JP2966760B2 - Heavy duty tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention can be suitably used as an all-weather tire, and has abrasion resistance while maintaining performance on ice and snow.
The present invention relates to a heavy duty tire capable of improving uneven wear resistance.

[0002]

2. Description of the Related Art In recent years, all-weather tires capable of properly capturing the road surface even on snowy or icy roads where snow and ice have formed while maintaining the running performance on dry good roads have been used for heavy loads such as trucks and buses. It is often used in vehicles. As a typical tread pattern of this type of tire, for example, as described in JP-A-3-128705, a region between two circumferential main grooves provided on both sides of the tire equator is defined by a circumferential direction. It is known that the blocks are divided into a large number of blocks by grooves and lateral grooves, and in order to obtain good performance on ice and snow, the shape and dimensions of the blocks themselves are reduced and the number of blocks is increased. The edge component is increased by providing a siping on the edge.

[0003]

However, such fragmentation of the blocks and formation of sipes cause the block to move under running under a high load such as a heavy duty tire due to the movement of the blocks during running, and impair the wear resistance and increase the heel. There is a problem that uneven wear such as and toe wear is easily induced.

According to the present invention, the blocks are subdivided on the basis of specifying the positions of the vertical main grooves provided on both sides of the equator of the tire and dividing a block formed between the vertical main grooves by a narrow groove having a specified groove width. It is an object of the present invention to provide a heavy-duty tire that can improve the wear resistance and uneven wear resistance when solving the problem and can solve the above problem.

[0005]

According to the present invention, there is provided a heavy-duty tire according to the present invention, wherein a vertical main groove extending in a circumferential direction of a tire is provided on both sides of a tire equator so that a tread contact surface is formed with the vertical main groove. And a distance L from the tire equator C at the center of the vertical main groove to the tire tread width SW of 0.25-0. 40 times, and the center contact surface area is set to 0.10 to gross width WG of the vertical main groove.
A vertical groove having a groove width of 0.60 times and extending in the circumferential direction of the tire, and a horizontal groove extending in a direction intersecting with the vertical groove are formed as an area composed of a block dividing the central ground contact area. I have.

Preferably, the groove depth Dy of the lateral narrow groove is 0.10 to 0.33 times the groove depth DG of the vertical main groove, and a siping is provided at the bottom of the lateral narrow groove. And the sum Dy of the depth Ds of the siping and the groove depth Dy of the lateral narrow groove
+ Ds to 0.80 to 1.2 of the groove depth DG of the vertical main groove.
It is better to double.

[0007]

According to the tread pattern of the present application, a block is formed in a central contact surface area having a high contact pressure and divided by a vertical main groove. This block has a groove width WG of 0.6 of the vertical main groove.
Because it is divided by vertical and horizontal grooves of 0 times or less, even when the blocks are downsized and the number of blocks is increased, the decrease in land ratio is eased and relatively high pattern rigidity is maintained. Since the position of the groove is specified in the distance range of 0.25 to 0.40 times the contact surface width SW,
Wear progress in the central ground contact area and the shoulder ground contact area can be made uniform, and the wear resistance and uneven wear resistance can be improved by a synergistic effect of these.

In addition, since the vertical and horizontal grooves are used, when forming a block pattern with the same land ratio, the number of blocks is improved along with the edge length, and the drainage performance and the performance on ice by scratching the road surface are improved. . In addition, since the block is formed in the central contact surface area where the contact pressure is high, the block penetrates into the snow greatly, the adhesive friction with the ice surface is increased, and it is compared with the case where siping is formed in the block. As a result, since the block rigidity is maintained, the above-mentioned performance on ice and snow is ensured even in a heavy load tire. In addition, since the groove volume is reduced, the sound pressure of the pumping sound is reduced, which can contribute to noise reduction.

