JPH06143935A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire used for both off-road (including dirt road) and on-road. CONSTITUTION:This pneumatic tire is provided with a tread 1 having the tread width divided by the tread circumferences into three parts to provide the central region 2 and both side regions 3 between both edges and a pair of circumferential main grooves 4 near boundaries between these regions. Further, the pneumatic tire is provided with a plurality of S-shaped cross grooves 6 crossing the circumferential main grooves 4 and extending between both tread edges 5 at interval along the tread circumference ad slant grooves 7 inclined in the opposite direction to the cross groove to cross a plurality of the cross grooves 6. The tread is formed with block-like land part 8 divided by these groove. The edges of the circumferential main grooves 4 have a gap therebetween narrower than those of the adjacent cross grooves 6 are arranged in a sea- through form staggered widthwise of the tread over the whole circumference of the tire, and both ends of the slant groove 7 are arranged to be stopped in the lands 8.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Excellent driving performance on off-roads (including dirt roads) in fields, mountains, rivers, deserts, etc., as well as drainage and braking on general roads, especially on wet roads. In regards to pneumatic tires that have excellent high-speed stability and noise characteristics on dry road surfaces, we are proposing to improve the tread pattern of all-wheel drive (four-wheel drive), which is suitable for use in passenger cars and light trucks. is there.

[0002]

2. Description of the Related Art Off-road tires have a tread with as many edges as possible in order to obtain steering stability such as driving / braking performance and cornering on an unpaved road. That is, it is common to employ a tread pattern that can sufficiently exhibit the edge effect. Further, since the tread pattern of this off-road tire is formed mainly for the purpose of exerting the edge effect, it is also useful when used on a snowy road.

As the above-mentioned tire, a tread,
There is a block pattern tire that is provided with a plurality of straight and zigzag circumferential grooves, lateral grooves intersecting with these circumferential grooves, and a plurality of sipes on the land portion of the tread sectioned by these grooves (Fig. 3).

[0004]

As the performance of four-wheel drive passenger cars and light trucks has improved, even for pneumatic tires used therefor, both on-road and off-road depending on usage conditions. The versatility of being usable may be required.

However, tread patterns of tires suitable for running on these road surfaces are different from each other. That is, in on-road driving, from the viewpoint of straight running stability at high speed running and hydroplaning resistance on wet road surface, it is desirable that the circumferential groove has a shape that extends straight over the entire circumference of the tread, and the transverse groove has drainage property. It is desirable that the point has a continuous shape in the tread width direction. On the other hand, in off-road traveling, it is desired that the circumferential groove and the lateral groove have a zigzag shape as described above. Therefore, the proper groove shapes of both are in a contradictory relationship, and therefore, the pneumatic tire having the current tread pattern cannot satisfy both on-road and off-road required performances.

Therefore, the object of the present invention is not only excellent running performance on off-road but also excellent performance on on-road, especially drainage and braking performance on wet road surface, high-speed stability and noise performance on dry road surface. And improved on-road
It is to provide a pneumatic tire for both off-road use.

[0007]

According to the present invention, a tread is divided into a central region and both side regions by a tread circumference that divides the tread width into four equal parts from both ends thereof, and a pair of circumferences is provided near these boundaries. A plurality of S-shaped transverse grooves which are provided with main grooves and further extend between the tread ends across the circumferential main grooves at intervals along the tread circumference; A slanted groove that intersects with a book is provided, and a block-shaped land portion that is divided by these grooves is formed on the tread, and the groove edge of the circumferential main groove is spaced at an interval narrower than that of the adjacent transverse grooves. Is a staggered see-through arrangement that is alternately displaced in the tread width direction over the entire circumference of the tire, and both ends of the inclined groove are end stop arrangements that are located on land portions. Also, the transverse groove intersects at a step that should occur on the groove edge of the circumferential main groove,
It is more preferable that the transverse grooves have a discontinuous arrangement in which the circumferential main grooves are divided by inclined grooves, and that each land portion has a plurality of sipes along the transverse grooves.

