JP5184116B2 - studless tire - Google Patents

Description

  The present invention relates to a studless tire having an odd number of rows of blocks arranged in a circumferential direction on a tread surface and arranged in the width direction, and in particular, steering for a minute steering angle while ensuring traction performance necessary for running on ice and snow. It relates to things that improve stability.

  In studless tires, it is necessary to ensure traction performance and braking performance in snowy and snowy driving as well as to improve drainage performance.Therefore, the tread pattern has multiple rows of blocks arranged in the circumferential direction along the tire width direction. Each block row is known in which transverse grooves are arranged so that the number of blocks is the same (see, for example, Patent Document 1).

FIG. 1 is a development view showing an example of such a tire tread pattern. A total of five block rows 91, 92, 93, 94, and 95 are arranged on the tread surface 90 of the tire. The number of blocks 99 to be configured is the same. Reference numeral 97 denotes a circumferential groove, and 98 denotes a lateral groove.
Japanese Patent Laid-Open No. 08-080713

  However, when block rows consisting of all the same number of blocks as in the past are arranged in the tire width direction, the traction performance and braking performance on ice and snow will improve as the number of blocks arranged in the circumferential direction increases. However, since the tread rigidity decreases, the steering stability deteriorates. On the other hand, if the number of blocks arranged in the circumferential direction is reduced, the tread rigidity increases and the steering stability can be improved, but the traction performance and braking performance are sacrificed.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a studless tire capable of achieving both steering stability and traction performance and braking performance on ice and snow. To do.

<1> is a studless tire in which an odd number of block rows formed by arranging blocks in the circumferential direction on the tread surface and arranged in the width direction.
Among these block strings, when the block string located in the center in the arrangement order is called a center block string and the block strings located on both outer sides of the center block string are called second block strings, the second block with respect to the center block string The column has 1.5 to 2 times the number of blocks ,
When a block row located on both outer sides of the second block row is called a third block row, the number of blocks in the third block row and the center block row is the same, which is a studless tire.

<2> is a studless tire characterized in that, in <1> , a part of the tire circumferential direction side end of the block constituting the center block row protrudes in the tire circumferential direction.

<3> is a studless tire according to <2> , wherein a pin sipe that does not communicate with any groove is disposed in a portion of the blocks constituting the center block row that protrudes in the tire circumferential direction. It is.

  According to <1>, since the number of blocks in the center block row is smaller than the number of blocks in the second block row adjacent to both sides, the tread rigidity in the center portion in the tread width direction is increased, and as a result, a slight steering during straight running is achieved. Steering stability can be sacrificed by increasing the number of blocks in the second block row that is not dominant with respect to the small steering angle to 1.5 to 2 times the center block row. Therefore, it is possible to ensure the traction performance necessary for running on ice and snow.

Also, according to <1> , the number of blocks in the third block row, which plays a dominant role in steering stability with respect to a large steering angle, has been reduced to the same number as the center block row. Steering stability at the time can be ensured.

<2> According to <2> , since a part of the tire circumferential direction side end of the blocks constituting the center block row protrudes in the tire circumferential direction, the rigidity of the center block row is further increased and the straight running stability is improved. Can be made.

According to <3> , since the pin sipe that does not open to any groove portion is disposed in the portion of the block constituting the center block row that protrudes in the tire circumferential direction, it is adjacent to the protruding portion in the tire circumferential direction. It can be prevented by the water absorption action of the pin sipe that the groove between the blocks is narrowed and the drainage performance is lowered.

A studless tire according to an embodiment of the present invention will be described below with reference to the drawings. Figure 2 is a developed view of a tread of the studless tire, the tread surface 10, the block row formed by arranging blocks in the circumferential direction have ordered odd number, in the illustrated, extending in the tire circumferential direction A center block located in the center in the order of arrangement in the tire width direction, in which five block rows 2A, 2B, 2C, 2D, and 2E partitioned by four circumferential grooves 1A, 1B, 1C, and 1D are arranged. The row 2A is configured by arranging a number of blocks 4A adjacent to each other across the lateral groove 3A in the circumferential direction, and the second adjacent to both sides in the width direction of the center block row 2A across the circumferential grooves 1B and 1C. The block rows 2B and 2C are also configured by arranging a large number of blocks 4B and 4C adjacent to each other across the lateral grooves 3B and 3C in the circumferential direction. Similarly, the second block rows 2B and 2C are arranged . Third block rows 2D and 2E located on the outer side in the tire width direction of C are also configured to include a large number of lateral grooves 3D and 3E and blocks 4D and 4E.

In the present invention, as a feature thereof, when the total number of blocks 4A in the center block row 2A is n, the number of blocks in the second block rows 2B and 2C is 1.5n to 2.0n. In the case shown in FIG. second block rows 2 B that are adjacent to the other widthwise side of the center block row 2A has 2.0n blocks, the second block row 2 C is 1.5n number of adjacent one widthwise side of the center block row 2A By controlling the number of blocks in the center block row 2A to be 1 / 1.5 or less of the second block row 2C , it plays a dominant role in responsiveness and stability to a small steering angle during straight running As a result, the straightness of the center block row 2A is increased and the center block row 2A is reduced as a trade-off. The traction performance can be ensured by increasing the number of blocks in the second block arrays 2B and 2C, which are not dominant for straight running stability.

