JPH10100615A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that can prevent heel and toe wear while maintaining performance on the wet road surface. SOLUTION: The tread face 2 is provided with three or more longitudinal grooves 5 that are one or more center side longitudinal grooves 3 continuous in the circumferential direction of a tire, and two outer longitudinal grooves 4 on the tread end sides. The tread face 2 is thereby divided in a center area Cr between the groove center of the outer longitudinal grooves 4, and shoulder areas Sh between the groove center of the outer longitudinal grooves 4 and the tread edges E. Each shoulder area Sh is provided with an auxiliary groove 6 extended continuously in the circumferential direction with groove width G3 smaller than the groove width G2 of the outer longitudinal groove 4 so as to divide each shoulder area Sh in an inner tread area 7i placed between the longitudinal groove 5 and the groove center of the auxiliary groove 6, and an outer tread area 7o placed between the tread edge E and the groove center of the auxiliary groove 6. The outer tread area 7o is provided with lateral grooves 9 communicated with the tread grounding end from the auxiliary groove 6, and the inner tread area 7i is unintermittently continuous in the circumferential direction of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of preventing heel and toe wear while maintaining performance on a wet road surface.

[0002]

2. Description of the Related Art When a block row in which blocks are arranged in a tire circumferential direction is formed on a tire tread surface, so-called heel and toe wear (hereinafter, referred to as "H / to T wear)).

In general, when the block comes into contact with the ground, for example, when a braking force or the like is applied thereto, the contact pressure on the rear end portion of the block is increased due to the lifting of the leading end of the block. Then, in such a state, the cause is that wear is concentrated on the rear attachment portion of the block when the rear arrival side of the block slides on the road surface. When a driving force is acting, wear on the block first arrival side is promoted. Further, such H / T wear is likely to occur in the shoulder region of the tire.

[0004] In order to prevent such H / T wear, it is important to suppress the circumferential movement of the block that is in contact with the ground when receiving a braking force and a driving force. Conventionally, techniques for preventing H / T wear include, for example, providing a so-called tie bar having a raised groove bottom between blocks in the tire circumferential direction, and increasing the hardness of tread rubber.
Further, it has been proposed to increase the pattern rigidity of the block itself.

[0005]

However, in the case of simply providing a tie bar, the groove volume is reduced, and the performance particularly on a wet road surface is greatly reduced. In addition, a sufficient effect is still obtained in other proposals. At present, it has not yet been able to demonstrate.

The present invention has been devised in view of the above problems, and has as its object to provide a pneumatic tire capable of preventing the occurrence of H / T wear without deteriorating the running performance on a wet road surface. .

[0007]

Means for Solving the Problems In the present invention, claim 1 is provided.
The described invention provides three or more longitudinal grooves on the tread surface, one or more central longitudinal grooves continuous in the tire circumferential direction and two outer longitudinal grooves on the tread end side. With a central area between the groove centers of the outer vertical grooves and a shoulder area between the groove center of the outer vertical grooves and the tread edge, with a groove width smaller than the groove width of the outer vertical grooves. The shoulder region is sandwiched between a groove center of the subsidiary groove and an inland region sandwiched by the longitudinal groove, and a groove center of the subsidiary groove and a tread edge by a sub-groove continuously extending in the circumferential direction of the shoulder region. It is divided into an outer land area, and the outer land area is provided with a lateral groove communicating from the sub-groove to a tread contact end, and the inland area is continuously connected in the tire circumferential direction without interruption. It is a pneumatic tire.

[0008] According to a second aspect of the present invention, the sub-groove includes:
The center of the groove is at least 20% and 40% or less of the shoulder contact width from the outer peripheral edge of the outer longitudinal groove in the tire axial direction to the contact end of the tread contact surface on the outer side in the tire axial direction. It is provided at a position separated from the edge, and the groove depth is 10% or more and 50% or less of the groove depth of the vertical groove.

In the invention according to claim 3, the width of the sub-groove is not less than 1.5 mm and not more than 2.5 mm.

