JPH03186408A - Tire for use in heavy load - Google Patents

Abstract

PURPOSE:To improve side slip resistance and braking performance on an ice- snow road together with improved durability having uneven wearing decreased by arranging a fine groove and siping, with the respective depths specified, in a side part block in the tread part of a tire. CONSTITUTION:A main groove G, comprising a plurality of longitudinal grooves GR extended in a peripheral direction C and a plurality of lateral grooves GL crossed with respect to the peripheral direction, is arranged thus to form a tread pattern, contained with a side part block 3, in a tread part 2 of a tire. A fine groove 4, extended in the tire peripheral direction, and a siping 5, opened to an opening 4 of the fine groove 4, are arranged in the side part block 3. In the fine groove 4, its width Wb and depth HB are set respectively to 1.5mm to 4.0mm and 0.35 or more times the depth HA of the main groove G. On the other hand, in the siping 5, its depth Hc on the side of the tire equator is set larger as compared with the depth Hs on the side of the fine groove, while a mean depth Hm of the siping 5 is set to 0.35 or more times the depth HA of the main groove G.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a heavy-duty tire that can increase resistance to uneven wear on general roads, and improve structural slippage resistance on icy and snowy roads and braking performance on water. Regarding.

[Conventional technology]

Large vehicles such as trucks and buses often travel on icy and snowy roads in winter and during snowfall, in addition to traveling on -a roads.

When driving on such icy and snowy roads, spiked tires have conventionally been used in which chains are attached to tires or spikes are driven into the tires. However, in recent years, due to road surface damage and dust pollution caused by chains and spikes, people are refraining from installing spiked tires and chains with hard spikes, and so-called spikeless tires without spikes are being used. .

Conventionally, such spikeless tires have improved on-ice performance by forming a block pattern on the trend surface using blocks, and by arranging multiple lateral grooves or multiple sipes in the axial direction of the tire. I came.

[Invention tries to solve it! J, u'3 However, with the tire having the above configuration, when running on a general road surface, so-called heel-and-toe wear occurs, in which gi4 wear occurs at the running direction 2 and the end of the block, and when running on an icy and snowy surface, Performance on ice was poor, and skids tended to occur when turning on ice and snow.

The uneven wear can be alleviated by providing a large number of thin cuts on the side edges of the tread, but when driving on icy and snowy surfaces, the rubber in the tread becomes cold and its hardness decreases. At this point, the tear resistance also decreases. Therefore, in order to ensure tear resistance, if the cut is extended to the edge of the tread, the shear force that scrapes the compacted snow surface will decrease near the edge, resulting in poor race grip and side slipping during turns. The problem of preventing this and improving braking performance on ice has not been completely solved.

The present invention is based on providing side blocks with narrow grooves that extend in the tire circumferential direction apart from the tread edge, and sipes that open at the narrow grooves, thereby increasing resistance to uneven wear on general roads and improving durability. The objective is to provide a heavy-duty tire that can improve safety by improving structural slippage resistance on icy and snowy roads and braking performance on ice.

(Means for Solving the 81 Problems) The present invention provides a tread section of a tire with a leading edge consisting of a plurality of vertical grooves extending in the circumferential direction and a plurality of lateral grooves extending in a direction crossing the circumferential direction. By providing a block pattern including side blocks spaced apart along an edge of the tread portion, the side blocks include:
a narrow groove extending in the circumferential direction of the tire at a distance of 0.4 times or less of the maximum weight of the side block in the tire axial direction from the edge; A plurality of sipes extending toward the edge of the side block are provided, and the narrow groove (HB) has a groove width of 1.5 fi or more and 4. Otm or less, the groove depth is the groove depth of the main groove (H
A) 0.35 times or more (HA
) is 0.35 times or more and 5 is a heavy-duty tire.

[Function] Since the narrow groove is arranged at a distance of 0.4 times or less of the maximum weight of the side block starting from the edge of IIa, the braking performance on ice and the structural slip resistance in the ice and snow furnace are improved. Furthermore, by making the depth of the narrow grooves in the HB grooves 0.35 times or more than the depth of the main grooves in the HA, it is possible to further improve the stability of the structure on icy and snowy roads.

Furthermore, by making the siping larger on the tire equator side than on the narrow groove side, it is possible to reduce the amount of uneven wear on the heel and toe.

