JPH06316204A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To enhance the on-ice braking performance, wandering resistance, and abrasion resistance by forming the tread width, grounding width, inclination in a part outside of the tread end, and surface length with respective specific values, providing a small slope longitudinal aux. groove and a shoulder longitudinal aux. groove, furnishing in this part a plurality of cuts in the tire axial direction, and forming the belt width in a specific dimension. CONSTITUTION:The grounding width W is made approx. the same as the tread width TW, being no less than 80% of the tire max. width MW. The inclination 9 of a small slope part 12 at the tread edge E to the tire equator C is made between 40-50 deg., while the surface length made between 5-10% of the tread width TW. A shoulder region SH is provided between an outside point 0, which lies at a distance 0.015 times as large as the tread width TW to the tire equator C side from the tread edge E, and an inside point I 0.05 times as large as the tread width TW. Cuts 17..., 19... having no groove width are provided in the tire axial direction between the small slope longitudinal aux. groove 15 and shoulder longitudinal aux. groove 16 and between the same aux. groove 15 and the outer end F of the small slope part 12. The belt width BW is made between 1.0-1.04 times as large as the grounding width W.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire which can improve both braking performance on ice, wandering resistance, skid resistance and uneven wear resistance, and can be suitably used even in flat tires.

[0002]

2. Description of the Related Art Conventionally, a spike tire in which a chain is attached to a tire or a spike is driven has been used for traveling on an icy road surface or a snowy road surface. However, in recent years, because the road surface is damaged by spikes and dust is blown off by scraping the road surface, the installation of spike tires and chains using hard spikes has become self-restraining, and so-called studless tires without spikes have become popular. It's starting.

Such studless tires are inferior in running performance such as grip performance and braking performance on ice / snow road surfaces to those of the above-mentioned spike tires, and in particular, skid tends to occur when turning on ice / snow road surfaces. is there. Therefore, in heavy-duty tires used for buses, trucks, etc., in order to ensure running performance on ice and snow, the flatness is reduced to increase the ground contact area, and in order to maintain a stable ground contact, it is flat and the radius of curvature of the tread surface is large. To increase the rigidity of the tread.

[0004]

However, in the tire constructed as described above and having an oblateness of 55 to 75%, the tread surface is long in the tire axial direction and the radius of curvature of the tread surface is large. Therefore, it is not easy for the rut to come out, and the anti-wandering performance is deteriorated.

Further, it is difficult to maintain a stable ground contact surface shape, and uneven wear due to siping provided for improving grip is apt to occur.

In addition, in the conventional studless tire, as shown in FIGS. 9 and 10, a vertical sub-groove f is provided along the tread edge e to prevent side slip during turning. When a curved surface s formed of an arc is provided on the tread edge e in order to get over the rut w, the opening end of the vertical sub-groove f adjacent to the tread edge e is the starting point of uneven wear as shown in FIG. Uneven wear, which is indicated by the one-dot chain line in the figure), is promoted.

[0007] However, the braking performance on ice and the anti-wandering performance are as follows in a vehicle traveling in a snowy area or an icy area.
On the other hand, in the case of heavy-duty tires such as buses and trucks, it is essential to suppress uneven wear in order to improve durability.

In order to improve each of these performances in a well-balanced manner, the inventor has conducted research and trials on the sectional shape of the tire and the configuration of the tread groove, and as a result, regulated the ground contact area where the tread surface contacts the road surface, and The present invention has been found to be solved by limiting the shape of the buttress portion extending from the tread edge and the arrangement of the vertical sub-grooves along the tread edge, and further limiting the width of the belt layer within a certain range, respectively, to complete the present invention. It was.

The present invention can improve the braking performance on ice, wandering resistance, and uneven wear resistance even in flat tires, and is suitable for heavy vehicles such as trucks and buses running in snowy areas and icy areas. Also aims to provide a pneumatic tire that can be suitably adopted.