Further, in the invention described in claim 4, the inland area is formed of ribs that are continuous with substantially the same width and have no horizontal grooves, and all land portions sandwiched between the vertical grooves in the central area have At least one end is provided with a horizontal groove communicating with the vertical groove, and the invention according to claim 5 is characterized in that the vertical grooves are all linear grooves.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The pneumatic tire of the present invention has a tread surface 2 as shown in FIG.
And one or more (two in this example) continuous in the tire circumferential direction
And a total of three or more (four in this example) vertical grooves 5 of the center side vertical groove 3 and the tread end side two outer vertical grooves 4.

As shown in FIG. 2, the pneumatic tire has a tire size having, for example, a carcass 15 having a radial structure and a belt layer 16 disposed radially outside the carcass 15 and inside the tread portion. 195 / 65R1
5 shows an example of a radial tire.

The vertical groove 5 is formed appropriately in a groove width measured on the tread surface 2 within a range of, for example, 2 to 15% of the tread contact width TW, more specifically, 3 to 20 mm. Although the vertical grooves 5 are all formed as straight grooves in order to enhance the performance, various shapes such as a zigzag shape and a wave pattern may be adopted.

The "tread contact width" is a distance between the outer ends in the axial direction where the tread surface 2 is in contact with the rim on a regular rim, is filled with the regular internal pressure, and the standard maximum load is applied. Define.

The vertical groove 5 is preferably formed to have a uniform depth of 5 mm or more and 18 mm or less, in this example, about 8 mm.

Further, the longitudinal grooves 3, 3 on the central side are arranged at positions on both sides of the tire equator C where the contact pressure is relatively high. Therefore, in order to improve drainage, the groove width is larger than the outer vertical grooves 4 and 4, specifically, the groove width G1 of the central vertical groove 3 is 6 mm, and the groove width G2 of the outer vertical groove 4 is 2 mm. Is 3 mm. That is, the groove width G1 of the central vertical groove 3 is formed to be about twice as large as the groove width G2 of the outer vertical groove 4.

The tread surface 2 is formed by a plurality of vertical grooves 5 with a central area Cr between the center of the outer vertical grooves 4 and a shoulder area between the center of the outer vertical grooves 5 and the tread edge E. Sh
In this example, the vertical grooves 5 are arranged at symmetrical positions with respect to the tire equator C.

In the present embodiment, the width Lc of the central region Cr in the tire axial direction occupies about 60% of the tread contact width TW, but other than that, preferably the range is about 50 to 80%. Can be determined as appropriate.

In the present embodiment, the central region Cr is the tire equator C
By arranging two central longitudinal grooves 3 on both sides of
A land portion including a rib portion 12 passing through the tire equator C and block row portions 13 on both sides thereof is formed. In this example, a horizontal groove 19 having one end or both ends communicating with the vertical groove 5 is provided between the rib portion 12 and the block row portion 13 to improve wet performance.

The shoulder region Sh is formed in the outer vertical groove 4.
The inland area sandwiched between the center of the sub-groove 6 and the center of the outer vertical groove 4 by the sub-groove 6 extending continuously in the circumferential direction through the shoulder region Sh with a groove width G3 smaller than the groove width of 7i
And a land area 7o sandwiched between the groove center of the sub-groove 6 and the tread edge E.

The outer land area 7o is provided with horizontal grooves 9 communicating from the sub-groove 6 to the tread contact end, and the inland area 7i is continuous in the tire circumferential direction without interruption. FIG. 2 shows a continuous rib 10 having substantially the same width.

Thus, in the shoulder region Sh,
The outer land area 7o is provided with a lateral groove 9 communicating from the sub-groove 6 to the tread contact end (tread edge E), and the inland area 7i is continuously connected in the tire circumferential direction without interruption. Block 11 formed in land area 7o
The movement in the tire circumferential direction at the contact width of the tire can be suppressed by the inland area 7i continuous in the tire circumferential direction, and the block 11
H / T wear can be prevented from occurring.

When the inland area 7i is interrupted in the tire circumferential direction, it becomes difficult to suppress the movement of the blocks in the outboard area 7o. Here, the term “interruption” of the inland portion 7i means that the lateral groove having a groove width of 2 mm or more and a groove depth of 5 mm or more communicates with the outer vertical groove 4 and the sub-groove 6.
It means that i is divided in the tire circumferential direction.

Therefore, in the inland area 7i, for example, a groove or the like having a groove width and a groove depth of about 1 mm may be formed to have a recess extending in the tire axial direction. However, preferably, a groove or the like is provided in this embodiment. It is formed as a rib having substantially the same width and the same height without being extended.

