JPH0392402A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve wet performance and abrasion resistance of a tire for cargo vehicle having a block row in the central zone by forming a cross groove by a narrow section whose groove walls are brought into contact with each other in the contact state with the ground under loaded rotation and a wide section, and by opening the narrow section in one of the circumferential groove and the wide section in the other circumferential groove. CONSTITUTION:A block row 7 is formed in the tire central zone 3 by a circumferential groove 2 and a cross groove 5. And this cross groove 5 is formed by a narrow section whose groove walls are brought into contact with each other in the contact state with the ground under loaded rotation of the tire and a wide section 9 whose groove walls do not touch each other. And the narrow section is opened in one of the circumferential groove 2 which forms the block row 7 and the wide section 9 in the other circumferential groove 2 respectively. Also, the length in the tire width direction W1 and W2 of both the sections 8 and 9 is set more than 20% of the width W0 of a block 6. By this constitution, wet performance and abrasion resistance can be improved.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to a pneumatic tire, which is mainly applied to cargo handling vehicles and exhibits excellent wet properties and wear resistance. be.

(Conventional technology) As pneumatic tires applied to cargo handling vehicles such as trucks and vans, there are conventionally widely used pneumatic tires that emphasize wear resistance, such as block pattern tires that emphasize wear resistance, and block pattern tires that emphasize wet performance. has been done.

Here, the rib pattern tire, as shown in Figure 2,
This is achieved by forming only a circumferential main groove in the tread that continues in the circumferential direction of the tire, minimizing movement of the tread when the tire is in contact with the ground during load transfer, thereby improving wear resistance. It functions to improve sexuality. Therefore, this rib pattern tire does not have lateral grooves extending across the lip.

On the other hand, block pattern tires, as shown in FIG. 3, are structured by forming not only circumferential grooves continuous in the circumferential direction of the tire but also lateral grooves extending in the width direction of the tire. In particular, it functions to provide excellent wet traction by cutting the water film on the wet road surface with the block edges formed by the lateral grooves.

(Problem to be Solved by the Invention) However, in such conventional technology, functions and pattern series are clearly separated, such as a rib system for improving wear resistance and a block system for improving wet performance. Therefore, it was extremely difficult to achieve both of these functions with a single tread pattern.

In other words, with rib pattern tires that have excellent wear resistance, there is no block edge that effectively contributes to wet traction, so wet performance is unavoidable. Due to the low pressure, on wet road surfaces with a thick water film,
Hydropregnancy is likely to occur. On the other hand, in a block pattern tire that has excellent wet performance, the blocks have lower rigidity than the ribs and have higher ground contact pressure, which inevitably leads to a decrease in wear resistance.

This invention was made with attention to these problems, and provides a pneumatic tire that achieves both improved wear resistance and improved wet performance, that is, a rib-based pattern and a block-based pattern. By integrating these problems to a high degree without making them obvious, under the ground contact condition during load rolling, it continues as if it were a rib, while sufficiently increasing the contact pressure and providing wet traction. To provide a pneumatic tire that can sufficiently secure the

(Means for Solving the Problems) The pneumatic tire of the present invention has at least two circumferential main grooves continuous in the tire circumferential direction formed in the tread portion,
The tread portion is divided into a central region located between the circumferential main grooves and respective side regions adjacent to the central region, and a plurality of transverse grooves extending in the width direction of the tire are provided in the central region. A pneumatic tire is provided with a row of blocks each formed of blocks, and each transverse groove is defined by a narrow portion where the groove walls contact each other under the ground contact condition during load rolling of the tire, and a groove. It is formed with a wide part where the walls do not touch, and the narrow part is placed in one circumferential main groove.
Further, a wide portion that is continuous with the narrow portion is opened in the other circumferential main groove.

(Function) In this pneumatic tire, when the tire is in contact with the ground while rolling under load, the groove walls of the narrow portions of the transverse grooves come into contact with each other, especially in the central area ε of the tread. As a result, the block row functions as a rib, and the movement of the block row on the ground surface is effectively suppressed, thereby preventing unnecessary wear of the rubber and greatly improving the wear resistance.

On the other hand, the wide part of the transverse groove allows the block edge to cut the water film, since the groove walls are always separated, and also increases the contact pressure of the block, thus preventing hydroplaning. The occurrence of the phenomenon will be effectively suppressed.

By the way, since the groove walls of the narrow part of the transverse groove are separated from each other at the position immediately before contact with the ground, the block edges formed therein also contribute to cutting the water film on the wet road surface. This makes it possible to further improve wet performance.

Moreover, here, the narrow part is opened into one circumferential main groove, and the wide part is opened into the other circumferential main groove,
Moreover, by making both parts continuous with each other, each block is completely defined by the transverse groove, and the load of the vehicle immediately below the ground contact is reduced, including the narrow part where the groove walls contact each other under the ground contact surface. The ground contact with the road surface does not deteriorate due to fluctuations and other disturbances.

