JPH0234408A - Structure of tire tread - Google Patents

Abstract

PURPOSE:To enhance the tracting performance especially in muddy place by giving a specific relationship between the front and rear edge position in the rotating direction and the length along the axis to a fore and an aft block forming the tread structure of a tire. CONSTITUTION:Groups 23, 24 of fore and aft blocks are provided in the tread part 22 of a tire 21 and arranged alternately in the circumferential direction a distance L apart from each other. Each block 23, 24 consists of fore and aft blocks 25, 27 a distance M apart from each other in the axial direction of the tire 21 in linear symmetricity about the equator 26 of the tire. The front edges 28, 29 of the blocks 25, 27 are extended in parallel with the axis of tire 21. The axial direction length A of rear edges 30, 31 shall alike be made shorter than the axial direction length B of the front edges 28, 29. The front edges 28, 29 are arranged between the fore and aft edges 28, 29, 30, 31 of blocks 25, 27 situated immediately before.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tire tread structure composed of a large number of blocks.

[Katsuyoshi Suetachi] As a conventional tire tread structure, the one shown in FIG. 5, for example, is known. This device is constructed by alternately arranging a front block group 1 and a rear block group 2 provided at the rear of the front block group 1 in the rotational direction of the tire 3 at equal distances from each other in the circumferential direction of the tire 3. There is a horizontal groove 4 between the front block group 1 and the rear block group 2.
is formed. The front block group 1 consists of a plurality of rectangular front blocks 5 arranged in the axial direction of the tire 3. Each front block 5 is spaced from each other by an equal distance, and there is a circumference between adjacent front blocks 5 that communicates with the lateral groove 4. A directional groove 6 is formed.

On the other hand, the rear block group 2 also consists of a plurality of rear blocks 7 arranged in the axial direction of the tire 3 and having the same shape as the front block 5. Each rear block 7 is spaced from each other by an equal distance, and adjacent rear blocks A circumferential groove 8 communicating with the lateral groove 4 is formed between the grooves 7 and 7. These rear blocks 7 are located at the center in the axial direction of the two front blocks 5 located immediately before and after the rotation direction.
That is, it is disposed axially shifted by 1/2 pitch with respect to the front block 5.

However, such a tire tread structure has a problem in that traction performance on muddy and itchy ground is low, and driving force may be insufficient when starting off. The reason for this is that the traction performance on the muddy PFI ground as described above is improved by the rotational direction leading edge 9 of the front and rear blocks 5 and 7, which are arranged within a unit area and function as edges.
10, that is, the axial length of the edge on the stepping side (axial component)
This is because the longer the total length, the higher the value, but in the tread structure as described above, the total length is not so long.

In order to solve such problems, front and rear blocks 5
, 7 are shortened in the circumferential direction to increase the total number of front and rear blocks 5.7 disposed within a unit area, thereby increasing the total axial length of the front edges of the blocks in the rotational direction. However, in this case, there is a problem that the bending rigidity of the front and rear blocks 5, 7 against the circumferential force becomes small, and the desired performance etc. also deteriorates.

An object of the present invention is to provide a tire tread structure with good traction performance on muddy ground.

The purpose of this is to extend the rotational leading edges of the front and rear blocks approximately parallel to the axis of the tire, and to make the axial length of the rotational trailing edges of the front and rear blocks equal to the rotational leading edge. After making the length shorter than the length in the axial direction and positioning the front edges of the front and rear blocks in the rotational direction immediately in front of these blocks in the rotational direction,
This can be achieved by positioning the front block between the front edge in the rotational direction and the rear edge in the rotational direction.

Here, it is preferable that the side walls at the front edges of the front and rear blocks in the rotational direction are inclined so as to move toward the front in the rotational direction as they move away from the axis of the tire.

1" First, in this invention, since the front edges of the front and rear blocks in the rotational direction extend approximately parallel to the tire axis,
The axial length of the leading edge in the rotational direction of each block is longer than that in the case where the leading edge in the rotational direction is inclined in a direction perpendicular to the axis of the tire, thereby making it possible to increase the aforementioned total length. In addition, in this invention, since the axial length of the rear edges in the rotational direction of the front and rear blocks is shorter than the axial length of the front edges in the rotational direction, there is a gap between two adjacent front blocks and between the rear blocks. A groove (space) in which no block exists is formed, which expands toward the rear in the rotational direction. For this reason, after being positioned immediately after the front and rear blocks in the rotational direction, the front block is translated forward in the rotational direction and a part of it enters the groove, and the front and rear blocks thus moved are The front edge in the rotational direction of the front block was positioned immediately in front of the moved blocks in the rotational direction, and then positioned between the front edge in the rotational direction and the rear edge of the front block in the rotational direction. As a result, the total number of front and rear blocks arranged within a unit area can be increased without shortening the circumferential length of the front and rear blocks, that is, without reducing the circumferential rigidity. As a result, the total length in the axial direction of the front edges of the front and rear blocks in the rotational direction within a unit area becomes longer, thereby improving traction performance on muddy ground.

