JPH064366B2 - Pneumatic tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pneumatic tire that can be suitably used for traveling on a paved road surface and an uneven terrain together.

[Conventional technology]

Tires mounted on all-terrain vehicles used on sand, mud, uneven road surface or uneven terrain with rocks are kept at a relatively low internal pressure in order to mitigate the impact of obstacles on the road surface during running. In addition, the tread portion has a block pattern and the tread portion is made flexible by reducing the land / sea ratio.

[Problems to be Solved by the Invention] However, when a tire having a conventional tread pattern is traveling on a paved road surface instead of on the rough terrain, deformation of the tread rubber during grounding, compression and release of air inside the tread Noise caused by the above is likely to occur.

On the other hand, noise level 75d due to noise regulation in 1985
Must be suppressed below B.

In addition, the use of all-terrain vehicles has been greatly improved in their motor functions with the expansion of their applications. Especially, vehicles equipped with suspension are emerging, and the engine displacement is 50
It has been used for driving on paved roads with high output of 00cc or more and high speed of 180km / h. As a result, even in a tire having a block pattern, in order to enable high speed running, it is desired that the block retains sufficient strength and rigidity, and that crack damage that tends to occur particularly in the block at the center of the tread is prevented. .

An object of the present invention is to provide a pneumatic tire capable of running on rough terrain such as sand and mud and running on a pavement and reducing noise.

[Means for Solving the Problems]

The present invention relates to a central block row consisting of central blocks arranged at intervals in the tire circumferential direction along the tire equator, an outer block row consisting of outer blocks arranged in the tire circumferential direction along the tread edge, and the central block. In a pneumatic tire having a block pattern in which a middle block row composed of inner blocks arranged in the tire circumferential direction between the row and the outer block row is provided in the tire tread portion, the width in the tire axial direction is the tread width. 5 to 15% and a height smaller than that of the central block, and by providing a connecting portion that connects the central blocks in the tire circumferential direction through the tire equator, only the central block row is continuous in the tire circumferential direction. In addition, the outer block and the inner block are polygonal blocks having at least five corners. It is a pneumatic tire that does.

[Action]

In this way, by using the central rib that connects the central block row that passes through the tire braking surface, which is effective for improving grip on rough terrain, at the connecting portion, the strength and rigidity of the central block row can be increased and the pavement can be improved. The road surface can be prevented from being damaged while traveling and noise can be reduced, and the small height of the connecting part enhances grip and maintains the road performance on uneven terrain. Grip property can be improved by making it more than one.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 shows that the pneumatic tire has tire size 460-1.
Taking the case of 8.4 PR as an example, the tread pattern of the tread surface is shown.

In the tread portion T of the pneumatic tire, a central rib R that passes through the tire equator and is continuous in the tire circumferential direction is arranged in the central portion. Further, the central rib R is arranged at regular intervals in the tire circumferential direction. A central block row 1 composed of central blocks 2 ... 3 ... and a rib shape in which only the central block row 1 is continuous in the tire circumferential direction by connecting the central blocks 2 ... And the connecting portion 4 serving as the central rib R. In the tire of the present invention,
The connecting portions 4 ... Are provided only in the central block example 1.

Further, the central block 2 has a polygonal shape having 10 corners formed by intersecting two upside-down trapezoids, which are arranged in the tire axial direction and one of which passes through the tire equator, on their long parallel sides. The block 3 is line-symmetric with respect to the block 2 with respect to the tire equator.

Further, the connecting portions 4 are belt-shaped bodies whose both sides extend in the tire circumferential direction, and connect the central blocks 2, ..., 3 through the tire equator.

Also, the height from the groove bottom of the central blocks 2 and 3 is usually 6 to 12% of the tread width TW, as can be easily determined by those skilled in the art.
It is set to a level that improves grip on rough terrain.

On the other hand, the connecting portion 4 is smaller in height than the central blocks 2 and 3, for example, 40 to 85 which is the height of the central block.
By setting the height to be about%, it is possible to provide gripping property, thereby maintaining the traveling property on the rough terrain road surface. Further, the connecting portions 4 pass through the tire equator and the central block 2
By making only the central ribs R continuous in the circumferential direction of the connection shite tire, the rigidity of the central block row 1 along the tire equator of the tire tread portion is increased, and crack damage in the central block row that tends to occur during pavement road running By preventing this, increasing the rigidity of the tread portion, and suppressing the vibration of the block, it is possible to reduce the noise.

The width W of the connecting portion 4 in the axial direction of the tire is in the range of 5 to 15% of the tread width TW. If the width W is less than 5%, the rigidity of the block crack in the central portion of the tread cannot be sufficiently maintained, and noise can be sufficiently suppressed. Not only that, crack damage due to high-speed running is more likely to occur, and if it exceeds 15%, braking and driving force in rough terrain running will be reduced.

Further, the width W of the connecting portion 4 is the width B of the central blocks 2 and 3.
It is preferable to form 95% or less, preferably 70% or less of W and keep the basic tone of the block pattern as it is in the central portion of the tread. The width W is 20% or more of the width BW of the central block row 1 from FIGS. 1 and 2.

