JPS63134312A - Pneumatic radial tire for heavy load - Google Patents

Abstract

PURPOSE:To improve the eccentric abrasion resistance and wet durability by forming a main groove in rectilinear form in the peripheral direction of a tire and forming the cut parts in the peripheral direction rib divided by the main groove and arranging sipes in an oil groove for connecting the cut parts. CONSTITUTION:A plurality of ribs 20 in the peripheral direction are formed in division onto a tread by at least three main grooves 10 extending perpendicular to the peripheral direction of a tire. A number of cut parts 21 each of which extends in the rib 20 in the lateral direction and has the equal depth to the main groove 10 are formed. A shallow oil groove 30 for connecting the cut parts 21 is formed in the second rib 20 from a shoulder rib 20s. Further, a peripheral direction part 32 extending at a shallow angle for the peripheral direction of the tire at the center part of the rib 20a is formed in the oil groove 30, and sipes 50 are arranged within the range of 20-40% of the rib width C on the groove bottom 31 at the center part of the oil groove 30.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heavy-duty pneumatic radial tire, and more particularly, to a heavy-duty pneumatic tire suitable for high-speed driving on good roads, whose tread pattern is a rib pattern. This invention relates to improvement of uneven wear resistance and wet resistance.

[Conventional technology]

Tires that have conventionally adopted a rib pattern as a tread pattern are suitable for running at high speeds on good roads, and good uneven wear resistance and wet resistance are important performance requirements.

However, the techniques for improving uneven wear resistance and wet resistance are contradictory techniques, and countermeasures have been taken as in conventional methods. In other words, (1) In order to achieve both the two performances of uneven wear resistance and wet resistance,
Zigzag-shaped main grooves improve traction and drainage on wet roads, while shallow lateral grooves are placed within the ribs to ensure traction and braking performance.

(2) In addition, in order to improve wet resistance, the hot water grooves provided in the ribs are deepened, and deep sipes are provided that connect the main grooves.

[Problem that the invention seeks to solve]

However, with the above-mentioned method (1), as the tread of the tire wears out, the tread groove disappears and the traction and braking performance are inevitably reduced, while the amplitude of the zigzag in the main groove is increased to improve the traction. If you try to do so, uneven wear called bar wear is likely to occur, and the resistance to uneven wear also decreases.

In addition, the method (2) currently has problems, such as uneven wear called heel-and-toe wear being more likely to occur, and resistance to uneven wear decreasing and being insufficient.

By the way, the above-mentioned heel-and-toe wear refers to the amount of wear compared to the amount of wear on the block on the stepping side that touches the ground first when the tire rolls on the road surface, among the blocks formed by grooves or sipes that cross the ribs. As a result, the amount of wear on the so-called kick-out block that later touches the ground increases, resulting in a wear level difference before and after the groove or sipe. This uneven wear is called heel-and-toe wear.

In addition, the above-mentioned river wear wear refers to the convex parts of the circumferential ribs divided by the zigzag-shaped main grooves arranged in the circumferential direction of the tire, which wear out compared to the concave parts, and as a result, a wavy pattern appears along the ribs. Wear will occur. This uneven wear is called riverwear wear.

The present invention was achieved as a result of experiments and studies in order to solve the above-mentioned problems.

Therefore, an object of the present invention is to significantly improve uneven wear resistance by suppressing the early occurrence and growth of uneven wear such as heel-and-toe wear and river wear wear, and to obtain good wet resistance. Our objective is to provide inspection of heavy duty pneumatic tires.

[Means for solving problems]

In order to achieve the above object, the present invention has a plurality of circumferential ribs partitioned by a plurality of main grooves extending substantially linearly in the circumferential direction of a tire, and a main groove on both sides of the at least one circumferential rib. Forming a number of notches extending laterally from the groove and having the same depth as the main groove, connecting the opposing notches with a groove that is shallower and narrower than the main groove, and further,
The rib width C
It is characterized in that the sipes in the hot water gutter are arranged along the hot water gutter within a range of 20 to 40% of the water gutter.