Further, the depth of the horizontal narrow groove is set to 0.3 of the vertical main groove depth DG.
When it is 3 times or less, the effect of maintaining the rigidity of the block in the circumferential direction is further enhanced, and the wear resistance and uneven wear resistance can be further improved. At this time, it is preferable to form a siping of a predetermined depth at the bottom of the lateral narrow groove in order to prevent loss of wettability and on-ice property due to early wear of the lateral narrow groove. Good wettability and on-ice properties are ensured until the end of life due to the edge effect of siping that appears after attrition.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a heavy load tire 1 includes a tread portion 2
And sidewall portions 3 extending inward in the tire radial direction from both ends thereof, and bead portions 4 disposed at radially inner ends of the respective sidewall portions 3. In the present example, for example, a tire size 11R22.5 Is formed as a radial tire.

The tire 1 includes a toroidal carcass 6 extending between the bead portions 4 and a belt layer 7 disposed radially outside the carcass 6.

The carcass 6 is formed of one or more, for example, two carcass plies which are turned around the bead core 5 of the bead portion 4 from the tread portion 2 to the side wall portion 3. The carcass cords are arranged at an angle of 75 to 90 degrees with respect to the tire equator C. In this example, a steel cord is used as the carcass cord. The carcass may be composed of a plurality of plies using an organic fiber cord such as an aromatic polyamide, nylon, rayon, or polyester in addition to a steel cord. The folded portion 6a of the carcass 6 is interrupted above the bead core 5 and below the maximum width position of the tire. Between the folded portion 6a and the main body 6b, a triangular cross-section rising from the bead core 5 to the outside in the radial direction is provided. The bead apex rubber 8 is filled to reinforce the bead portion 4 and increase the lateral rigidity of the tire.

The belt layer 7 includes a plurality of belt cords arranged at an angle of 15 to 80 degrees with respect to the tire equator C,
In this example, the belt cord is composed of, for example, four belt plies, and a low-stretch metal fiber cord such as steel is preferably used as the belt cord. Also, as the belt cord, high-strength organic fiber cord such as aromatic polyamide,
It can be selected according to the required tire performance.

As shown in FIG. 2, the tread portion 2 is provided with two vertical main grooves G extending in the circumferential direction of the tire on both sides of the tire equator C. The central contact surface area S1 is divided into a central contact surface area S1 between the grooves G, G and a shoulder contact surface area S2 on the outer side in the tire axial direction. It is formed as an area composed of blocks B defined by horizontal narrow grooves y that intersect with the narrow grooves.

Here, the tread contact surface S is an area where the tread surface TS, which is the outer surface of the tread, contacts the road surface when the tire is mounted on a standard rim, filled with a standard internal pressure and a standard load is applied. And the standard rim and standard internal pressure are JATMA, TRA, ETR
The standard rim and the maximum air pressure of each tire and the standard load defined by the standards such as TO are defined as the maximum loads. The tread surface TS has a center on the tire equatorial plane in a meridional section of the tire filled with the standard internal pressure and has a radius of curvature R1 of, for example, 1.1 of the tread width TW.
Curved convexly along an arc of 5 to 5.0 times,
As a result, a profile in which the ground pressure in the central ground surface area S1 is larger than the ground pressure in the shoulder ground surface area S2 is obtained. In addition, both ends of the tread surface TS intersect with the buttress surface BS at, for example, an edge via an inclined surface. Therefore, in this example, the tread surface TS coincides with the tread ground surface S.

As shown in an enlarged view in FIG. 3, the vertical main groove G is formed in a linear or zigzag groove having a groove width WG of 5 mm or more, in this example, a zigzag groove. The zigzag angle α is 6 with respect to the tire circumferential direction.
It is set in the range of ２５25 degrees. The distance L between the groove center of the vertical main groove G and the tire equator C is determined by the tread contact surface S
0.25 to 0.4 times the width SW of
Is measured as the distance from the center of the zigzag deflection at the groove center when the vertical main groove G is in a zigzag shape.