In addition to the above, by opening each of the narrow portions and the wide portions alternately in one circumferential main groove in the circumferential direction of the tire, each block under the ground contact condition can be When the block rows are continuous in a zigzag pattern, the rigidity of the block rows can be made sufficiently uniform in the tire circumferential direction, and the risk of uneven wear can be advantageously eliminated.

It should be noted that each side region adjacent to the central region of the tread portion may not only be provided with ribs, but also have a block row similar to that of the central region. However, in the latter case, the wet performance
Each will be improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a tread pattern showing one embodiment of the present invention.

Note that the internal structure of the tire is the same as that of a general radial tire for trucks and vans, so illustration thereof is omitted here.

In the illustrated example of a tire with a size of 185R14, three circumferential main grooves 2 continuous in the tire circumferential direction are formed in the tread portion 1, and the tread portion 1 is positioned between the circumferential main grooves. The tire is divided into a central region 3 and respective side regions 4 adjacent to the central region 3, and within the central region, each land portion defined by each circumferential main groove 2 is Transverse groove 5 extending in the width direction
A block row 7 is made up of blocks 6 each formed by a plurality of blocks.

Further, each transverse groove 5 is formed of a narrow portion S where the groove walls contact each other and a wide portion 9 where the groove walls do not contact each other under the ground contact condition when the tire is rolling under load. Narrow part 8
into the circumferential main groove 2 located on one side of the block row 7,
Moreover, the wide portions 9 that are continuous with the narrow portions 8 are opened into the circumferential main grooves 2 located on the other side of the block row 7, respectively.

According to this, when the tire is in contact with the ground during load rolling, the block rows 7 function as if they were ribs, especially under the action of the narrow portions 8 where the groove walls are in contact with each other. Therefore, as described above, sufficient wear resistance of the tread portion and, by extension, the central region can be ensured.

Furthermore, since the groove walls of the wide portion 9 are still separated even when the tire is in contact with the ground during load rolling, the block edges formed in the wide portion 9 can prevent water film on the wet road surface. Not only can sufficient cutting be performed, but also the ground pressure of each block 6 can be increased to such an extent that the water film can be sufficiently crushed, thereby ensuring excellent wet performance.

Note that the groove walls of the narrow portion 8, which can be selected to have a groove width in the range of 0.3 to 2.0 mm, contact each other under the grounding condition, but are separated from each other until immediately before the grounding. Therefore, the block edge formed at the narrow portion 8 can also effectively contribute to cutting the water film.

In addition, by making the narrow portion 8 and the wide portion 9 of the transverse groove 5 continuous with each other, and opening each of them into the circumferential main groove 2 on the opposite side to the block row 7, Since the block 6 is completely covered by the grooves, including the narrow part where the groove walls contact each other under the ground contact surface, the ground contact surface can be brought into contact with the road surface flexibly against disturbances such as vehicle load fluctuations. It is effective and it is possible to maintain constant running performance.

Moreover, in this example, by opening each of the narrow portions 8 and the wide portions 9 alternately into one circumferential main groove 2 in the tire circumferential direction, each block 6 is By continuing the block rows 7 in a zigzag manner in the circumferential direction, the rigidity of the block rows 7 can be made sufficiently uniform in the tire circumferential direction, and uneven wear can be effectively prevented from occurring.

Furthermore, if the planar shape of each block 6 in the block row 7 is approximately V-shaped or U-shaped as shown in the figure, the angular force of the block edge with respect to the tire circumferential direction will rise to the right within the block. / This is canceled out when going up to the left (naturally, even on the entire tread surface), and it is possible to suppress vehicle deviation, such as steering wheel slipping, caused by the force generated when the block edge contacts the road surface.

Furthermore, when the length of each block 6 in the tire circumferential direction is made substantially equal at each position in the width direction as shown in the figure, the rigidity of the blocks in the circumferential direction is approximately equal. When considering deformation of the block due to driving force, etc., the forces acting on the block in the width direction are approximately equal, and abnormal wear within the block can be suppressed.

Here, for example, the width T of the tread portion 1 is 167 mm,
The width H0 of each block 6 in each block row 7 is 34.
mm, the width of the narrow portion 8 of the transverse groove 5 is 0.
．． 78, the width of the wide portion 9 can be 3.5 mm, and the length of each of them in the block width direction is 1.5 mm. −
2 can be 16III1 and 14 cabinets.

Here, each of these lengths W. , W. When the ratio of both to the width 10 is 20% or more,
The respective functions of the narrow portion 8 and the wide portion 9 described above can be fully and effectively exerted, and this means that
This is particularly noticeable when the two portions 8.9 are continuous at the center of the width of the block row 7.

That is, if the ratio of either one is set to 20% or less, the ratio of the other will exceed 80%, and the block row 7 will significantly approximate either a block pattern or a rib pattern. Both patterns cannot be effectively combined.

Further, in this example, by extending each circumferential main groove 2 in a somewhat zigzag shape in the tire circumferential direction, blocks 6 adjacent in the circumferential direction of the tire can be moved in the tire width direction, for example, by 3M relative to each other. Offset. Here, this offset amount W3 is 5 to 30 with respect to the block width W0.
It is preferable to set it as the range of %.

