JPH0310910A - Heavy duty pneumatic tire - Google Patents

Abstract

PURPOSE:To balance both of wet road performance and wear resistance by providing paired grooves with intervals in the direction of tire width while forming plural number of sipes between the respective inner narrow grooves, and by setting three kinds of specified relation for these spaces and the tread width. CONSTITUTION:On a tread 12 of a tire 30, there are arranged two main peripheral grooves 14, paired narrow grooves 16a, 16b, plural number of ribs 32, 34 divided by these grooves, and sipes 36 formed on the respective ribs 32 and 34. In this case, the following relation is set: C=(0.10 to 0.30)XT, W=(0.03 to 0.14)XT, K=(0.05 to 0.50)XA, where T is tread width, C is a distance from an end of the tread to the outer edge of each narrow groove 16b, W is a distance between the respective narrow grooves 16a and 16b, A is a distance between the respective inner narrow grooves 16a, K is a distance between the respective sipes 36 arranged in the peripheral direction of the tire.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a heavy-duty pneumatic tire applied to trucks, buses, etc., in particular, which improves wear resistance without impairing its wet performance. It concerns pneumatic tires.

(Prior art) Installed on heavy vehicles such as trucks and buses.
With regard to heavy-duty pneumatic tires, with the expansion of the expressway network, there is an increasing demand for tires with excellent wear resistance, especially uneven wear characteristics called railway wear or river wear. One of the tires proposed to meet these demands is a tire having a tread pattern shown in FIG.

As shown in FIG. 1(a), this tire 10 has a tread 12 with a plurality of circumferential main grooves 14 extending substantially in the tire circumferential direction and spaced apart from each other.
A pair of narrow grooves 16 are formed at the ends of the sipes 2 and extend in the tire circumferential direction, and a pair of sipes 18 are formed in the shoulders of the sipes 18 and extend in the tire radial direction. A force in the braking direction of the tire, that is, a negative shearing force will be generated in the rib 20 formed by the rib 20.
The tire radial length of the other adjacent rib 22
．． By making the radial length of rib 2 shorter than the length of rib 24,
2.24 The occurrence of uneven wear can be effectively prevented.

However, in this tire, although the occurrence of uneven wear can be effectively prevented by forming the narrow grooves 16 in the tread 12 of the tire, since the groove width of the narrow grooves 16 is narrow, It is not possible to ensure drainage performance, and for this reason, the circumferential main groove 14 as shown in FIG.
The problem of inferior steering stability on wet road surfaces compared to tires having a wet road surface has not yet been satisfactorily solved.

On the other hand, although the tire shown in FIG. 6 has excellent drainage performance, it has a problem in that uneven wear tends to occur.

The present invention has been made in view of such problems,
The purpose of the present invention is to provide a heavy-duty pneumatic tire with improved wear resistance without impairing steering stability in wet conditions.

(Means for Achieving the Object) In order to achieve this object, the tire of the present invention has two sets of tires spaced apart from each other in the tire width direction, extending in the tire circumferential direction and spaced apart from each other. and a plurality of sipes formed at regular intervals in the circumferential direction of the tire between each set of narrow grooves located on the inside in the width direction of the tire. The distance between the narrow grooves located outward in the tire width direction of each set is C1. The distance between the narrow grooves forming a pair of each set is W. The distance between the narrow grooves located inward in the tire width direction of each set is When the interval is W and the interval between sipes spaced apart from each other in the tire circumferential direction is c=o.
, io~0.30×T, W=0.03~0.14×T,
=0.05~0.50×A.

(Function) According to such a tire, uneven wear can be effectively prevented from occurring in the ribs other than the narrow rib defined between the two pairs of narrow grooves, and the uneven wear can be prevented along the circumferential direction of the tire. To enable drainage along sipes formed in an area defined by two sets of narrow grooves while ensuring drainage performance.

Here, when the tread width of the tire is T, the narrow grooves located outward in the tire width direction of each pair are formed within a range of 0.10 to 0.30 x T from the tread edge. This is because if it is smaller than 0.10 x T, the rib rigidity from the tread edge is too weak and the negative shear force does not work effectively, while if it is larger than 0.30 x T, it is too close to the center. This is because the effect on uneven wear of a part of the shoulder is reduced.

In addition, forming pairs of narrow grooves generates a relatively large negative shear force component in the rib portion formed between the narrow grooves, while at the same time This causes the shear force generated in other ribs to shift significantly in the positive direction, and the generation of nuclei that cause uneven wear along the edges of other ribs due to the dragging of the tread rubber that constitutes the rib. , and furthermore, to prevent its progress.