[0010]

According to the present invention, there is provided a carcass which passes from a tread portion through a sidewall portion and folds around a bead core of a bead portion, and a belt which is arranged inside the tread portion and outside the carcass in a radial direction of a tire. And a tire flatness of 55% or more and 75% or less, and a main groove consisting of a longitudinal groove extending in the circumferential direction on the tread surface and a lateral groove intersecting with the longitudinal groove and extending to the tread edge. A pneumatic tire having a block pattern or a rib block pattern provided, wherein a tread width that is a distance in the tire axial direction between tread edges in a normal state in which a rim is assembled to a regular rim and a regular internal pressure and a regular maximum load are applied. Is 80% or more of the maximum tire width, and in the normal state, the ground contact width, which is the length in the tire axial direction of the ground contact area where the tire contacts the road surface, is The tread has substantially the same length as the tread width, has a small slope inclined inward in the tire radial direction from the tread edge toward the outside in the tire radial direction, and extends substantially linearly to be continuous with the buttress surface. The inclination with respect to the tire equatorial plane is 40 degrees or more and 50 degrees or less, and the surface length in the tire axial direction of the small slope is 5 to 10% of the tread width,
An outer point that separates a distance of 0.015 times the tread width from the small slope portion and the tread edge toward the tire equator side;
A small slope vertical sub-groove that extends in the circumferential direction and opens in a lateral groove and is continuous or intermittent in the shoulder region between the inner edge of the tread edge that is separated by 0.05 times the tread width from the tire equatorial side. And the shoulder vertical sub-grooves are provided, and the belt width of the belt layer in the tire axial direction is 1.0 to 1.04 of the ground width of the ground area.
And a plurality of grooves that extend in the tire axial direction and have substantially no groove width between the shoulder vertical sub-groove and the small slope vertical sub-groove and between the small slope vertical sub-groove and the small slope outer end. A pneumatic tire characterized by having notches provided in a space.

[0011]

In a flat tire having an aspect ratio of 55% or more and 75% or less, the tread width in the normal state is 80% or more of the maximum tire width, and the length of the ground contact area in the tire axial direction is substantially the same as the tread width. I am long. With such a configuration, the radius of curvature of the tread surface in the tire axial direction is formed to be a large radius of about 6 times or more the tire cross-section height.

Further, the grounding width of the grounding area is substantially equal to the tread width, that is, the grounding is performed over substantially the entire tread width.
The grip power is increased and the braking ability on ice and snow roads can be improved.

Further, a small slope portion extending linearly outward from the tread edge toward the tire axial direction is formed, and the slope surface is inclined at an angle of 40 degrees or more and 55 degrees or less with respect to the tire equatorial plane. . In a conventional tire, as shown in FIG. 10, an arc having a small radius is provided in order to get over the rut. However, in the case of forming the arc, the contact position depends on the depth of the rut. Not determined, and the wandering resistance was unstable. However, by making the small slope straight, it is possible to stabilize the force for climbing the rut.

If the inclination of the small slope portion is less than 40 degrees, the camber thrust becomes small, and the climbing ability of the rudder decreases. On the other hand, if it exceeds 55 degrees, the small slope portion is repelled by the side wall surface of the rudder and it becomes impossible to climb over. Because there is a danger.

When the surface length of the small slope is less than 5% of the tread width, the small slope is small and it is difficult to get over the rudder. Is increased, resulting in higher cost.

Further, a small slope vertical sub-groove and a shoulder vertical sub-groove extending in the circumferential direction are provided in the small slope portion and the shoulder region near the tread edge, respectively. By providing such a vertical sub-groove, the tread edge is formed with an edge in the tire circumferential direction, and the vertical sub-groove enhances grip performance with respect to the acting force in the tire axial direction including the cornering force during turning, Along with the above-mentioned configuration in which the ground contact area extends to the edge of the tread, it is possible to prevent the side slip of the tire during turning. Moreover, since the vertical sub-grooves are provided on both the small slope portion and the shoulder region, the lateral slip during turning can be prevented more efficiently.

In addition, the belt width of the belt layer is formed to be 1.0 to 1.04 times the ground contact width, that is, equal to or slightly larger than the ground contact width, so that the rigidity is maintained over substantially the entire tread portion including the shoulder region. As a result of the equalization, the gripping force is stable, uneven wear can be suppressed, and in addition to being a flat tire, the wandering resistance of the tire can be further enhanced.