This is because if the offset amount W3 is less than 5%, no effect of the block edge on the wet road surface can be expected, and if it exceeds 30%, there is a high possibility that uneven wear will occur.

Furthermore, in this example, by setting the length l of each block 6 in the tire circumferential direction to 20 degrees, the ratio of the length l to the block width h0 is set to 59%.

By the way, this ratio can be selected as appropriate in the range of 20 to 200%; increasing the ratio will improve the wear resistance, and decreasing the ratio will improve the wet performance, but if it is less than 20%, the tire tread surface As the ratio of transverse grooves increases, that is, the wide groove portion increases, the pattern becomes more of a wet overlap, and when it exceeds 200%, it approaches a rib-like pattern and becomes a wear overlap pattern.

In addition, as mentioned above, it is preferable that both end faces of each block 6 be parallel to the tire equatorial plane in consideration of drainage performance when driving on a wet road. It is preferable to chamfer the corners with curved or flat surfaces to prevent the corners from collapsing under load and to obtain uniform wear within the block.

The central area 3 of the tread portion 1 has been explained above.
In addition to forming ribs as shown in the figure in each side region 4 adjacent to the circumferential main groove 2 via the circumferential main groove 2, a block row similar to that described above may be formed as required. It is possible.

It is preferable to provide each of the land parts of the tread part 1 formed in this manner with cuts r1 to r@ as shown in the drawings in order to improve the conformability of the land parts to the road surface.

[Comparative example]

A comparative test regarding wear resistance and wet performance between the invention tire and the conventional tire will be explained below.

◎Test tire 0 size 185 R 14 Inventive tire Tire O Conventional tire having the tread pattern shown in Fig. 1 and the various dimensions mentioned above Rib pattern tire 0 Conventional tire having the tread pattern shown in Fig. 2■ Block pattern tire having the tread pattern shown in Fig. 3 ◎Test method/Abrasion resistance Evaluation was made by measuring the amount of tread wear after 50,000 actual driving with a truck with a bed fully loaded with a live load It.

・Wet performance On wet asphalt roads with a water depth of 2.
The vehicle was evaluated by fully braking while driving at m/h and measuring the distance from the start of braking to the stop.

◎Test Results The above test results are expressed in the table below using an index of 100 for the conventional tire I.

It should be noted that the larger the index value, the better the result.

According to this table, compared to the conventional tire I, which has excellent wear resistance, the invented tire has wet performance comparable to that of the block pattern tire (conventional tire ■) without significantly reducing its wear resistance. I understand what can be improved.

(Effects of the Invention) Thus, according to the present invention, the disadvantages of both the rib pattern and the block pattern are made latent, while only their advantages are brought to light, and excellent wear resistance and wet performance can be sufficiently achieved. can be secured.

[Brief explanation of drawings]

FIG. 1 shows a block pattern showing an embodiment of the present invention, and FIGS. 2 and 3 show patterns, respectively. l...Tread portion 2...Circumferential main groove 3...
・Central area 4...Side area 5...Transverse groove 6...Block 7...Block row
8...Narrow width part 9...Wide width part 10...Block width mountain...Length in the tire width direction of the narrow part H1...Length in the tire width direction of the wide part 11...Offset amount l ...Block diagram 2 showing a conventional example of the length of the block in the tire circumferential direction

Claims (1)

[Claims] 1. At least two circumferential main grooves continuous in the circumferential direction of the tire are formed in the tread part, and the tread part is divided into a central area located between the circumferential main grooves, and a central area located between the circumferential main grooves. A pneumatic tire is provided with a block row formed by a plurality of transverse grooves extending in the width direction of the tire in the central region, the pneumatic tire being divided into side regions adjacent to the pneumatic tire. Each transverse groove is formed with a narrow part where the groove walls contact each other and a wide part where the groove walls do not contact each other when the tire is in contact with the ground during load rolling. A pneumatic tire in which a directional main groove opens and a wide part that is continuous with a narrow part opens into the other circumferential main groove. 2. The tire according to claim 1, wherein narrow portions and wide portions of the transverse groove are alternately opened in the circumferential main groove around the tire circumference. 3. The tire according to claim 1 or 2, wherein each length of the narrow width portion and the wide width portion in the tire width direction is 20% or more of the width of the block. 4. The tire according to any one of claims 1 to 3, wherein the narrow portion and the wide portion of the transverse groove are continuous at approximately the center of the width of the block row. 5. The circumferential main groove extends in a zigzag shape in the tire circumferential direction, and blocks adjacent in the tire circumferential direction are relatively offset in the tire width direction within a range of 5 to 30% of the block width. The tire according to any one of claims 1 to 4. 6. The tire according to any one of claims 1 to 5, wherein the planar shape of each block is substantially V-shaped or U-shaped. 7. The tire according to any one of claims 1 to 6, wherein each block has substantially the same length in the tire circumferential direction at each position in the width direction. 8. The tire according to any one of claims 1 to 7, wherein the length of each block in the tire circumferential direction is in the range of 20 to 200% of the block width.