Furthermore, the average groove depth HMS of the siping is changed to the groove depth H of the upper groove.
By setting A to 0.35 times or more, braking performance on icy and snowy surfaces can be improved.

As described above, in the present invention, by organically bonding the bottom of the tank, on-ice performance such as on-ice braking performance and braking resistance is improved, and the tire according to the present invention can be used in all weather conditions.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

As shown in FIGS. 1 to 3, the heavy-duty tire 1 of the present invention has a plurality of longitudinal @GR...
. . . and a plurality of lateral grooves GL extending in a direction intersecting the circumferential direction. forming a tread pattern including side blocks 3,
The side block 3 is provided with a narrow a4 extending in the tire circumferential direction and a siping 5 opening at the narrow groove 4.

In this embodiment, the vertical grooves GR and the horizontal grooves GL are formed so that the groove depth is equal to that between the grooves. The heavy-duty tire 1 also has a sidewall portion 13.13 extending inward in the tire radial direction from both ends of the trend portion 2, and a bead portion 15.15 located at the radially inner end of the sidewall portion 13. ,1
A toroidal carcass 17 passing through the sidewall portion 13, 13 and the tread portion 2 is placed between the two, and a belt layer 19 is arranged on the outside in the radial direction and within the tread portion 2.

The carcass 17 has a carcass cord connected to the equator C of the tire.
On the other hand, in this embodiment, it is a so-called radial or semi-radial direction arrangement body arranged at an angle of 30 degrees to 90 degrees,
In addition to steel cords, fiber cords such as nylon, polyester, rayon, and aromatic polyamide are used as carcass cords.

In this embodiment, the heald layer 19 has two belt plies arranged from the carcass 17 side toward the outside in the radial direction of the tire.

The belt layer 19 also includes belt cords that are arranged at an angle to each heltbray and intersect with each other, and the belt cords 1 and the belt cords 19 are made of steel cords, nylon, polyester, rayon, aromatic boria, etc., similarly to the carcass 17. fiber cord is used.

In this embodiment, the side block 3 has a block edge 6 on the edge E side located above the edge E, and a block edge 7 on the equator side facing toward the equator C in the evening.

The narrow groove 4 is arranged in the tire circumferential direction at a distance of 0.4 times or less of the maximum weight Wm in the tire axial direction between the block edge 6 on the edge side and the block edge 7 on the equator side from the edge E. Grow.

The distance from the edge E is 0.0 of the maximum weight Wm of the side block 3.
When it exceeds 4 times, as shown in the graph of FIG. 4, not only the braking performance on ice but also the structural slip resistance deteriorates significantly.

Also, the narrow groove 4 mainly has its a depth HB? JIG groove depth HA
0.35 times or more. 6th if less than 0.35 times
As shown in the graph in the figure, the structural slip resistance is significantly reduced. In addition! The groove width wb of J4 is preferably 2 m or more and Ion or less.

The siping 5 extends in the axial direction of the tire, and one end is the thin A4
The other end extends to the block edge 7 facing the tire red iIC in this embodiment.

In addition, the siping 5 has a depth Hc on the tire red iIC side that is larger than the groove depth Hs on the narrow groove 4 side, and in this embodiment,
The groove bottoms of the sipes 5 have an inclined part in the middle and are smoothly connected.

Moreover, the average groove depth Hm over the entire length of the siping 5 is set to be 0.35 times or more the groove depth HA of the main groove G. 0.
If it is less than 35 times, the braking performance on ice deteriorates as shown in the graph of FIG.

On the other hand, if the average a depth Hm of the sipes 5 becomes large, the rigidity of the side block 3 will decrease and there is a risk of uneven wear. It is preferable to set it to 0.75 times or less.

Further, it is preferable that the siping 5 is cut into the raw cover tire after vulcanizing it using a cutter or the like, so that the groove width thereof is substantially zero. By setting the groove width to 0 in this way, the lateral edge components of both edges of the sipe 5 are pressed together so as to sink into the icy road due to the compressive stress acting within the ground contact surface, thereby improving running performance on the icy and snowy road.

〔Concrete example〕

It has the configuration shown in FIG. 1 and FIG.
A prototype R22.5 tire was manufactured and its performance was tested. Also, for comparison, here is a book! Tires outside the scope of the I configuration were also prototyped and tested.