Further, as the central blocks 2 and 3, those having the same symmetrical shape are used in the present embodiment, but those having different shapes may be used together, and the central block has 7 to 10 corners. Is preferably adopted.

Further, in the tread portion T, outer blocks 6 and 7 are alternately arranged along the tread edge in the outer circumferential row 1 in the tire circumferential direction.
1, and an intermediate block row 12 composed of an inner block 9 arranged in the tire circumferential direction between the outer block row 11 and the central rib R.

The inner block 9 is composed of a polygonal block having seven corners in which a triangular portion is projectingly provided on a base of a substantially parallelogram having side parallel to the tire axial direction.

The outer block 6 has a mountain shape with five corners whose bottoms are aligned with the tread edge.

Further, the outer block 7 is a polygonal block having its bottom located at the tread edge and having slightly bent eight corners.

Further, the reason why the blocks 6, 7 and 9 are blocks having five or more corners together with the central block is that the braking performance and drivability on the rough road surface are taken into consideration, and the central blocks 2, 3, The blocks 6, 7, and 9 are all partitioned by grooves having substantially the same width.

In addition, the corners have braking performance and drivability on uneven terrain,
As shown in FIG. 1, only the corners at both ends of the side exceeding 5% of the entire circumference of the block are included. Further, since the outer block row 11 and the intermediate block row 12 are not provided with the connecting portions as described above, the number of the corner portions of each block is 5 or more, which enhances the grip performance and improves the The braking drivability on the ground level road surface can be maintained.

Further, the surface area on the tread surface of the central blocks 2, 3 and blocks 6, 7, 9 is determined by the land / sea ratio, and in this embodiment, the land / sea ratio is in the range of 35-55%. Here, the sea / land ratio means the central rib R and the bronque 6 which directly contact the ground in the region of the tire tread width TW,
The surface of 7 and 9 was defined as land, the rest or groove was defined as the sea, and the total area of the land within the area of the ground contact portion over the entire circumference of the tire was divided by the total area of the sea. The value is expressed as a percentage.

If the land / sea ratio is less than 35%, the noise level will not be sufficiently reduced and the abrasion resistance will be poor, and problems such as block breakage and damage will occur. On the other hand, if it exceeds 55%, braking performance, drivability, and noise performance on an uneven road surface are deteriorated, which is not preferable.

(Specific Example) In order to confirm the effect of the present invention, tire size 460-1
At 8.4 PR, the tread pattern was as shown in FIG. 1, and a prototype was produced according to the specifications in Table 1, and a noise test and a durability test were conducted. Similarly, as a comparative example, as shown in FIG. 2, a tread pattern having the shape shown in FIG.

(1) Noise test The prototype test was installed on a GPZ75D machine, and the noise level at a position 7.5 m away from the vehicle during elliptical traveling was measured while changing the traveling speed, and the results are shown in FIG. Shown as a graph. The noise level increases with speed,
It is noted that the embodiments of the present invention have a significantly reduced noise level. In addition, the noise level of accelerated running noise of 1985 is 75 dB (A), but this is intended for machines. If this is made to correspond to the noise level of elliptical passage, 65 dB (A) is the speed. Although it is the target value at 60 km / h, the noise level at the speed of 60 km / h was 62 dB (A) in the present invention.

(2) Durability test The prototype tire was mounted on a GPZ75D machine and JA
On the test course of the R1 circuit, the running speed was stepped up at 100 km / h and the state of cracks in the central rib after each 10 laps was checked. In Comparative Example, 150 km / h, 6 cracks were generated at the 5th lap, whereas in Example, 17 cracks were generated.
No cracks were observed at 0 km / h and 10 laps.

〔The invention's effect〕

As described above, the pneumatic radial tire of the present invention can travel on rough terrain and paved road surfaces without causing crack damage and can reduce noise.

[Brief description of drawings]

FIG. 1 is a partial front view of a tread portion of a tire of the present invention, FIG. 2 is a partial front view of a tread portion of a comparative example, and FIG. 3 is a graph showing the relationship between noise level and running speed. 1 ... Central block row, 2, 3 ... Central block, 4 ... Connection part, 6, 7 ... Outer block, 9 ... Inner block, 11 ... Side block row, 12 ... Intermediate block row, R ... Central rib.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-116508 (JP, A) JP-A-57-121903 (JP, A) Practical application Sho-57-185605 (JP, U) JP-A-60- 169305 (JP, A) JP 57-9968 (JP, B2) JP 58-24282 (JP, B2) JP 31-10801 (JP, Y1)

Claims (1)

[Claims] 1. A central block row consisting of central blocks arranged at intervals in the tire circumferential direction along the tire equator, an outer block row consisting of outer blocks lined up in the tire circumferential direction along the tread edge, and the central portion. In a pneumatic tire having a block pattern in which an intermediate block row composed of inner blocks arranged in the tire circumferential direction between the block row and the outer block row is provided in a tire tread portion, the width in the tire axial direction is a tread width. 5 to 15% of the height of the central block is smaller than that of the central block, and a connecting portion that passes through the tire equator and connects the central blocks in the tire circumferential direction is provided to continuously connect only the central block row in the tire circumferential direction. The outer block and the inner block are polygonal blocks having at least five corners. Pneumatic tire characterized by.