The vertical narrow groove g and the horizontal narrow groove y formed in the central ground contact surface area S1 have their groove widths Wg and Wy set to 0.10-0. In this example, as shown in FIG. 2, the vertical narrow groove g is a central vertical groove ga extending on the tire equator C and the vertical narrow grooves gb on both outer sides thereof. And extend straight in the tire circumferential direction. In addition, the horizontal narrow groove y is the vertical narrow groove ga, g.
b, which divides into block rows in which the blocks Ba are lined up by traversing between the blocks b, and the outer part in which the blocks Bb are lined up by traversing between the vertical narrow grooves ga and the vertical main grooves G. The inner narrow groove ya and the outer narrow groove yb are inclined at an angle of 25 degrees or less, for example, 20 degrees with respect to the tire axial direction. The number of horizontal narrow grooves ya and yb formed in each block row is 120 to 1
80 blocks are preferred, so that each block Ba, Bb
Is formed in a horizontally long and small parallelogram capable of exhibiting high cornering power. In the present example, the horizontal narrow grooves ya and yb are inclined in opposite directions, and between the horizontal narrow grooves ya and yb adjacent to each other in the tire axial direction, and between the horizontal fine grooves ya and ya.
Phase in the circumferential direction between them is approximately の of the pitch length of the lateral narrow groove.
It is shifted by twice the length to improve uniformity.

As described above, the formation position of the vertical main groove G is specified, and the central ground contact area S1 is divided into blocks by the vertical fine grooves g and the horizontal fine grooves y whose groove widths are regulated. Even when the size is reduced and the number of blocks is increased, the decrease in land ratio is alleviated, and relatively high pattern rigidity is maintained. Wear is also reduced due to uniform wear between the center tread area and the shoulder tread area. Properties and uneven wear resistance can be improved.

A tire having a tread pattern as shown in FIG. 6 schematically showing the vertical main groove G, the vertical narrow groove g and the horizontal narrow groove y is shown in Table 1.
A prototype was produced based on the specifications described above, and the tires were compared in terms of wear resistance, uneven wear resistance, and passing noise. The wear resistance is as follows: a tire is mounted on a rear wheel drive shaft, the tire is driven on a general road for a distance of 50,000 km, and the wear amount is measured at each position of the marks M1 and M2. The amount of abrasion at M1 and M2 of the product B of the embodiment was set as a reference (10
0). The larger the index, the better. The uneven wear resistance was as follows: the tire was mounted on the front wheel, the tire was run on a general road for a distance of 5000 km, and the uneven wear amount (depth of uneven wear) at the place where uneven wear occurred was measured. In the table, ○ indicates uneven wear of 5 m
less than m, Δ is 0.5 to 1.0 mm uneven wear, and X is 1.0 mm or more uneven wear. Passing noise is 50km / H with the test tires mounted on all wheels and the engine off.
A microphone is set at a position 7.5 mm laterally away from the vehicle traveling on the vehicle, noise is measured in accordance with JASO standard C606, and the measured value (dB value) is measured in Example B.
Was expressed as an index with reference to (100). The road surface is a dense asphalt concrete road surface, and the larger the index, the better.

[0020]

[Table 1]

As a result, as the distance L of the vertical main groove G from the tire equator C increases, the wear in the shoulder contact surface area S2 increases, while as the distance L decreases, the wear in the central contact surface area S1 increases. Wear increases, and the distance L increases with the ground contact surface width S.
It can be confirmed that in the range of W of 0.25 to 0.40, the wear progress of both the ground contact surface areas S1 and S2 is made uniform, and the wear resistance and uneven wear resistance are improved. The 0.25-0.
Even in the range of 40, the groove width W of the vertical narrow groove g and the horizontal narrow groove y
If g and Wy exceed 0.60 times the groove width WG of the vertical main groove, it is confirmed that the wear in the central tread area S1 is deteriorated and the wear resistance and uneven wear resistance cannot be improved. it can. That is, when the distance L is less than 0.25 SW, when it exceeds 0.4 SW, and when the groove widths Wg and Wy exceed 0.60 WG, the intended effect of improving wear resistance cannot be expected. Further, when the distance L is less than 0.25SW, the air column resonance in the vertical main groove G is excited by tire vibration, and the noise is deteriorated.
In addition, the amount of heat stored in the shoulder contact surface area S2 is increased, thereby inducing belt end peeling or the like, thereby impairing durability. When the distance L exceeds 0.4 SW, the shoulder contact surface area S2 becomes too small to induce shoulder drop wear. Groove width Wg, Wy
Is less than 0.10 WG, the drainage function cannot be sufficiently exhibited.