In the sub-groove 6, the center of the groove is a grounding end of the outer vertical groove 4 from the outer edge 4A in the tire axial direction (shown in FIG. 2) of the tread ground surface to the outer side in the tire axial direction. In this case, it is preferable that a distance f not less than 20% and not more than 40% of the shoulder contact width Sw to the tread edge E is provided at a position separated from the outer edge 4A.

The distance f is equal to 20 of the shoulder contact width SW.
%, The inland area 7i becomes narrower, and it becomes difficult to suppress the movement of the block 11 in the outer area 7o. Conversely, if it exceeds 40%, the inland area 7i becomes wider,
Rigidity is excessively increased and ride comfort is reduced. In addition, the length of the lateral groove 9 in the land area 7o is reduced to reduce the groove volume.
None of them is preferable, for example, the ET performance tends to be reduced.

For the same reason as described above, the groove width G3 of the sub-groove 6 is desirably 1.5 mm or more and 2.5 mm or less, and is preferably a straight groove like the vertical groove 5. The groove 6 has a groove depth of 10% or more of the groove depth of the vertical groove and 5% or more.
It is preferably set to 0% or less.

The groove depth of the sub-groove 6 is 10 times the groove depth of the vertical groove.
%, The edge component formed by the groove edge and the tread surface does not provide a sufficient edge effect of shaving the water film, and tends to lower the WET performance. Conversely, when the groove depth of the sub-groove 6 exceeds 50% of the groove depth of the vertical groove 5, the block 11 in the outer land area 7o easily moves independently in the tire circumferential direction with respect to the inland area 7i. H / T
Poor effect of suppressing wear.

By providing the inland area 7i, the communication between the horizontal groove 9 and the vertical groove 5 is interrupted, and there is a concern that the drainage property may be deteriorated. The groove volume and the edge component of the block 11 can be maintained or increased, and a decrease in wet performance can be prevented.

The lateral groove 9 and the lateral groove 19 have, for example, a groove width of 2 mm or more and 15 mm or less and a groove depth of 7
It is about 0 to 100%. In this example, the sub-groove 6 is provided to increase the groove volume as a whole, so that the lateral groove 9 has a groove width of about 40 to 60% in the axially inner portion from the middle position in the tire axial direction length. In this example, the narrow width portion 9A is reduced by 50%. As a result, the blocks 11 between the lateral grooves 9 increase the rigidity of the inner portion in the tire axial direction, and together with the ribs 10 in the inland area 7i,
This is preferable in that the movement in the tire circumferential direction can be further reduced.

[0031]

EXAMPLE A tire having a tire size of 195 / 65R15 and having a tread pattern as shown in FIGS. 1 and 2 was prototyped according to the present invention (Example 1). Central area C of 2
As for r, the following test tires (all without a sub-groove) similar to those in Example 1 were also prototyped, and the performance was evaluated.

Conventional Example: Shoulder region Sh is shown in FIG.
(A) As shown in FIG. Comparative Example 1: A shoulder area Sh is formed by providing a tie bar 9B between the blocks 11, 11 as shown in FIG. Comparative Example 2: The shoulder region Sh has a configuration in which a narrow portion 9A having a small groove width is formed in the lateral groove 9 over about 50% of the groove length, as shown in FIG. 4A. Comparative Example 3: One in which a discontinuous lug groove 9C is provided in the shoulder region Sh as shown in FIG. The test method is as follows.

(1) H / T abrasion test In the test, the test tire was mounted on the front wheel of a rear-wheel-drive test vehicle, and the test course was braked at a speed of 100 km / h at a speed of 0.45 G (four times / 3 km). When the running distance was 500 km, the difference between the maximum abrasion amount at both circumferential edges of the block in the shoulder region and the minimum abrasion amount at the center of the block was measured as H / T abrasion amount.

(2) Straight-line hydro performance The vehicle enters and brakes (locks) while gradually increasing the speed on a straight course having a puddle with a depth of 10 mm on the asphalt road surface, and the deceleration G is measured. The speed at which the deceleration G becomes 0.15 G is indicated by an index. The higher the value, the better.