In addition, since a notch extending in the tire axial direction and having no groove width is provided between the shoulder vertical sub-groove, the small slope vertical sub-groove, and between the small slope vertical sub-groove and the outer end of the small slope, it is possible to prevent ruts. The grip is improved and you can get over it more easily and surely. Further, slippage between the ground contact surfaces is eliminated and uneven wear can be effectively prevented.

As described above, according to the present invention, the above-mentioned constitutions are organically and integrally formed, so that even a flat tire can have an ice dynamic braking property, a side skid resistance, a wandering resistance and a resistance to wandering. Both uneven wear resistance can be improved, and even a flat heavy-duty tire can travel safely and stably on an icy and snowy road.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, a pneumatic tire 1 includes a tread portion 2, a sidewall portion 3 extending from both ends thereof inward in the tire radial direction, and a bead portion 4 connected to an inner end of the sidewall portion 3 in the tire radial direction. Have and. Further, the pneumatic tire 1 has a body portion 6a that extends from the tread portion 2 through the sidewall portion 3 to the bead portion 4, and a turnback portion that is folded back around the bead core 5 of the bead portion 4 from the inner side to the outer side in the tire axial direction. A carcass 6 having 6b,
A belt layer 7 disposed inside the tread portion 2 and outside the carcass 6 in the radial direction.

Further, the pneumatic tire 1 has a tire height TH from the bead line BL of the tire with respect to the maximum tire width MW.
The flatness ratio, which is the ratio, is set in the range of 55% or more and 75% or less. By forming such a flat tire, it is possible to increase the ground contact area S of the tire, particularly the ground contact width which is the length in the tire axial direction, and easily improve the grip performance.

In the tread portion 2, the tread width TW, which is the distance between the tread edges E, E in the tire axial direction.
Is set to 80% or more of the maximum tire width MW.

The carcass 6 is composed of one or more carcass plies, in this embodiment two or more carcass plies, each having a carcass cord of radial or semi-radial arrangement which is inclined at an angle of 60 to 90 ° with respect to the tire equator C. Further, as the carcass cord, cords of organic fibers such as nylon, rayon, polyester and aromatic polyamide fibers are used.

The belt layer 7 comprises a plurality of belt plies, three in this embodiment, and each belt ply has an organic fiber such as nylon, rayon, polyester, aromatic polyamide fiber, or the like, like the carcass ply. Belt cords made of inorganic fibers such as steel cords are arranged at an angle of 10 to 70 ° with respect to the tire equator C, and adjacent belt cords are arranged so as to intersect with each other.

On the tread surface 2A, in the present embodiment, a central longitudinal groove 9A bent in a zigzag shape on the tire equator C, and on both sides in the tire axial direction and from the tire equator C to 0.375 times the tread width TW or less. The three vertical grooves 9B and 9B, which are arranged in the central region M of the tread portion 2 and are formed in a zigzag shape, and the vertical groove 9 on the side.
A plurality of lateral grooves 10 ... Which connect B and the tread edge E are provided.

Further, between the central and side vertical grooves 9A, 9B, the vertical small grooves 22, 22 each having a groove width smaller than those of the vertical grooves 9 and formed of straight grooves, the vertical small groove 22, and the central vertical groove. 9
Horizontal small groove 23 that connects the vertical groove 9B of A and the side,
24 are provided.

On the tread surface 2A, these vertical grooves 9, ..., Horizontal grooves 10, ..., Vertical small grooves 22, 22, and horizontal small grooves 23 ,.
A block pattern including a plurality of blocks 21 ...

In this embodiment, the vertical groove 9 and the horizontal groove 1 are used.
The groove depths GH and GH1 of 0 are 4 to the tread width TW.
In the range of 12%, the groove width GW is 6 to 6 of the tread width TW.
It is set in the range of 12%. The groove depth GH of the lateral groove 10
1 is preferably set to be equal to or slightly shallower than the groove depth GH of the vertical groove 9.

In the normal state in which the pneumatic tire 1 is assembled on the regular rim J and the regular internal pressure and the regular maximum load specified for the tire 1 are applied, the tire 1 comes into contact with the road surface in a ground contact area S. Ground contact width W, which is the axial length of the tire
Is approximately the same length as the tread width TW. That is, in the normal state, the tread width TW is grounded over substantially the entire area.

