JP2012056464A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire having a tread pattern configured to improve motion performance or wear resistance performance of the tire by preventing deterioration in rigidity of a small block, and to improve calmness by dispersing a frequency generated from a transverse groove.SOLUTION: The tire has a tread 12 including a circumferential main groove 14 formed in the tire circumferential direction, a land part line 16 defined by the circumferential main groove 14, a plurality of transverse sipes 22 provided in the land part line 16 so as to communicate with the circumferential main groove 14 and to be separated at different intervals in the tire circumferential direction; a plurality of small blocks 24 differed in pitch length, which are defined by the adjacent transverse sipes 22 in the land part line 16, and transverse grooves 30 formed respectively in the plurality of small blocks 24 and opened to the circumferential main groove 14. The transverse grooves 30 are formed so that the acute angle-side angle β to the tire circumferential direction is larger in the transverse groove 30 formed in the small block 24 having a shorter pitch length than in the transverse groove 30 formed in the small block 24 having a longer pitch length.

Description

  The present invention relates to a tire, and more specifically, to a tire characterized by a tread pattern.

  Conventionally, in order to improve drainage performance and snow / ice performance, tires in which a large number of lateral grooves and lateral sipes are provided in the direction intersecting with the circumferential main grooves formed in the tire circumferential direction on the tread are widely known (the following patents) Reference 1).

JP2010-018155

  FIG. 5 is a diagram illustrating an example of a tread pattern of a tire. As shown in the figure, the tread has four circumferential main grooves 114 formed in the tire circumferential direction, and five rows of land portions (one central region land row 116, two middle region land portions 118). Two rows of shoulder region land rows 120) are formed. Each land portion row is provided with a horizontal groove or a horizontal sipe in a direction intersecting with the circumferential main groove 114.

  Paying attention to the central region land portion row 116 including the tire equatorial plane CL among the five row portion rows, a plurality of lateral sipes 122 formed in a direction intersecting the circumferential main groove 14 are provided in the circumferential direction. A plurality of small blocks 124 defined by adjacent horizontal sipes 122 are formed along the circumferential direction. In order to improve drainage performance and ice / snow performance, each small block 124 is provided with a lateral groove 130 whose both ends open to the circumferential main groove 114.

  Further, in order to disperse the frequency generated from the small blocks 124 and improve the quietness, five small blocks 124-1, 124-2, 124 having five pitch lengths L1 to L5 as shown in the figure. −3, 124-4, and 124-5 are formed.

  Since the horizontal sipe 122 and the horizontal groove 130 are formed so as to form a predetermined angle with respect to the tire circumferential direction (approximately 30 ° on the acute angle side), acute angles 126 and 132 are formed in the small block 124. In particular, in the small block 124 with a short pitch length, the rigidity is significantly reduced in the acute angle portions 126 and 132, and the rigidity of the small block 124 as a whole is lowered, and the tire motion performance and wear resistance are deteriorated. It was.

  In addition, the small blocks 124 change the pitch length to improve quietness. However, since the horizontal grooves 130 of each small block 124 are formed at a constant angle with respect to the circumferential direction, The generated frequencies were concentrated on one point, leaving room for improvement in improving quietness.

  Therefore, the present invention improves the motion performance and wear resistance performance of the tire by preventing a decrease in the rigidity of the small block, even when forming a horizontal sipe or a horizontal groove to improve drainage performance or snow and snow performance, An object is to improve the quietness by dispersing the frequency generated from the lateral groove.

  The tire according to claim 1 of the present invention includes a circumferential main groove formed in the tire circumferential direction, a land portion row defined by the circumferential main groove, and the circumferential main groove in the land portion row. A plurality of horizontal sipes that communicate with each other at different intervals in the tire circumferential direction, a plurality of small blocks having different pitch lengths defined by the adjacent horizontal sipes in the land portion row, and the plurality of small blocks The horizontal grooves formed in the small blocks having a short pitch length are formed in the small blocks having a longer pitch length. Compared with the said lateral groove, it forms so that the angle of the acute angle side with respect to the tire circumferential direction may become large.

  According to the tire of the first aspect of the present invention, the tire includes a plurality of small blocks having different pitch lengths partitioned by adjacent horizontal sipes in the land portion row, and each of the plurality of small blocks has an opening in the circumferential main groove. When forming the transverse groove, the lateral groove formed in the small block having a shorter pitch length has a larger acute angle with respect to the tire circumferential direction than the lateral groove formed in the small block having a longer pitch length.