(3) Sensory evaluation of pattern noise As reference data, 5 points at a speed of 60 km / h on a straight test course (asphalt road surface) using the test vehicle.
The vehicle was coasted at a distance of 0 m, and the pattern noise was evaluated by a five-point method according to the driver's feeling. Table 1 shows the test results.

[0036]

[Table 1]

As a result of the test, the tire according to the embodiment showed a H / T
It can be confirmed that the wear amount is reduced. Comparative Example 4
It was found that although the H / T abrasion amount was smaller than that of the example, the wet performance was significantly reduced due to the lug pattern.

Next, when the position of the sub groove 6 of the tire of the present invention was variously changed (Examples 1 to 5), the performance was evaluated by the following test.

(4) Amount of slip The distance that one point on the block 11 has moved on the ground contact surface immediately after it touches the road surface and before it leaves the road surface is indicated by an index with the conventional example being 100. I have. Under the same contact pressure, the larger the value, the larger the H / T wear amount.

(5) Ride Comfort As described above, comprehensive sensory evaluation was performed on the dry asphalt road surface with regard to ruggedness, thrust, and dumping. is there. Note that the H / T wear amount and the linear hydro are the same as in the previous case. Table 2 shows the test results.

[0041]

[Table 2]

As a result of the test, the position of the sub-groove is such that the center of the groove is 20% of the shoulder contact width Sw.
It was found that Example 1 in which the distance not less than 40% was provided at a position separated from the outer edge of the outer longitudinal groove was most preferable with good overall balance. In Example 5, in which the groove depth of the sub-groove was set to 80% of the groove depth of the vertical groove, the effect of suppressing the amount of H / T abrasion tended to be small.

[0043]

As described above, the pneumatic tire of the present invention has the following features.
Without deteriorating running performance on wet road surfaces,
T wear can be prevented.

[Brief description of the drawings]

FIG. 1 is a development view of a tread pattern showing an embodiment of the present invention.

FIG. 2 is a right sectional view of the tire showing the embodiment of the present invention.

FIGS. 3A and 3B are a development view and a sectional view showing a shoulder region of a conventional example and a comparative example, respectively.

FIGS. 4A and 4B are a development view and a sectional view showing a shoulder region of a conventional example and a comparative example, respectively.

[Explanation of symbols]

 2 Tread surface 3 Central longitudinal groove 4 Outside longitudinal groove 5 Vertical groove 6 Secondary groove 7i Inland area 7o Outland area 9 Lateral groove 10 Rib 11 Block Cr Central area Sh Shoulder area TW Tread contact width Sw Shoulder contact width

Claims (5)

[Claims] 1. A tire having a continuous tread surface in the tire circumferential direction.
By providing three or more flutes, i.e., one or more central flutes and two outer flutes on the tread end side, a central area between the center of the outer flutes and an outer flute is provided. By dividing into a shoulder region between the groove center of the vertical groove and the tread edge, a sub-groove extending continuously in the circumferential direction through the shoulder region with a groove width smaller than the groove width of the outer vertical groove, The shoulder area is divided into an inland area sandwiched between the groove center of the sub-groove and the longitudinal groove, and an inland area sandwiched between the groove center of the sub-groove and the tread edge, and the outer land area is A pneumatic tire, wherein a lateral groove communicating from the sub-groove to the tread contact edge is provided at a distance, and the inland area is continuous in the tire circumferential direction without interruption. 2. The auxiliary groove, wherein the center of the groove is at least 20% of a shoulder contact width from a tire axially outer edge of the outer longitudinal groove to a tire axially outward contact end of a tread contact surface, and The pneumatic tire according to claim 1, wherein a distance of 40% or less is provided at a position separated from the outer edge, and the groove depth is 10% or more and 50% or less of the groove depth of the vertical groove. 3. The groove width of the sub-groove is 1.5 mm or more.
3. The pneumatic tire according to claim 1, which is not more than 5 mm. 4. The inland area is composed of ribs that are continuous with substantially the same width and have no horizontal grooves, and at least one end of each of the land portions sandwiched between the vertical grooves in the central area communicates with the vertical grooves. 4. The pneumatic tire according to claim 1, wherein lateral grooves are provided. 5. The pneumatic tire according to claim 1, wherein all the vertical grooves form straight grooves.