of two rows of land portions.

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