Here, the interval W between the narrow grooves is W-03 to 0.14.
×T is used because if the interval W is smaller than 0.03×T, the negative shear force generated in the rib defined between the pair of narrow grooves will not be sufficient, and the other ribs will This is because a negative shearing force is generated, and the other ribs are also dragged, and it is not possible to effectively prevent the occurrence of uneven wear nuclei in the other ribs, and furthermore, the progress thereof.

On the other hand, if the interval W is made larger than 0.14×T, the negative shear force generated on the rib defined by the pair of narrow grooves becomes too large, and other ribs will also be affected by it. This is because, on the contrary, the nucleus of uneven wear and its progress will be accelerated.

Then, sipes are formed spaced apart from each other in the tire circumferential direction in the area sandwiched by the narrow grooves located on the inner side in the tire width direction of each set, and the interval K between the sipes that are adjacent to each other in the tire circumferential direction is set. , K=0.05~0.50
It shall be ×A.

This not only ensures drainage through these sipes, but also cuts the water film formed on the road surface by the edges of the multiple rubber blocks defined by the sipes, increasing the so-called edge effect and contact area with the road surface. The purpose is to
If the sipe interval K is smaller than 0.05, the required drainage performance can be ensured, but the rigidity of the rubber block portion defined by the adjacent sipes becomes too small, resulting in poor handling stability on dry road surfaces. furthermore, so-called polygonal wear tends to occur during cornering.On the other hand, if the distance K is larger than 0.5, the rigidity of the rubber block portion defined by adjacent sipes becomes too high, This is because the contact area with the road surface decreases, and the steering stability performance in wet conditions deteriorates.

Of course, if necessary, one or more circumferential main grooves extending in the tire circumferential direction can be formed in the area sandwiched by the narrow grooves located on the inner side in the tire width direction of each set. In this case, the drainage performance of the negative layer can be improved.

(Embodiments) Hereinafter, preferred embodiments of the pneumatic tire of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a part of the tread pattern of a pneumatic tire 30 of the present invention. The internal structure of the tire is -
Since it has a radial structure similar to boat fishing, illustration is omitted here.

The tread 12 includes two circumferential main grooves 14 extending in the circumferential direction of the tire 30 and spaced apart from each other, and a rib portion defined by the circumferential main grooves and each tread edge. two pairs of narrow grooves 16a respectively formed in the
16b, a rib 34 defined by a rib 32 defined between the circumferential main grooves 14, and a narrow groove 16a located inward in the tire width direction of each circumferential main groove 14 and each related set; The ribs 32 and 34 are provided with sipes 36 formed at a constant interval K in the tire circumferential direction.

The narrow groove 16b located outward in the tire width direction of each set and extending in the circumferential direction has an inner wall located outward in the tire width direction.
0.10 inward in the tire width direction from the end surface of the tread 12
A distance C having a value that satisfies the range of ˜0.30×T can be appropriately selected. In addition, T is the tread 1 of the tire.
Indicates the width of 2.

In addition, the distance between each pair of narrow grooves 16a and 16b,
That is, the distance W between the corresponding inner walls of each narrow groove is W=
It can be selected within a range that satisfies the relationship 0.03 to 0.14×T.

It should be noted here that although the groove spacing d of these narrow grooves also depends on the groove depth h, when h=0.0?2×T, d=0.05~0.3Xh, Preferably, d=
It is assumed that the relationship 0.1 to 0.2Xh is satisfied.

When the tire makes contact with the ground, the opposing wall surfaces of each narrow groove come into contact with each other, suppressing the movement of the tread rubber at the end of each rib defined by the narrow grooves, and causing the edges of the rib to Occurrence of uneven wear nuclei in
Furthermore, this is because it is effective in preventing its progress.

Further, as is clear from FIG. 1(b), which is a cross-sectional view taken along line 1-I in FIG. 1(a), the surface portion of the rib 20 formed between the narrow grooves 16a and 16b is 34, and is further lower than the surface portion of the rib 35 defined by the narrow groove 16b and the tread edge. As a result, although the ribs 20 defined between the narrow grooves come into contact with the road surface like other ribs when the tire touches the ground, a relatively large negative shear force acts on the ribs 20 on the kicking side of the tire. Therefore, it is possible to prevent the tire from dragging on the edges of other ribs, thereby advantageously preventing the occurrence of uneven wear.

By the way, the two circumferential main grooves 14, the ribs 32 and 3 defined by the circumferential main grooves and the narrow grooves 16a, respectively.
4, the sipes 36 are formed obliquely with respect to the tire equatorial plane, and when the distance between the narrow grooves located on the inside in the tire width direction of each set is A, the sipes 36 are adjacent to each other in the circumferential direction. The distance K between the sipes 36 and the ribs 32 can be freely changed within the range of K=0.05 to 0.50×A.
．． 34, the rigidity of the trend rubber in each rib can be made appropriate.