Further, the vertical main groove G is preferably formed in a zigzag shape as in this embodiment, thereby having a drainage function over the entire width of the zigzag runout, and exhibiting a road surface scratching effect by the groove edge. Helps improve performance and performance on ice. However, when the zigzag deflection angle α is less than 6 degrees, the above-mentioned improvement effect is not expected. On the other hand, when the zigzag deflection angle α exceeds 25 degrees, the rigidity of the top of the zigzag is reduced, which causes pitch sound, and the starting point of the track wear (nucleus) Inducing new uneven wear.

When the number of horizontal narrow grooves ya and yb formed in each block row is less than 120, sufficient wet performance can be obtained.
If the performance on ice cannot be exhibited, and if the number exceeds 180, on the other hand, the size of the block becomes too small, and there is a risk of occurrence of uneven wear. Therefore, the number of formed lines is preferably in the range of 130 to 160 lines.

As shown in FIGS. 2 and 4, the horizontal narrow groove y has a groove depth Dy of 0.10 to 0.15 of the groove depth DG of the vertical main groove.
It has a shallow bottom of 0.33 times, and the bottom of the groove has a width of 0.5 times or more, more preferably 0.7 times or more, of the length K of the horizontal narrow groove y. A siping 9 extending on the center line is formed. The siping 9 is a cut-like body having a siping width in the range of 0.5 to 1.5 mm, and maintains the pattern rigidity in the circumferential direction by closing its opening by a compressive force when the tire is in contact with the ground. If the siping width is less than 0.5 mm, it is difficult to form a siping with a molding die. If the siping width exceeds 1.5 mm, the opening cannot be closed at the time of grounding, and the rigidity is significantly reduced.

By making the lateral narrow groove y shallow, the effect of maintaining the rigidity of the block in the circumferential direction is further enhanced, and the wear resistance and uneven wear resistance can be further improved. When the groove depth Dy of the lateral narrow groove exceeds 0.33 DG, the block rigidity may be insufficient and the uneven wear may be deteriorated to a level that cannot be corrected even in the first tire rotation.

The siping 9 appears on the tread surface TS when the shallow horizontal narrow groove y is worn out, and by its edge effect, ensures good wettability and good ice performance until the end of the tire wear life. Therefore, if the siping length is less than 0.5 times the horizontal narrow groove length K, a sufficient edge effect cannot be generated. Further, the siping 9 has a siping depth D in order to exert the edge effect until the end of the wear life.
The sum Dy + Ds of s and the groove depth Dy of the lateral narrow groove y needs to be 0.80 times or more the vertical main groove depth DG, and the sum Dy + Ds exceeds 1.20 DG. As a result, the thickness of the rubber gauge of the entire tread rubber becomes excessive, and an unnecessary weight increase is caused. Therefore, the sum D
y + Ds is more preferably 0.90 DG or more, and the upper limit is 1.00 DG or less.

The vertical narrow groove g is a groove deeper than the horizontal narrow groove y.
By making it 8 to 1.2 times, drainage is exhibited over the end of the wear life. The groove depth Dg is more preferably not more than 1.0 times the depth DG of the vertical main groove G. If it exceeds 1.0 times, cracks are likely to occur at the bottom of the vertical narrow groove g, and if the rubber gauge below the bottom of the groove is increased to prevent the crack, the tire weight increases.