In the ground area S, the land ratio, which is the ratio of the total area of the blocks 21 to the total area of the ground area S, is preferably 60% or more. This is because if the land ratio is less than 60%, the ground contact pressure acting on the surface of the block 21 becomes large and wear is prematurely reduced to reduce the durability.

The tread portion 2 is formed with a small slope portion 12 having a small length which inclines inward in the tire radial direction from the tread edge E outward in the tire axial direction, and the outer end of the small slope portion 12 is formed. F is connected to the buttress surface 13 of the sidewall portion 3. Further, in order to easily ride over the inclination θ of the small slope 12 with respect to the tire equatorial plane C, the surface length L in the tire axial direction along the surface of the small slope is 40 degrees or more and 50 degrees or less and the surface length L in the tire axial direction is set to the tread width. The range is 5 to 10% of TW.

On the tread surface 2A, a tread edge E
The outer point O that separates the tread width TW by 0.015 times on the tire equator C side and the tread edge E that separates the tread width TW by 0.135 times on the tire equator C side. Shoulder area S between inner point I
Set H.

The small slope portion 12 is provided with small slope vertical sub-grooves 15 extending in the tire circumferential direction and opening at the lateral grooves 10 and 10 on both sides of the block 21, and shoulder vertical sub-grooves 16 are provided in the shoulder region SH. To be

Small slope vertical sub-groove 15, shoulder vertical sub-groove 16
Extend continuously in a direction parallel to the equatorial plane of the tire, and in this embodiment, as shown in FIG. 4, the central portion of the groove and the opening ends on the both sides are formed to have substantially the same depth and are formed as grooves of substantially uniform depth. ing.

The maximum groove depth gm of each of the vertical sub-grooves 15 and 16 is preferably 0.4 times or more and 0.8 times or less the groove depth GH of the lateral groove 10.

The groove width gw of each of the vertical sub-grooves 15 and 16 is preferably in the range of 1 to 3 mm. If the groove width gw is less than 1 mm, when force is applied in the tire axial direction during turning,
If the groove walls on both sides come into contact with each other, side slippage is likely to occur, and if it exceeds 3 mm, stone trapping is likely to occur and the tread edge may be damaged.

The small slope sub-groove 15 and the shoulder vertical sub-groove 16 may be formed by inclining the groove direction at an angle α with the tire equatorial plane C, as shown in FIG. The groove depth gh is regulated by the depth in the direction parallel to the tire equatorial plane C.

Further, the shoulder vertical sub-groove 16 and the small slope vertical sub-groove 1
5, and between each of the small slope vertical sub-grooves 15 and the outer end F of the small slope portion 12, a plurality of notches 17 extending in the tire axial direction and having no groove width are formed. It is provided.

Incidentally, straight or zigzag-shaped sipings 25 extending in the tire axial direction are appropriately provided on the block 21 to enhance the gripping force, especially the braking performance on a snowy and snowy road surface.

In the belt layer 7, the belt width BW, which is the length in the tire axial direction, is set to the ground contact width W of the ground contact area S.
The range is 1.0 to 1.04 times, and the ground width W is made equal to or slightly larger than the ground contact width W. As a result, the belt layer 7 is reinforced over the entire area of the tread portion 2, the rigidity of the tread portion 2 is made uniform, and uneven wear in the shoulder region SH can be further suppressed.

FIGS. 6 and 7 show another mode in which the groove depths of the vertical sub-grooves 15 and 16 are different between the opening end and the central portion.

In FIG. 6, the groove bottom is deep in the central part, and shallow groove parts are provided on both sides of the groove bottom to form a two-step deep groove connecting the two with a stepped part, and the groove depth is formed in the central part. g
m is set to a maximum groove depth of 0.4 to 0.8 times the groove depth GH1 of the lateral groove 10, while both side portions have 0.25 to 0 of the groove depth gm of the central portion at their opening ends. It is formed to have a groove depth ge of 5 times. Note that, as shown in FIG. 7, the groove bottom in the central portion can be formed in an arc shape with the maximum groove depth gm at the intermediate position.