If the side walls at the front edges of the front and rear blocks in the rotational direction are inclined as described above, the front edges of each block in the rotational direction will have sharp edges, which will make it easier to bite into the road surface. This further improves traction performance, etc.

Practical Example Hereinafter, a first example of the present invention will be described based on the drawings.

In FIG. 1, 21 is a pneumatic tire, and a front block group 23 and a rear block group 24 provided at the rear of the front block group 23 in the rotational direction are arranged on the tread portion 22 of this tire 21. The front block group 23 and the rear block group 24 are arranged alternately in the circumferential direction at equal distances from each other.

Each front block group 23 is composed of a plurality of front blocks 25, and these front blocks 25 are spaced apart from each other by an equal distance M in the axial direction of the tire 21, and arranged symmetrically with respect to the tire equatorial plane 28 as an axis of symmetry. There is.

On the other hand, each rear block group 24 also includes a plurality of rear blocks 27
These rear blocks 27 are composed of tires 21
are spaced apart from each other by an equal pressure @M in the axial direction, and are arranged line-symmetrically with the tire equatorial plane 2B as the axis of symmetry. The rear blocks 27 of these rear block groups 24 are axially separated by 1/1 of the contraction M with respect to the front blocks 25 of the front block group 23.
As a result, the rear block 27 is located between the two front blocks 25, which are placed immediately before and after the rotation direction. Further, the front block 25 and the rear block 27 are all of the same shape, and their front edges 28 and 29 in the rotational direction, that is, the edge on the stepping side that first contacts the road surface when moving forward, extend parallel to the axis of the tire 21. It has a straight line shape. Here, traction performance on muddy ground is generally arranged within a unit area. The longer the sum of the axial lengths of the front edges in the rotational direction of the blocks that function as edges, the higher the value becomes. Assuming that the total number of blocks arranged within this unit area is seven, the total value is the sum of seven axial lengths of the leading edges in the rotational direction of each block. As a result, if the rotational direction front edges 28.28 of the front block 25 and rear block 27 extend parallel to the axis of the tire 21 as described above, even if the block shapes are the same, the rotational direction front edges 28. .29 is inclined in a direction perpendicular to the axis of the tire 21, the total value becomes longer and the traxbon performance becomes better. In addition, the front block 25 and the rear block 2
The axial length A of the rear edges 30, 31 in the rotational direction of No. 7, that is, the edge on the kicking side that touches the road surface last during forward movement, is the front edge 28.31 of the front block 25, rear block 27 in the rotational direction.
29, substantially close to zero in this embodiment, and both axial ends of the rotational leading edges 28, 29 and the rotational trailing edges 30.29 of the front block 25, rear block 27. Two side edges 32 and 33 connecting the axial ends of the tire 31 are both linear and inclined at an angle C of about 45 degrees with respect to the tire equatorial plane 2B. As a result,
Each front block 25. Circumferential length D of rear block 27
That is, the thickness does not decrease, and the bending rigidity of the front block 25 and the rear block 27 against the circumferential force hardly decreases.
When the axial length A is shorter than the axial length B of the front edge 28, 29 in the rotational direction, the space between the two adjacent front blocks 25 and the rear block 27 gradually widens toward the rear in the rotational direction. Trapezoidal grooves 34 and 35 (spaces) are formed respectively, and naturally there are no blocks in these grooves 34 and 35. Therefore, in this embodiment, the front side blow.

The rear block 27 located immediately after the rotation direction of the rear block 25 and the front block 25 located immediately after the rotation direction of the rear block 27 are moved forward in the rotation direction, so that their front edges 23.28 in the rotation direction are aligned with the side edges 32.33. The rear block 27 and the front block 25 are moved in parallel until they come into contact with each other.
The front end in the direction of rotation of the groove 34, 35 is inserted into the groove 34,35. As a result, the front edges 29 and 28 of the rear block 27 and the front block 25 in the rotation direction that have been moved in parallel are the front edges 29 and 28 of the front block 25 and the rear block 27 that are located immediately in front of the rear block 27 and the front block 25 in the rotation direction. Rotation direction leading edge 2
8.29 and the rear edge 30.31 in the rotational direction, and the circumferential distance between the front block 25 and the rear block 27 is the same as that between the front block 5 and the rear block 7 of the prior art. It is much shorter than the circumferential distance. As a result, the total number of front blocks 25 and rear blocks 27 arranged within a unit area increases, and the number of front blocks 25 and rear blocks 27 arranged within a unit area increases.
5. The total length in the axial direction of the front edges 28, 28 in the rotational direction of the rear block 27 is increased, and the traction performance on muddy and itchy ground is improved. In addition, the sum of the axial lengths of the front edges 28 in the rotational direction of all the front blocks 25 included in the front block group 23 of one row is added to
The rear block group 24 of one column located immediately after the rotation direction of
When the sum of the axial lengths of all the rear blocks 27 included in the tread width W is added, this added value is
120% or more, and the circumferential pitch from any front block 25 to the front block 25 disposed immediately after the front block 25 in the rotational direction (in this example, the same as the circumferential length D of the front block 25) ) is the tread width W
The reason for this is that if it deviates from the above range, the total length in the axial direction of the leading edges in the rotational direction of all the blocks arranged within a unit area is originally too short, resulting in poor traction performance. etc. do not improve much. Further, as shown in FIG. 2, the side walls 41 at the front edges 28 and 29 in the rotational direction of each of the front block 25 and the rear block 27 are inclined toward the front in the rotational direction as they move away from the axis of the tire 21. As a result, each front block 25,
The front edges 28 and 29 of the rear block 27 in the rotational direction form sharp knees and jis, which makes it stronger to bite into the road surface when stepping on the pedal, further improving traction performance and the like.