  Therefore, even when an acute angle portion is formed by a lateral groove in a small block, the acute angle portion formed in a small block having a short pitch length is more acute than the acute angle portion formed in a small block having a long pitch length. Since the angle of the portion is increased, it is possible to suppress a decrease in rigidity in a small block having a short pitch length. Thereby, the motion performance and wear resistance performance of the tire can be improved.

  Further, since the horizontal groove of each small block is formed at various angles according to the pitch length of the small block, the frequency generated from the horizontal groove is dispersed without concentrating on one point. Thereby, silence can be improved.

  According to a second aspect of the present invention, in the tire according to the first aspect, the lateral sipes are spaced so that an angle with respect to a tire circumferential direction is constant regardless of a pitch length of the small blocks. Or when the angle with respect to the tire circumferential direction changes with respect to the pitch length of the small block, the amount of the angle change is smaller than the amount of the angle change of the lateral groove.

  According to the tire of the second aspect of the present invention, in short, the angle of the horizontal sipe with respect to the tire circumferential direction is made substantially constant regardless of the pitch length of the small block. By setting the angle so as to be small, it is possible to prevent the end portion of the small block from becoming too acute. Thereby, the fall of the rigidity of a small block can be prevented more and the exercise | movement performance and abrasion resistance performance of a tire can be improved more.

  The tire according to claim 3 of the present invention is characterized in that, in the tire according to claim 1 or 2, the lateral groove is formed so as to be raised at both ends thereof.

  According to the tire of the third aspect of the present invention, both end portions of the lateral groove are raised. Accordingly, even when an acute angle portion is formed by a lateral groove in the small block, it is possible to prevent a decrease in rigidity of the acute angle portion of the small block. Thereby, the motion performance and wear resistance performance of the tire can be further improved.

  According to a fourth aspect of the present invention, in the tire according to any one of the first to third aspects, the lateral sipe is formed so as to be raised at both ends thereof. .

  According to the tire of the fourth aspect of the present invention, both ends of the horizontal sipe are raised. Therefore, even when an acute angle portion is formed by a horizontal sipe in the small block, it is possible to prevent a decrease in rigidity of the acute angle portion of the small block. Thereby, the motion performance and wear resistance performance of the tire can be further improved.

  The tire according to claim 5 of the present invention is the tire according to any one of claims 1 to 4, wherein the land portion row is a central region land portion row arranged in the center in the tire width direction. It is characterized by that.

  According to the tire according to claim 5 of the present invention, since the configuration according to any one of claims 1 to 4 is provided with respect to the central region land portion row arranged in the center in the tire width direction, It is possible to effectively improve the tire performance, wear resistance and quietness of the tire.

  As described above, according to the tire of the present invention, even when a horizontal sipe or a horizontal groove is formed in order to improve drainage performance or ice / snow performance, the reduction in rigidity of the small block is prevented and In addition to improving the wear resistance, it is possible to improve the quietness by dispersing the frequencies generated from the lateral grooves.

It is a figure showing a tread pattern of a tire of an embodiment concerning the present invention. It is a figure which expands and shows the center area | region of FIG. It is sectional drawing in the 3-3 line of FIG. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. It is a figure which shows the tread pattern of the tire of a comparative example.

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

  FIG. 1 is a view showing a tread pattern of a tire according to an embodiment of the present invention. FIG. 2 is an enlarged view of the central region of FIG. The tire 10 of the embodiment according to the present invention is, for example, a pneumatic radial tire. In the tread 12, a plurality of, for example, four circumferential main grooves 14 as shown in FIG. 1 are formed symmetrically with respect to the tire equatorial plane CL, and five land portions are formed.

  One of the five land portion rows is a central region land portion row 16 that includes the tire equatorial plane and is disposed at the center in the tire width direction. On both sides of the central area land row 16, an intermediate area land portion row 18 and a shoulder region land portion row 20 are formed in the adjacent order.

  Each land row is provided with a plurality of lateral sipes and lateral grooves that contribute to drainage performance and ice / snow performance along the tire circumferential direction.