By the way, the depth t of the sipe 36 is t = 0.6 to 1.0 with respect to the depth h of the narrow groove 16. It is assumed that the relationship OXh is satisfied, and the depth is equal to or shallower than the circumferential main groove 14.

Further, the angle θ of the sipe 36 with respect to the tire equatorial plane can be freely selected within a range from an angle substantially parallel to the equatorial plane to an angle substantially perpendicular to the equatorial plane, that is, within the range of θ = 0 to 90°. .

Further, in this embodiment, there are two circumferential main grooves 14, but the number is not limited to this, and in consideration of the drainage performance of the tire, it may be one, three or more. Of course it can be done.

FIG. 2 is a diagram showing another embodiment of the tire of the present invention,
In this embodiment, the ribs 32 defined by the narrow grooves 16a, 16a located on the inner side in the tire width direction of each pair are provided with a circumferential main groove that is oblique to the tire equatorial plane. The same figure (b) shows the shape of the tire blush along the sipes formed with sipes 136 at a constant interval K in the tire circumferential direction.
As is clear from the above, the distance C1 between the narrow groove 16b located outward in the tire width direction of each set and the tread end surface is
The distance W between the pair of narrow grooves 16a and 16b, the distance between adjacent sipes, etc. are made substantially the same as in the embodiment shown in FIG. Therefore, for the sake of brevity, a description thereof will be omitted here.

In this embodiment, two protrusions 38 are formed spaced apart from each other along the extending direction of the sipe 36, but the length of the sipe, that is, the length of the sipe with respect to the tire equatorial plane is One or three or more can be formed depending on the change in the angle θ, thereby making it possible to freely change the rigidity of the rubber block defined by the adjacent sipes 36 and narrow grooves 16a.

Therefore, since the tire shown in this example does not have a circumferential main groove extending in the tire circumferential direction, the wet performance is slightly lower than that of the tire shown in FIG.
The occurrence of wear nuclei at the edges of the rubber blocks of the tread along the circumferential main groove can be reduced, and the wear resistance of the tire can be improved.

Furthermore, another embodiment of the tire of the present invention is shown in FIG. This embodiment is similar to the embodiment shown in FIG. 1 described above in that the circumferential main groove 14 is provided;
And the extending direction of the sipes formed in each rib 32, 34 defined by the narrow groove 16a located inward in the tire width direction of each set is changed for each lip,
Each sipe 36 in each rib is formed to be substantially symmetrical with respect to the associated circumferential main groove 14. In order to improve the drainage performance using these sipes, in this embodiment, the sipes are formed from the middle part of the sipe formed in each rib 34 to the end of the sipe that opens into each set of narrow grooves 16a. The width is expanded almost uniformly, and the depth of the expanded portion is shallower than that of the sipe.

In addition, each sipe 36 formed on each rib has
Protrusions 38 are formed spaced apart from each other in the extending direction to increase the rigidity of the rubber block defined by the sipes 36, the circumferential main groove 14, and the narrow grooves 163 located inward in the tire width direction. This is similar to the embodiment shown in FIG.

Such a tire not only ensures good drainage performance like the tire shown in Figure 1, but also has sufficient wear resistance. Since the edge effect ensures contact between the tire surface and the road surface, the wet performance and steering stability of the tire can be improved.

In this embodiment, the sipe 36 formed in the rib 32 defined by the two circumferential main grooves 14 has a uniform width along its extending direction. , the width of the sipe from the middle part to the end of the sipe opening into one of the circumferential main grooves should be uniformly widened, and the width of the sipe formed on each rib 32, 34 should be the same width. Furthermore, other sipes are arranged at regular intervals in the tire width direction on the edge portions of the ribs 32, 34 facing the circumferential main groove 14 and the narrow groove 16a located on the inner side in the tire width direction. It is also possible to set

[Comparative Example] A comparative test regarding wet performance and leakage and wear resistance performance between the tire according to the present invention and a conventional tire will be described below.

◎The test tire size is 100OR/20 and has a general radial structure.

- Invention Tire 1 A tire having the tread pattern shown in Fig. 1, with a tread width T of 210 mtn, and a distance C between the tread edge and the narrow groove located on the outside in the tire width direction of 25 mm, each pair forming a pair. The interval W between the narrow grooves is 15 mm, the groove depth h of each narrow groove is 15 mm, the interval A between the narrow grooves located on the inside in the tire width direction of each set is 120 nan, and therefore the groove of each narrow groove. The distance d is 2.5 mm, the distance K between adjacent sipes is 10 cylinders, the size depth L is 13.5 cylinders,
A tire with a circumferential main groove width of 14 mm and a main groove depth of 15 mm.