An example of a pneumatic tire according to the present invention is shown in FIG.
In the figure, 1 is a tread, 2 is a central region, 3 is a lateral region, 4 is a circumferential main groove, 5 is a tread end, 6 is a transverse groove, 7 is an inclined groove, and 8 is a block-shaped land portion. Is.

In the pneumatic tire of the present invention, the tread 1 is divided into a central region 2 and both side regions 3 by a tread circumference which divides the tread width into four equal parts from both ends thereof, and a pair of circles are provided near these boundaries. A circumferential main groove 4 is provided, and the groove edges of the circumferential main groove are arranged in a staggered see-through arrangement in which they are alternately displaced in the tread width direction over the entire circumference of the tire. The see-through arrangement means that the inside of the circumferential main groove can be seen along the circumference of the tread.

Further, the pneumatic tire of the present invention has a plurality of S-shaped transverse grooves 6 extending between both tread ends 5 across these circumferential main grooves 4 at intervals along the circumference of the tread, and the transverse grooves. An inclined groove 7 that is inclined in the opposite direction and intersects with a plurality of them is provided, and a block-shaped land portion 8 is formed by being divided by these grooves, and both ends of the inclined groove 7 are land portions 8. It has an end stop arrangement located at.

The transverse groove 6 is preferably arranged at an angle of 30 to 50 ° with respect to the plane including the tread circumference in the central region 2 and 70 to 90 ° with respect to the plane in the lateral region 3.
If the arrangement angle in the central region 2 is less than 30 °, the cornering property is improved, but especially the driving / braking performance on a dirt road cannot be obtained sufficiently, and if it exceeds 50 °, the opposite phenomenon occurs. Further, the arrangement angle in the lateral region 3 is set to 70 to 90 ° because the drainage property in the tread width direction and the block rigidity are ensured and the driving on the dirt road is performed.
This is to maintain the braking performance, and to prevent the noise profile from being deteriorated by matching the ground contact shape and the transverse groove shape at the time of left and right cornering.

Further, it is preferable that the transverse groove 6 intersects with the groove edge of the circumferential main groove 4 at a step which should occur, from the viewpoint of ensuring a longer and continuous edge component in the circumferential direction. When the drainage property is important, the arrangement shape of is preferably a continuous S-shaped curve, and when the edge effect is important, the inclined grooves 7 are provided between the circumferential main grooves 4 as shown in FIG. It is preferable to make it discontinuous by dividing by.

The inclined groove 7 is inclined in the opposite direction to the transverse groove 6 and intersects a plurality of them, so that the inclined groove 7 is formed.
A zigzag-shaped groove extending substantially in the circumferential direction is formed in the central region 2 by connecting the cross groove 6 with the cross groove 6. By arranging the zigzag-shaped groove in the central region 2 where the contact surface pressure is high and the running performance of the tire is largely controlled, the edge component of the land portion 8 is increased, so that the steering stability on the dirt road is improved. In order to form more of this zigzag-shaped groove in the central region 2, it is preferable that the inclined groove 7 intersects with at least four or more transverse grooves 6, and the inclined groove 7 includes each transverse groove 6.
On the other hand, it is preferable that at least two intersect.

Further, the cut length of the inclined groove 7 is preferably longer in the circumferential direction than the ground contact length. High at least drainage can be expected by removing at least one tip end side of the inclined groove 7 from the ground contact surface. The arrangement angle of the inclined groove is preferably 5 to 30 ° with respect to the plane including the circumference of the tread. If it is less than 5 °, drainage and noise are improved, but driving and braking performance is reduced. If the angle exceeds 30 °, the opposite tendency occurs. Therefore, in order to balance the performance maintenance of both, the arrangement angle in the above range becomes preferable. Also, the increase of land edge component,
In order to reduce noise, the inclined groove 7 may be a linear connecting groove that is bent as shown in FIG.

The reason why the both ends of the slanted groove are located at the land portion is to maintain the block rigidity while increasing the land edge component, which results in high steering stability on dirt roads. can get. Further, in order to increase the land edge component, it is preferable to have a plurality of sipes along the transverse groove in the land.