This is because in the vertical sub-grooves 15 and 16, the tread rubber is easier to move at the opening end than at the central portion, so that uneven wear starting from the opening end as shown in FIG. 11 occurs. 6 and 7, as shown in FIGS. 6 and 7, the vertical sub-grooves 15 and 16 are made shallow in the vicinity of the opening end to suppress the movement of the tread rubber, and the vertical sub-groove 1
It is possible to further suppress the occurrence of uneven wear that tends to occur in the vicinity of the open ends of 5 and 16.

Further, FIG. 8 shows that two shoulder vertical sub-grooves 16A and 16B are provided in the shoulder region SH, and the shoulder vertical sub-groove 16B on the side close to the tread edge E is formed therein.
At, a small discontinuity portion 26 is provided in the central portion.
Such a discontinuity 26 is effective when the shoulder vertical sub-groove 16 is provided in the shoulder region SH, which causes an extreme decrease in rigidity. Such a discontinuity can also be provided in the small slope vertical sub-groove 15.

[0045]

[Examples] Tires having a tire size of 195 / 70R17.5 and having the configuration shown in FIG. 1 (Examples 1 to 4)
Was manufactured under the basic conditions shown in Table 1 according to the specifications shown in Table 2 and its performance was tested. For comparison, a tire having a conventional structure (Comparative Example 8) and a tire having a structure other than the structure of the present application (Comparative Examples 1 to 7) were also tested to compare their performances.

[0046]

[Table 1]

[0047]

[Table 2]

The test conditions are as follows. 1) Camber thrust A test tire was mounted on a rim of 17.5 × 6.00, an internal pressure of 6.0 kg / cm ² was applied, and a load of 1000 kg per tire was measured using a 60-inch drum tester.
Under the conditions, the measurement was performed at a speed of 10 km / H and a camber angle of 6 °. The larger the value is, the more excellent the skid resistance is.

2) Anti-Wandering Performance A test tire was mounted on the front wheels of a 2-D type 2-ton truck, and a rustic test course was run for 80 to 90 km.
Driving with 5 test drivers such as going straight in the rut at the speed of / H, entering the rut, exiting and intentionally hitting the tire's wall, etc., and evaluated by the feeling of each driver The average value of is shown as an index with Comparative Example 8 as 100. The larger the value, the better.

3) Braking performance on ice 60 degrees on a test road surface formed on an ice board with an outside air temperature of -5 ° C.
While traveling at a speed of km / H, measure the braking distance until the car stops by suddenly braking with 4 wheel lock,
The reciprocal value of the distance was shown as an index with Comparative Example 8 being 100. The larger the value, the better.

4) Uneven wear resistance A test tire was mounted on the front wheels of an actual vehicle under the same conditions as in 2), and the normal road surface was left / right-shifted every 20,000 km, and the front / rear sides of blocks with vertical sub-grooves The uneven wear amounts m ₁ and m ₂ (shown in FIG. 11) are measured in step 1, the average value M = (m ₁ + m ₂ ) / 2 is calculated, and each of the four blocks is divided into four equal parts on the circumference. The uneven wear amount was averaged to obtain the uneven wear of the tire. The numerical values shown in Table 3 are 100 in Comparative Example 8.
The smaller the value, the smaller the uneven wear amount.

5) Durability After the test of the item 4), the presence or absence of cracks in the tread surface, especially in the vicinity of the vertical sub-grooves and the peeling of the belt edge was examined, and the index was set as 100 in Comparative Example 8. The larger the value, the better. The test results are shown in Table 3.

[0053]

[Table 3]

As a result of the test, it was confirmed that the camber thrust, the wandering performance, the braking performance on ice, the wear resistance and the durability of the example were improved in a well-balanced manner as compared with the comparative example.

[0055]

As described above, the pneumatic tire of the present invention is
A small slope that inclines at a regulated angle with respect to the tire equatorial plane is formed outside the tread edge, so it has excellent wandering resistance and a small slope vertical extension that extends in the circumferential direction near this small slope and the tread edge. Since the groove and the shoulder vertical sub-groove are formed and have substantially the same length as the belt width and the ground contact width, it is possible to enhance the cornering force and prevent side slip during turning, particularly during turning on ice and snow roads.