  Specifically, in the central region land portion row 16, a plurality of lateral sipes 22 are spaced apart in the tire circumferential direction, and small blocks 24 defined by the adjacent lateral sipes 22 are formed along the plurality of tire circumferential directions. Yes. As shown in the figure, each lateral sipe 22 communicates with the circumferential main groove 14 and is formed so as to be inclined with respect to the tire circumferential direction (lower right in the figure).

  The angle α of each lateral sipe 22 with respect to the tire circumferential direction (angle on the acute angle side, hereinafter simply referred to as “inclination angle”) α is constant (there may be a slight difference as described later), and each lateral sipe 22 Are formed parallel to each other. Since each small block 24 is partitioned by the horizontal sipe 22 having the inclination angle α, each small block 24 is formed with two acute angle portions (first acute angle portions) 26 and two obtuse angle portions 28. The corner of the acute angle portion 26 is cut as shown in the figure.

  The intervals at which the horizontal sipes 22 are spaced in the central region land portion row 16 are not uniform, and as shown in the figure, for example, five kinds of small blocks 24-1 and 24-2 having five kinds of pitch lengths L1 to L5. , 24-3, 24-4, and 24-5. The pitch length has a relationship of L1> L2> L3> L4> L5. As shown in the figure, the five kinds of small blocks 24 are adjacent to the small block 24-2 having the pitch length L1 and the small block 24-2 having the pitch length L2, and the small block 24-2 having the pitch length L2. A small block 24-3 having a length L3 is adjacent to the small block 24-3 having a pitch length L3, and a small block 24-4 having a pitch length L4 is adjacent to the small block 24-4 having a pitch length L4. The small blocks 24-5 are adjacent to each other, the small blocks 24-5 having the pitch length L5 are adjacent to the small blocks 24-1 having the pitch length L1, and are arranged in the order of arrangement. In addition, you may arrange | position the 5 types of small blocks 24-1, 24-2, 24-3, 24-4, and 24-5 at random.

  Each small block 24 is formed with one lateral groove 30. The lateral groove 30 is formed at the center so as to equally divide the small blocks. Further, the lateral groove 30 is open to the circumferential main groove 14 at both ends, and is inclined in the same direction as the lateral sipe 22. Therefore, the second acute angle portion 32 is formed at two locations by the lateral groove 30 in each small block 24.

  Each small block 24 is formed with a longitudinal sipe 34 along the tire equatorial plane CL. One side of the vertical sipe 34 communicates with the lateral groove 30, while the other side terminates in the small block 24.

  The lateral grooves 30 of each small block 24 have acute angles (hereinafter simply referred to as “lateral groove angles”) β1, β2, β3, β4, and β5 with respect to the tire circumferential direction. The pitch lengths L1, L2, and L3 of the small blocks 24 are , L4, and L5.

  Specifically, the transverse groove angle of the transverse groove 30 formed in the small block 24-1 having the pitch length L1 is β1, the transverse groove angle of the transverse groove 30 formed in the small block 24-2 having the pitch length L2 is β2, and the pitch length L3. The lateral groove angle of the lateral groove 30 formed in the small block 24-3 is β3, and the lateral groove angle of the lateral groove 30 formed in the small block 24-4 having the pitch length L4 is β4 and formed in the small block 24-5 having the pitch length L5. When the horizontal groove angle of the horizontal groove 30 is β5, there is a relationship of β1 <β2 <β3 <β4 <β5. That is, the lateral groove 30 formed in a small block with a short pitch length is formed so that the lateral groove angle β is larger than the lateral groove 30 formed in a small block with a long pitch length. Therefore, the angle of the second acute angle portion 32 of the small block 24 with a short pitch length is larger than the angle of the second acute angle portion 32 of the small block 24 with a long pitch length.

  FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. That is, it is a diagram showing a cross-sectional shape of the lateral groove 30 of the small block 24 of the central region land portion row 16.

  The lateral groove 30 of each small block 24 is raised at the both end sides. The ratio of the bottom raised portion 36 to the entire horizontal groove 30 (ratio of the length of the bottom raised portion 36 to the entire length of the horizontal groove 30) is about 40%. The ratio of the depth of the bottom raised portion 36 to the depth near the center of the lateral groove 30 is about 60%.

  4 is a cross-sectional view taken along line 4-4 of FIG. That is, it is a diagram showing a cross-sectional shape of the horizontal sipe 22 of the central region land portion row 16.