  In the tire of the present invention, it is preferable that the number of blocks in the third block rows 2D and 2E is the same as that in the center block row 2A. By maintaining the rigidity of the third block rows 2D and 2E at the center of the tire, Responsiveness and stability at a large steering angle at the time can be ensured as in the conventional case.

  More preferably, at least the block 4A of the center block row 2A has a projecting portion 6 formed by projecting a part of the end 5 on the tire circumferential direction side in the tire circumferential direction. The tread rigidity of the row 2A can be further increased, and the straight running stability can be further improved. In this case, preferably, the protruding portion 6 makes a part of the lateral groove 3A narrow and the drainage performance is reduced. A pin sipe 7 that does not open to any groove is formed in the portion 6.

Since the pin sipe 7 is not a sipe that opens into a groove portion that is normally employed, the rigidity of the protruding portion 6 is hardly reduced. Incidentally, the blocks 4A, 4B, 4C, 4D, 4 E, the portion other than the protruding portion 6, the sipe open to the groove, are large number formed in accordance with the rigidity and the drainage performance required.

  A number of tires in which the number of blocks in the center block row is fixed, and the number of blocks in the other block row is changed in comparison with the number of blocks, and these are designated as Examples 1-3, Comparative Examples 1-3, and For these examples, the snow feeling test, snow brake test, snow traction test, ice feeling test, ice brake test, straight running stability feeling test, and steering stability feeling test were conducted on these examples. The results are shown in Table 1. Table 1 also shows the ratio P1 of the number of blocks in one second block sequence, the ratio P2 of the number of blocks in the other second block sequence, and the ratio P3 of the number of blocks in the third block sequence (same on the left and right) with respect to the center block sequence. Indicated.

The common specifications of the prototype tires are as follows.
Tire size: 195 / 65R15
Number of blocks in center block row: 56

  The various tests were carried out by mounting these tires on a predetermined rim and filling them with a predetermined air pressure, and then mounting them on an actual vehicle.

  In the above description, the predetermined internal pressure and the predetermined rim are defined as follows. That is, the predetermined internal pressure is the air pressure corresponding to the predetermined load in the application size described in the predetermined industry standard, and the predetermined rim is the standard rim (or “Approved” in the application size described in the standard. Rim ”,“ Recommended Rim ”). In addition, the predetermined load in the above is the maximum load (maximum load capacity) of the single wheel in the application size described in the predetermined industrial standard.

  For such industrial standards, there are standards that are valid in each region where tires are produced or used. For example, in the United States, “The Tire and Rim Association Inc. Year Book” (including design guides) ) In Europe according to “The European Tire and Rim Technical Organization Standards Manual” and in Japan according to “JATMA YEAR BOOK” of the Japan Automobile Tire Association.

  In the snow feeling test, the driver comprehensively evaluates the braking performance, starting performance, straight running performance, and cornering performance on the test course of the snowy road surface, and the index when the evaluation result of the conventional tire is set to 100 is shown in Table 1. Indicated.

  In the snow traction test, the acceleration time from the start on the snowy road surface until reaching a distance of 50 m was measured, and the index when the measurement result of the tire of the conventional example was set to 100 is shown in Table 1.

  In the straight running stability feeling test, the driver comprehensively evaluates the responsiveness and stability when steering at a slight angle when driving straight on a dry road test course. The index is shown in Table 1.

The steering stability feeling test is an index when the driver comprehensively evaluates the responsiveness and stability when steering on a dry road test course and the conventional tire evaluation result is 100. Table 1 shows.

  As is clear from Table 1, the performance of the example can improve the performance on snow without sacrificing the straight running stability or the steering stability compared to the conventional example and the comparative example.

It is an expanded view which shows the tread surface of the conventional studless tire. It is an expanded view which shows the tread surface of the studless tire which concerns on this invention.

Explanation of symbols

1A, 1B, 1C, 1D Circumferential groove 2A, 2B, 2C, 2D, 2E Block row 3A, 3B, 3C, 3D, 3E Lateral groove 4A, 4B, 4C, 4D, 4E Block 5 End of the tire circumferential side 6 blocks 7 Pinsipe 10 Tread

Claims (3)

In a studless tire with an odd number of block rows arranged in the circumferential direction on the tread surface, arranged in the width direction,
Among these block strings, when the block string located in the center in the arrangement order is called a center block string and the block strings located on both outer sides of the center block string are called second block strings, the second block with respect to the center block string The column has 1.5 to 2 times the number of blocks ,
A studless tire characterized in that when the block rows located on both outer sides of the second block row are called third block rows, the third block row and the center block row have the same number of blocks . The studless tire according to claim 1 , wherein a part of the tire circumferential direction side end of the block constituting the center block row protrudes in the tire circumferential direction. 3. The studless tire according to claim 2 , wherein a pin sipe that does not communicate with any groove portion is disposed at a portion of the block constituting the center block row that protrudes in the tire circumferential direction.

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