Each test was conducted under the following conditions.

l) Braking performance on ice When installed on an actual vehicle, the test road surface formed by a water basin was
The vehicle was driven at a speed of 0 km/h, the four wheels were locked, and the brakes were applied suddenly, the braking distance until the vehicle came to a stop was measured, and the reciprocal of that distance was expressed as an index.

2) Structural resistance The vehicle was run under the same conditions as in section 1), and the distance over which the vehicle skidded when turning sharply was measured.

3) Resistance to uneven wear The front was fixed, and after driving on a paved road for 1,000 days, the amount of heel and toe, which is the difference in wear between the block pieces before and after the siving, was measured.

Figure 4 shows the ratio of the maximum weight Wm of the side block to the distance 11Wn from the edge of the narrow groove, the ice braking ability A versus W n / W m, and the ratio W n / W rn versus structural slip resistance B. It is a graph showing each relationship.

During the test, the groove width of the narrow groove was 3.0 m, and the ratio of the siping groove depth Hm to the leading groove depth HA, Hm / HA, was 0.
．． 5. Groove depth ratio H between the aa side of the siping and the tire equator side
c/Hs is 1.3 and the groove depth ratio of the leading and narrow grooves is HB/
Each was kept constant at HA=0.5. The numerical value is expressed as an index with 100 representing no grooves, and the larger the numerical value, the better the quality.

FIG. 5 is a graph showing the relationship between the structural slip resistance and the groove depth ratio HB/HA between the main groove and the narrow groove.

In addition, during the test, the position of the narrow groove 4 shown in FIG.
It is expressed as an index in which W m is set to a constant value of 0.2 and 100 indicates that no narrow grooves are provided. The larger the value, the better.

As a result of the test, it was found that when HB/HA is 0.35 or more, the sideslip property is significantly improved.

FIG. 6 is a graph showing the relationship between the groove depth ratio HC/ )l s of the narrow groove side of the siping and the tire equator side and the amount of heel and toe. It has been found that by increasing the groove depth Hc on the tire equator side compared to the groove depth Hs of the narrow groove example, the amount of heel and toe is significantly reduced.

Figure 7 is a graph showing the tendency of on-ice braking performance with respect to changes in the ratio Hm/HA of the average groove depth Hm of the siping to the groove depth HA of the main groove. It is expressed as an index of 100. Said ratio H
A m/HA of 0.35 or more indicates that the braking performance on ice is significantly improved.

〔Effect of the invention〕

As mentioned above, the main feature of the heavy-duty tire of the present invention is that the side blocks are provided with narrow grooves and sipes with respective groove depths regulated, thereby reducing uneven wear such as heel-and-toe and improving durability. At the same time, it can improve the stability on icy roads, the braking performance on ice, and the performance on ice.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a developed plan view showing the tread pattern, FIG. 3 is a sectional view showing an enlarged side block, and FIGS. It is a graph showing performance test results. 2... Tread portion, 3... Side block, 4...
Narrow groove, 5... Siping, 7... Block on the equator side, C... Tire equator, E... Edge, G... Main groove,
GR...Vertical groove, GL...Horizontal groove, HA...Groove depth of main groove, HB...Groove depth of narrow groove, Hm...Average groove depth of siping, wb... Maximum weight of side blocks.

Claims (1)

[Claims] 1 By providing the tread of a tire with a main groove consisting of a plurality of vertical grooves extending in the circumferential direction and a plurality of lateral grooves extending in a direction crossing the circumferential direction, the main groove is formed along the edge of the tread. A block pattern including spaced apart side blocks is formed, and the side blocks are spaced apart from the edge by a distance of 0.4 times or less of the maximum width of the side blocks in the tire axial direction. A thin groove extending in the circumferential direction,
A plurality of sipes opening in the narrow groove and extending toward the block edge on the tire equator side of the side block are provided, and the narrow groove has a groove width of 1.5 mm or more and 4.0 m.
m or less, the groove addition (HB) is the groove depth (HA) of the main groove
In addition, the groove depth of the siping is larger on the tire equator side than on the narrow groove side, and the average groove depth (Hm) is 0.35 times the groove depth (HA) of the main groove. .3
A tire for heavy loads that is 5 times or more heavier.