[0016]

The pneumatic tire of the present invention is provided with the circumferential main groove 4, the transverse groove 6, and the inclined groove 7 intersecting with the transverse groove 6 on the tread, and these are properly arranged. However, their actions are as follows.・ Operation by the main circumferential groove 1. Since the circumferential main groove has a shape that allows the inside of the groove to be seen along the circumference of the tread, high drainage can be obtained. 2. Providing grooves along the circumference of the tread provides high speed stability. 3. In addition to the high edge effect against the lateral force generated during cornering, the groove edges of the circumferential main groove are staggered in the tread width direction alternately over the entire circumference of the tire, so the edge component for the driving / braking force increases. The edge effect of is also obtained.

Operation by the transverse groove The arrangement angle of the transverse groove is set to the plane including the tread circumference.
By making it smaller in the central area and larger in both sides,
The edge effect is secured for both driving / braking force and lateral force in the central region, and lateral drainage and land rigidity can be maintained in the lateral region, and the ground contact shape and this groove shape during cornering can be maintained. Since they do not match, they also have excellent noise characteristics.

Operation by inclined groove 1. By inclining the inclined groove at an acute angle with respect to the plane including the tread circumference, excellent drainage and cornering properties can be obtained. 2. By intersecting the inclined groove with a plurality of transverse grooves, a zigzag groove is formed substantially in the circumferential direction in the central region,
Improves cornering ability and driving / braking ability against lateral force. 3. By providing both ends of the slant groove with end stop arrangements located on the land portion, the land edge component can be increased without lowering the land portion rigidity.

[0019]

Example A pneumatic tire having a tire size of 31 × 10.50R15 and a tread width of 208 mm was used as a test tire. The structure other than the tread has a known structure.

◎ Test tire Fig. 1 shows an example of a typical tread pattern of the tire of the present invention.
2 and FIG. 4 show a conventional tire. -Example 1 In the invention tire having the tread pattern shown in FIG. 1, the groove edges of the circumferential main grooves are alternately displaced in the tread width direction over the entire circumference of the tire at intervals smaller than the intervals of the transverse grooves adjacent to each other. It has a staggered see-through arrangement. The groove width of the circumferential main groove is 14 mm, the groove length is 30 mm between the steps of the groove edge of the circumferential main groove, and the deviation of the groove edge is 3.5 mm. The transverse groove of the S-shaped curve has an arrangement angle of 75 ° in the lateral region and 40 ° in the central region with respect to the plane including the tread circumference.
The groove width was 10 mm in the lateral area and 5 mm in the central area. The inclination groove has an arrangement angle of 17 ° with respect to the plane and a groove width of 10 mm. Three sipes were arranged along the transverse groove in the land portion defined by the transverse groove. Further, from the vicinity of the tread end 5 to the outside, an enlarged groove having a wide groove width is provided for soil and snow removal.

Example 2 In the invention tire having the tread pattern shown in FIG. 2, the groove edges of the circumferential main grooves are arranged in the tread width direction over the entire circumference of the tire at intervals smaller than the intervals of the transverse grooves adjacent to each other. It has a staggered see-through arrangement that alternates. The groove width of this circumferential main groove is 14 mm, the groove length is 30 mm at the step of the groove edge of the circumferential main groove, and the deviation of this groove edge is 3.5 mm. The transverse groove of the S-shaped curve has an arrangement angle of 75 ° in the lateral region and 50 ° in the central region with respect to the plane including the tread circumference, and the groove width is 10 mm in the lateral region and in the central region, The central portion was 5 mm, and the outer portion was 8 mm. The slanted groove consists of a combination of three linear grooves having two inflection points, intersecting five transverse grooves and two for each transverse groove. In this inclined groove, the two straight grooves including the respective cut ends are arranged at an angle of 12 ° and 16 ° on both side walls with respect to the plane, and the groove width is 12 mm on the cut end side and the opposite side. Was 19 mm, and the arrangement angle of the remaining linear groove was 29 ° with respect to the plane and the groove width was 8.5 mm.
Further, three sipes are arranged along each of the transverse grooves in the land portion defined by the transverse grooves, and the tread end 5
An enlarged groove with a wide groove width is provided from the vicinity to the outside for soil and snow removal.