Next, a test example will be explained. For this test, after preparing a comparison tire as shown in Figure 5 and a test tire as shown in Figure 1, these tires were mounted on a passenger car and the vehicle was driven uphill by 4 degrees. Starting tests were repeated on muddy and sandy roads. The number of times the test started successfully was counted, and the number of successes of the comparison tire (6 out of 10) was converted into an index of 100. When the test tire was rotated in the normal direction, the index was 140. The index was 75 when the test tire was rotated in the opposite direction to the normal direction. From this, it can be understood that the test tire rotated in the normal direction has better traction performance than the comparative tire. The size of the tires used in the above tests were both 175/70SR13.

FIG. 3 is a diagram showing a second embodiment of the invention. In this embodiment, the side ends 53 and 54 of the front block 51 and the rear block 52 are respectively step-shaped, so that the front parts of the front and rear blocks 51 and 52 in the rotational direction have the same wide width. On the other hand, the rear part in the rotational direction has the same narrow width, and has a T-shape as a whole. As a result, the grooves 55 between the front blocks 51 and the grooves 5B between the rear blocks 52 are connected to the front blocks 51,
The rear block 52 has an inverted T-shape in which the width rapidly increases at the center in the rotational direction. And the front block 5
1. The rear block 52 is translated forward in the rotational direction,
Only the wide rotational front portions penetrate into the respective grooves 56,55. At this time, the front block 51 and the rear block 52 are not in contact at any point, and a groove of approximately equal width is formed between them.

FIG. 4 is a diagram showing a third embodiment of the present invention. In this embodiment, the rotational front edges 63, 64 of the front block 61 and the rear block 62 are curved, that is,
The center part in the width direction is recessed toward the rear in the rotation direction, and
Front edge of rotation direction B3.64 of front and rear blocks 61.62
I&6 is located immediately before the front and rear blocks 81.62 in the rotation direction, and after the front blocks 82.61 in the rotation direction.
6.65, respectively.

1 As explained above, according to the present invention, traction performance on muddy ground, etc. can be improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a tread portion showing a first embodiment of the present invention, FIG. 2 is a sectional view taken along the line II in FIG. 1, and FIG. 3 is a tread portion showing a second embodiment of the present invention. FIG. 4 is a plan view of the tread portion showing the third embodiment of the present invention, and FIG.
The figure is a plan view showing a tread portion of a conventional tire. 21...Tire 23...Front block group 2
4... Rear block group 25.51.61... Front block 27.52.82... Rear block 2nd, 28.83.84... Front edge in rotational direction 30, 31
．． 85.8B... Rear edge in the rotational direction 41... Side wall A... Axial length of the rear edge in the rotational direction B... Axial length of the leading edge in the rotational direction

Claims (2)

[Claims] (1) A front block group consisting of a plurality of front blocks arranged apart from each other in the axial direction of the tire, and a plurality of rear blocks arranged at the rear of the front block group in the rotational direction and arranged apart from each other in the axial direction of the tire. Consisting of side blocks,
In a tire tread structure configured by alternately arranging a rear block group in the circumferential direction of the tire, each rear block is located between two front blocks, The edges extend substantially parallel to the axis of the tire, and the axial length of the rear edges in the rotation direction of the front and rear blocks is shorter than the axial length of the front edges in the rotation direction, and the front,
A tire tread structure characterized in that the front edge of the rear block in the rotation direction is located immediately before the rotation direction of these blocks, and then located between the front edge of the front block in the rotation direction and the rear edge of the front block in the rotation direction. (2) The tire tread structure according to claim 1, wherein the side walls at the front edges in the rotational direction of the front and rear blocks are inclined toward the front in the rotational direction as they move away from the axis of the tire.