  The horizontal sipe 22 of each small block 24 is raised at both ends. The ratio of the raised portion 38 to the entire horizontal sipe 22 (the ratio of the length of the raised portion 38 to the entire length of the horizontal sipe 22) is about 43%. The ratio of the depth of the raised portion 38 to the depth near the center of the horizontal sipe 22 is about 60%.

  As shown in FIG. 1, the intermediate region land row 18 is divided into a plurality of small blocks by lateral grooves that are spaced apart in the tire circumferential direction. The small blocks of the intermediate area land portion row 18 also have different pitch lengths, and have the same pitch length as the small blocks 30 of the adjacent central region land portion row 16. Grooves and sipes for improving drainage performance and ice / snow performance are formed in each small block of the intermediate region land section row 18. Since these shapes are the same as those of the tire shown in FIG. 5 and are not involved in the present invention, further explanation is omitted.

  Each shoulder land row 20 is also divided into a plurality of small blocks by lateral grooves spaced in the tire circumferential direction. The small blocks of the shoulder land rows 20 have different pitch lengths and have the same pitch length as the small blocks of the adjacent intermediate region land rows 18 (that is, the small blocks 30 of the central region land row 16). Grooves and sipes for improving drainage performance and ice / snow performance are also formed in each small block of the shoulder region land portion row 20. Since those shapes are also the same as those of the tire shown in FIG. 5 and are not involved in the present invention, further explanation is omitted.

(Function)
In the central region land portion row 16, the transverse groove angle β of the transverse groove 30 formed in the small block 24 with a short pitch length is set to be larger than the transverse groove angle β of the transverse groove 30 formed in the small block 24 with a long pitch length. Thus, the angle of the second acute angle portion 32 of the small block 30 having a short pitch length is larger than the angle of the second acute angle portion 32 of the small block 24 having a long pitch length.

  The small block 24 with a short pitch length originally has lower rigidity than the small block 24 with a long pitch length. However, when the lateral groove 30 is formed in the small block 24 with a short pitch length, the small block 24 has a lower rigidity than the small block 24 with a long pitch length. The rigidity is further reduced. Therefore, the angle of the second acute angle portion 32 of the small block 24 with a short pitch length is set to be larger than the angle of the second acute angle portion 32 of the small block 24 with a long pitch length. Thereby, the fall of the rigidity of the small block 24 with a short pitch length can be suppressed.

  In other words, even when the second acute angle portion 32 is formed in the small block 24 by the lateral groove 30, the pitch length of the second acute angle portion 32 formed in the small block 24 having a shorter pitch length is larger. Since the angle of the acute angle portion is larger than that of the second acute angle portion 32 formed in the long small block 24, it is possible to suppress a decrease in rigidity in the small block 24 having a short pitch length. Thereby, the motion performance and wear resistance performance of the tire can be improved.

  Further, since the horizontal groove 30 of each small block 24 is formed with five kinds of angles β1, β2, β3, β4, and β5 according to the pitch length of the small block 24, the frequency generated from the horizontal groove 30 is concentrated on one point. Disperse without. Thereby, silence can be improved. Note that the five types of pitch lengths of the small blocks are examples, and the number is not limited as long as there are a plurality of types.

  In the central region land portion row 16, the inclination angle α of the horizontal sipe 22 is made constant regardless of the pitch length of the small blocks 24, so that the first angle of the small block 24 is set by setting the inclination angle α to an appropriate angle in advance. It is possible to prevent the acute angle portion 26 from becoming too acute. Thereby, the fall of the rigidity of the small block 24 can be prevented more and the exercise | movement performance and abrasion resistance performance of a tire can be improved more.

  It should be noted that the inclination angle α of the horizontal sipe 22 is not constant, and, for example, the inclination angle α of the horizontal sipe 22 of the small block 24 having a short pitch length is set to be larger in the horizontal direction of the small block 24 having a longer pitch length. Although it may be set larger than the inclination angle α of the sipe 22, it is desirable that the amount of change in the inclination angle α of the horizontal sipe 22 is smaller than the amount of change in the angle of the horizontal groove 30. If the change in the inclination angle α of the horizontal sipe 22 is equal to or greater than the change in the angle of the horizontal groove 30, the first acute angle portion 26 and the second acute angle portion 32 become acute angles in the small block 24 having a particularly long pitch length. This is because the rigidity of the small block 24 is lowered.