Conventional Example A tire having the same structure as the invention tire shown in Example 1 except that it has the tread pattern shown in FIG.

◎ Test method The test was carried out under the conditions of regular tire internal pressure and regular load (corresponding to two actual vehicles) according to JIS. The tests were conducted on dirt running performance, snow performance, drainage and braking performance on wet road surface, high-speed stability and noise performance on dry road surface. The dirt runnability test is a feeling evaluation when running at a speed of 40 to 80 km / h on a hard dirt test course in which fine gravel is scattered in the geology of volcanic ash. Test course speed 20-6
It is a feeling evaluation when traveling at 0 km / h,
The drainage performance on a wet road surface is evaluated by the limit speed at which a hydroplaning phenomenon occurs when running on a road surface with a water depth of 5 mm, and the braking performance on a wet road surface is evaluated by measuring the friction force during braking. However, the high-speed stability is a feeling evaluation when traveling on a test course on a dry road surface at a speed of 60 to 120 km / h, and the noise property is a feeling evaluation when traveling on a test pattern noise road at a speed of 40 to 80 km / h. The pattern noise was measured and evaluated.

◎ Test results Table 1 shows the results of the above tests. In addition, the numerical values in the table are represented by index comparison with the conventional example as 100 in all tests, and the larger the value, the better the performance.

[0025]

[Table 1]

From these test results, the tire of the present invention is excellent in drainage and braking performance on wet road surface, high-speed stability and noise performance on dry road surface while maintaining the performance on dirt road and ice and snow road surface. I understand.

[0027]

According to the present invention, the tread has a circumferential main groove,
By arranging transverse grooves and inclined grooves appropriately, not only does it have excellent running performance on off-roads in fields, mountains, rivers, deserts, etc., but also on-road drainage and braking on wet road surfaces. On dry roads, it can exhibit high-speed stability and excellent noise performance. Therefore, it is possible to provide a pneumatic tire that can be used for both off-road and on-road use, and in particular, it can be applied to a four-wheel drive passenger car and a light truck.

[Brief description of drawings]

FIG. 1 is a representative invented tire used in Example 1, and is an overall view of a main portion of a developed tread portion of the tire.

FIG. 2 is another invention tire used in Example 2, and is a front view of the main part of the developed tread part.

FIG. 3 is a front view of a main part of a conventional tire having a zigzag-shaped circumferential main groove and a transverse groove, the tread portion of which is developed.

FIG. 4 is a front view of another main part of another conventional tire having a zigzag-shaped circumferential main groove and a transverse groove used in a conventional example, in which a tread portion is developed.

[Explanation of symbols]

 1 Tread 2 Central area 3 Side area 4 Circumferential main groove 5 Tread edge 6 Transverse groove 7 Inclined groove 8 Land portion 9 Circumferential groove 10 Lateral groove 11 Sipe

Claims (4)

[Claims] 1. The tread is divided into a central region and both side regions by a tread circumference that divides the tread width into four equal parts from both ends thereof, and a pair of circumferential main grooves is provided near these boundaries, and the tread circle is further provided. A plurality of S-shaped crossing grooves that extend between both tread ends crossing these circumferential main grooves at intervals along the circumference, and tilt grooves that incline in the opposite direction to these crossing grooves and intersect with these plural grooves are provided. The tread width of the circumferential main groove is formed over the entire circumference of the tire by forming a block-shaped land portion on the tread, which is divided by these grooves, at intervals smaller than the intervals of the transverse grooves adjacent to each other. A pneumatic tire characterized by a staggered see-through arrangement that is staggered in alternating directions, with both ends of the inclined groove being an end stop arrangement located on the land. 2. The pneumatic tire according to claim 1, wherein the transverse groove intersects with a groove edge of the circumferential main groove at a step that should occur. 3. The pneumatic tire according to claim 1, wherein the transverse grooves have a discontinuous array in which the circumferential main grooves are divided by inclined grooves. 4. The pneumatic tire according to claim 1, wherein each land portion has a plurality of sipes along the transverse groove.