As described above, according to the present invention, regardless of the flat tire, it is possible to eliminate the deterioration of the wandering resistance and the uneven wear resistance, which have been the drawbacks of the flat tire in the related art, and the studless tire traveling on the snowy and snowy road surface. Can be suitably adopted as.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a developed plan view illustrating the tread pattern.

FIG. 3 is an enlarged perspective view showing a shoulder region of the tread portion.

FIG. 4 is a circumferential sectional view of the vertical sub-groove.

FIG. 5 is a tire axial direction sectional view showing another example of the vertical sub-groove.

FIG. 6 is a sectional view in the circumferential direction showing another example of the vertical sub-groove.

FIG. 7 is a sectional view in the circumferential direction showing another example of the vertical sub-groove.

FIG. 8 is a partial perspective view showing another example of the vertical sub-groove.

FIG. 9 is a cross-sectional view showing a conventional tire.

FIG. 10 is a cross-sectional view schematically showing the rudder riding state.

FIG. 11 is a perspective view schematically showing the occurrence of uneven wear.

[Explanation of symbols]

 2 tread portion 2A tread surface 3 sidewall portion 4 bead portion 5 bead core 6 carcass 7 belt layer 9 vertical groove 10 horizontal groove 11 main groove 12 small slope portion 13 buttress surface 15 small slope vertical auxiliary groove 16 shoulder vertical auxiliary groove 17, 17 cut BW Belt width C Tire equator E Tread edge F Outer edge of small slope GH Groove depth of main groove GH1 Groove depth of lateral groove gm Maximum groove depth of vertical auxiliary groove gw Groove width I Inner point J Regular rim MW Tire maximum Width O Outside point S Grounding area SH Shoulder area TW Tread width W Grounding width

[Table 2]

[Table 2]

Claims (3)

[Claims] 1. A tire comprising: a carcass that folds back from a tread portion through a sidewall portion and around a bead core of a bead portion; and a belt layer disposed inside the tread portion and outside the carcass in a radial direction of the tire. Flatness of 55% or more and 75% or less, and a block pattern or rib block pattern provided with a main groove composed of a longitudinal groove extending in the circumferential direction on the tread surface and a lateral groove intersecting with the longitudinal groove and extending to the tread edge. In a pneumatic tire of, the tread width, which is the axial distance between the tread edges, is 80% or more of the tire maximum width in a normal state in which the rim is assembled to the regular rim and the regular internal pressure and the regular maximum load are applied. Moreover, in the normal state, the ground contact width, which is the length in the tire axial direction of the ground contact area where the tire contacts the road surface, is substantially the same as the tread width. A small slope that slopes inward in the tire radial direction from the tread edge outward in the tire axial direction and that extends in a substantially straight line and is continuous with the buttress surface, and the slope of the small slope with respect to the tire equatorial plane is 40. The surface length in the tire axial direction of the small slope is 5% to 10% of the tread width.
And an outer point that separates a distance of 0.015 times the tread width from the small slope portion and the tread edge toward the tire equator side,
A small slope vertical sub-groove that extends in the circumferential direction and opens in a lateral groove and is continuous or intermittent in the shoulder region between the inner edge of the tread edge that is separated by 0.05 times the tread width from the tire equatorial side. And the shoulder vertical sub-grooves, and the belt layer has a belt width, which is a length in the tire axial direction, of 1.0 to 1.04 times the ground contact width of the ground contact area, and A plurality of cuts extending in the tire axial direction and having substantially no groove width are provided between the small slope vertical sub-groove and between the small slope vertical sub-groove and the outer end of the small slope. Pneumatic tires. 2. The small slope vertical sub-groove and the shoulder vertical sub-groove each have a groove width of 1 to 3 mm, and the maximum groove depth in a direction parallel to the tire equatorial plane of each vertical sub-groove is the groove depth of the lateral groove. Is 0.4 times or more and 0.8 times or less, and the opening end groove depth at the opening end of each vertical sub-groove is 0.25 times or more the maximum groove depth of each vertical sub-groove and 0. The pneumatic tire according to claim 1, wherein the pneumatic tire is 5 times or less. 3. The pneumatic container according to claim 1, wherein the small-slope vertical sub-groove and the shoulder vertical sub-groove have a groove depth that decreases from the central portion toward the opening end. tire.