In the present embodiment, the shoulder contact surface area S2 includes:
Lug groove 1 extending from the vertical main groove G to the buttress surface BS
0 is formed, the lug groove 10 has a shallow bottom portion 10A whose groove depth approximates the groove depth Dy of the lateral narrow groove at the inner portion in the tire axial direction, and the groove depth at the outer portion thereof has the groove depth of the vertical main portion. A deep portion 10B which is similar to the groove depth DG of the groove G is formed, and a siping 11 having the same depth as the siping 9 is formed in the shallow portion 10A. The lug groove 10 is more effective in increasing the block rigidity than a flat-bottom groove having the same groove volume as the lug groove, and also reduces the air column resonance in the groove by changing the height of the groove bottom. It can suppress and improve noise performance.

Further, the siping 11 of the shallow portion 10A, like the siping 9, does not restrict the movement of the rubber along the siping, so that the pattern rigidity in the tire axial direction can be reduced. As a result, especially when turning, It is possible to suppress a decrease in the contact area and make the contact pressure distribution uniform, which helps to maintain the wet performance by improving the contact property.

(Specific Example) A tire having the structure shown in FIGS. 1 and 2 and having a tire size of 11R22.5 was prototyped based on the specifications shown in Table 2, and the abrasion resistance, uneven wear resistance and wettability of the prototype tire were measured. Was measured, and the results are shown in the same table.

The test for wear resistance and uneven wear resistance was carried out in accordance with the test specifications in Table 1 above, and the wear resistance was measured at the position of the mark M3 in FIG. The wettability is a value obtained by indexing the braking distance when the test tires are mounted on all the wheels and the brakes are applied to all the wheels at a speed of 50 km / H on an asphalt road having a water film thickness of 2 mm. The larger the index, the better. The results (numerical values) of the abrasion resistance and the wettability are indexed with the product of Example 2 being 100, and the larger the index value, the better the performance.

[0032]

[Table 2]

[0033]

Since the heavy duty tire of the present invention is constructed as described above, the tire has abrasion resistance while maintaining performance on ice and snow.
The uneven wear resistance can be enhanced, and it can be suitably used as an all-weather tire.

[Brief description of the drawings]

FIG. 1 is a meridional section of a tire showing one embodiment of the present invention.

FIG. 2 is a pattern development view showing an example of the tread pattern.

FIG. 3 is a sectional view showing a vertical main groove.

FIG. 4 is a cross-sectional view showing a lateral narrow groove together with siping.

FIG. 5 is a sectional view showing a vertical narrow groove.

FIG. 6 is a developed view of a tread pattern of the tire used in Table 1.

[Explanation of symbols]

 9 Siping C Tire equator G Vertical main groove g, ga, gb Vertical narrow groove y, ya, yb Horizontal narrow groove S Tread ground plane S1 Central ground plane area S2 Shoulder ground plane area

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-195912 (JP, A) JP-A-60-116511 (JP, A) JP-A-4-189605 (JP, A) JP-A-4-199 138902 (JP, A) JP-A-4-208605 (JP, A) JP-A-62-194909 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60C 11/11-11 / 13 B60C 11/04-11/06

Claims (3)

(57) [Claims] 1. A tread contact surface is provided on both sides of a tire equator C in a circumferential direction of a tire by a tread contact surface between a central contact surface region between the longitudinal main grooves and a shoulder contact surface region outside the tire axial direction. , And the distance L from the tire equator C to the center of the vertical main groove is defined as 0.
25 to 0.40 times, and the central ground contact area has a groove width of 0.10 to 0.60 times the groove width WG of the vertical main groove and extends in the tire circumferential direction. And a heavy-duty tire formed as an area consisting of a block that divides the central ground contact area by a lateral narrow groove extending in a direction intersecting with the vertical narrow groove. 2. The heavy-duty tire according to claim 1, wherein a groove depth Dy of the lateral narrow groove is 0.10 to 0.33 times a groove depth DG of the vertical main groove. 3. The lateral narrow groove has a siping extending along the lateral narrow groove at a groove bottom, and a sum Dy + Ds of a depth Ds of the siping and a groove depth Dy of the lateral narrow groove.
2. The heavy load tire according to claim 1, wherein the depth is 0.80 to 1.2 times the groove depth DG of the vertical main groove. 3.