- Inventive Tire 2 A tire having a tread pattern shown in Fig. 2, in which the tread width T is 210 mm, the distance C from the red edge to the narrow groove located on the outside in the tire width direction is 24 mm, and each pair is The interval W between the narrow grooves is 25 mm, the groove depth h of each narrow groove is 14 mm, the interval A between the narrow grooves located on the inside in the tire width direction of each set is 100 mm, and therefore the groove of each narrow groove. A tire in which the interval d is 3InIn, the interval K between adjacent sipes is 30 mm, and the sipe depth t is 12 mm.

- Inventive Tire 3 A tire having a tread pattern shown in Fig. 3, with a tread width T of 215 mm, and a distance C between the tread edge and the narrow groove located on the outside in the tire width direction of 34 mm, each pair forming a pair. The interval W between the narrow grooves is 12 mm, and the groove depth of each narrow groove is h.
is 14 mm, the interval A between the narrow grooves located on the inside in the tire width direction of each set is 110 am, therefore the groove interval d of each narrow groove is 32.5 mm, the interval K between adjacent sipes is 25 mm+, and the sipe is 14 mm. The depth L is 14ffI111
The groove width of the main groove in the circumferential direction is 12 mm, and the main groove depth is 14.5 m.
m tires.

Comparative Example 1 A tire having a tread pattern shown in FIG. 5, with a tread width T of 215111111. ) The distance from the red end to the width center of the narrow grooves formed outward in the tire width direction is 42 mm, and the interval between each pair of narrow grooves is 9 mm.
a11, a tire in which the groove depth of each narrow groove is 15.2 mm, the groove interval of the circumferential main grooves is 16.5 mm, the groove depth is 15.2 mm, and the distance between the swing width centers of the circumferential main grooves is 50 mm. .

Comparative Example 2 A tire having the tread pattern shown in Fig. 6, with a tread width T of 205 mm, a groove interval of each circumferential main groove of 13.5 mm, a groove depth of 15.2 mm, and The distance between the centers of the swing width of the circumferential main groove is 40.5 mm.
and tires.

◎Test method The above tires filled with the normal internal pressure are installed alternately on the same vehicle, and under the action of 110% normal load, a water film of 1.2 m is formed.
The vehicle was run on a road surface of 401 an/h, 601 an/h, and 801 an/h, and the wet limit performance was felt and evaluated as an index. Note that the larger the index, the better the performance.

- Leakage and wear resistance performance The above tire filled with the normal internal pressure was mounted on an actual vehicle, the normal load was applied, and the width of uneven wear that occurred after traveling 60,000 km was investigated.

◎Test Results The results of the wet performance test are shown in the following table, and the results of the scratch resistance and abrasion test are shown in Figure 4.

According to the table and FIG. 4, all of the tires of the present invention have improved wet performance compared to tires with conventional tread patterns, or have uneven wear resistance without causing a substantial decrease in wet performance. It is clear that improvements can be made.

(Effects of the Invention) Thus, according to the tire of the present invention, a pneumatic tire for heavy loads with well-balanced wet performance and wear resistance performance can be obtained, as shown in the table above and FIG. 4.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a preferred embodiment of this invention, FIG. 2 is a diagram showing another preferred embodiment of this invention, and FIG. 3 is a diagram showing still another preferred embodiment of this invention. Figure 4 is a diagram showing the relationship between the width of occurrence of uneven wear with respect to the traveling distance between the tire of the present invention shown in Figures 1 to 3 and the conventional tire. FIG. 1O130-tire 12...tread 14-
Circumferential main groove 16. 16a, 16b - narrow groove 18.
36・-Sipe 20.22.24.32.34.35- Rib 38-
・Protrusion 30 Tire ＼ Fig. 1 (a) Fig. 2 (a) z (b) (b) Fig. 3 (a) /2 (b) Fig. 5 2 (b) 6 0 /6 6 4th Figure Additional hit distance (km) 4 2 z 2 2Φ

Claims (1)

[Claims] 1. A heavy-duty pneumatic tire applied to vehicles such as trucks and buses, which comprises two sets of tires spaced apart in the tire width direction, extending in the tire circumferential direction. The tire includes at least a pair of narrow grooves spaced apart from each other, and a plurality of sipes formed at constant intervals in the tire circumferential direction between the narrow grooves located on the inside in the tire width direction of each set, and the tread width of the tire is T, and the tread width is T. The distance from the end to the narrow groove located outward in the tire width direction of each set is C, the distance between the pair of narrow grooves in each set is W, and the narrow groove located inward in the tire width direction of each set. The distance between the narrow grooves is A
, and when the distance between the sipes that are spaced apart from each other in the tire circumferential direction is C=0.10-0.30×T W=0.03-0.14×T K=0.05-0. A pneumatic tire for heavy loads, characterized by satisfying 50×A. 2. The load according to claim 1, comprising at least one main groove extending in the tire circumferential direction within a region defined by the narrow grooves located on the inner side in the tire width direction of each set. Heavy duty pneumatic tires.