  The lateral groove 30 of each small block 24 is raised at the both end sides. Thereby, it is possible to suppress a decrease in rigidity at the second acute angle portion 32 of the small block 24.

  The horizontal sipe 22 of each small block 24 is raised at both ends. Thereby, it is possible to suppress a decrease in rigidity at the first acute angle portion 26 of the small block 24.

  The transverse groove angle β is made different for the transverse groove 30 of the small block 24 in the central region land portion row 16, but the intermediate region land portion row 18 and the shoulder region land portion row 20 other than the central region land portion row 16 are small. You may make it make a horizontal groove angle differ regarding the horizontal groove of a block. Nevertheless, the tire motion performance, wear resistance performance and quietness performance can be further improved by making the lateral groove angle β different with respect to the lateral groove 30 of the small block 24 in the central region land portion row 16 having a large ground contact area.

(Test example)
A tire according to the example (FIG. 1) and a tire according to the comparative example (FIG. 5) were prototyped and evaluated for block rigidity, motion performance, wear resistance performance, snow and snow performance, and quietness. The results are shown in Table 1. The numerical value shown in the table is an index when the tire of the comparative example is 100, and the larger the numerical value, the better the performance.

  In FIG. 5, 110 is a tire, 112 is a tread, 114 is a circumferential main groove, 116 is a central region land row, 118 is an intermediate region land row, 120 is a shoulder region land row, 122 is a lateral sipe, Reference numeral 124 denotes a small block, 126 denotes an acute angle portion, 130 denotes a lateral groove, 132 denotes an acute angle portion, and 134 denotes a longitudinal sipe.

  The block stiffness increased by 10% compared to the tire of the comparative example. This is considered to be caused by the improved rigidity of the small blocks 24 having a particularly short pitch length in the central region land portion row 16.

  The kinematic performance and wear resistance increased by 10% compared to the tire of the comparative example. This is considered to be due to the improved block rigidity.

  The snow and snow performance was equivalent to the tire of the comparative example. This means that in the tire according to the present embodiment, both end sides of the lateral groove 30 are raised in the central region land portion row 16, but the ice / snow performance is hardly affected.

  The quietness increased by 30% compared to the tire of the comparative example. As described above, by setting the horizontal grooves 30 of the small blocks 24 in the central region land portion row 16 to have five kinds of angles, the frequency generated from the horizontal grooves 30 is dispersed without concentrating on one point, so that silence is improved. It is considered a thing.

10 Tire 12 Tread 14 Circumferential Main Groove 16 Central Region Land Part Row (Land Part Row)
18 Middle region land portion row 20 Shoulder region land portion row 22 Horizontal sipe 24 Small block 26 First acute angle portion 28 Obtuse angle portion 30 Horizontal groove 32 Second acute angle portion 34 Vertical sipe 36 Bottom raised portion 38 Bottom raised portion

Claims (5)

A circumferential main groove formed in the tire circumferential direction;
A land portion row partitioned by the circumferential main groove;
A plurality of horizontal sipes communicating with the circumferential main grooves in the land portion row and spaced apart at different intervals in the tire circumferential direction;
A plurality of small blocks having different pitch lengths partitioned by the adjacent horizontal sipes in the land portion row;
A lateral groove formed in each of the plurality of small blocks and opening in the circumferential main groove;
Having a tread with
The lateral groove formed in the small block having a shorter pitch length is formed so that the angle on the acute angle side with respect to the tire circumferential direction is larger than the lateral groove formed in the small block having a longer pitch length. A characteristic tire.   The horizontal sipes are spaced so that the angle with respect to the tire circumferential direction is constant regardless of the pitch length of the small block, or the angle with respect to the tire circumferential direction changes with respect to the pitch length of the small block. The tire according to claim 1, wherein the amount of change in angle is smaller than the amount of change in angle of the lateral groove.   The tire according to claim 1 or 2, wherein the lateral groove is formed so as to be raised at both ends thereof.   The tire according to any one of claims 1 to 3, wherein the lateral sipe is formed to be raised at both ends thereof.   The tire according to any one of claims 1 to 4, wherein the land portion row is a central region land portion row disposed in the center in the tire width direction.