Furthermore, the hot water groove is characterized in that it has a circumferential portion extending at a shallow angle in the circumferential direction at a central portion of the rib.

[Effect]

Since the main groove is formed in a substantially linear shape in the circumferential direction of the tire, it is possible to improve drainage performance and braking performance, while suppressing the occurrence of uneven wear called river wear wear. I can do it.

Further, since a large number of notches are formed in at least one of the plurality of circumferential ribs partitioned by the main groove, and extend laterally from the main groove on both sides thereof, and have a depth equivalent to that of the main groove, the durability is improved. Good traction properties can be maintained without reducing uneven wear properties.

Furthermore, while the above-mentioned notch is connected by a gutter that is shallower and narrower than the main groove, a sipe in the gutter is positioned at the center of the gutter and placed at the bottom of the gutter within a range of 20 to 40% of the width of the rib. By arranging it along the molten metal groove, it is possible to maintain the traction and braking performance at the initial stage of wear, not only when new, but also after the molten metal groove has worn out, and also to prevent the deterioration of uneven wear resistance. I can do it.

That is, even after the grooves disappear as the tire wears, the sipes are added to the bottom of the grooves, making it possible to maintain traction performance and braking performance, and also prevent a decrease in uneven wear resistance.

Moreover, it is preferable that the above-mentioned hot water groove forms a circumferential portion extending at a shallow angle in the circumferential direction at the center portion of the rib.

This is to ensure good wet performance during cornering when driving on a wet road surface.

In other words, by arranging a circumferential portion extending at a shallow angle in the circumferential direction at the center of the rib, the rib rigidity at the center of the rib is weakened in a well-balanced manner, improving the mobility of the rib, improving drainage, and increasing the This allows for improved ground contact.

In addition, it is preferable to arrange the gutter in the circumferential direction instead of arranging it straight across the ribs, since the kicking part is dispersed and the early occurrence and growth of heel-and-toe wear can be suppressed. . Moreover, since the groove depth of the molten metal groove is formed to be shallow, early occurrence of heel and toe wear can be suppressed.

In addition, as mentioned above, the groove disappears as the vehicle runs, so when using sipes in the groove as necessary to maintain wet performance, especially traction properties, until the end of wear, it is preferable to place them on the bottom of the groove. By arranging the sipes in the groove in the circumferential direction of the central part of the rib, where heel and toe wear is less likely to occur, the problem of early heel and toe wear at the early stages of wear has been solved.

Furthermore, by inserting the sipes in the gutter along the center of the gutter, the effect of ensuring good wet performance during cornering when driving on a wet road can be further enhanced in the early stages of wear. When the sipe groove disappears, the above effect is produced in place of the sipe groove, and by increasing the circumferential portion, it is possible to effectively use the sipe, which is naturally prone to heel-and-toe wear.

〔Example〕

Hereinafter, the present invention will be specifically described by way of examples with reference to the drawings.

1 to 3 respectively show heavy-duty pneumatic radial tires according to embodiments of the present invention. FIG. 1 is a tread development view showing the main parts of the first embodiment, and FIG. −
(2) Explanatory cross-sectional view in the direction of arrows FIG. 3 is a developed view of the tread showing the main parts of the second embodiment.

The first and second embodiments shown in Figures 1 to 3 are of size TB.
R100OOR2014PI? This is an example in which the present invention is applied to a heavy-duty pneumatic radial tire having a rib pattern.

The heavy-duty pneumatic radial tire consisting of each example is as follows:
A plurality of circumferential ribs 20 are defined in the tread by at least three main grooves 10 extending substantially linearly in the circumferential direction of the tire, and ribs 20 are laterally formed from the main grooves 10 to the sides of the ribs 20.
A large number of notches 2 having a depth equivalent to that of the main groove 10 extending inward.
1, and there is a notch 21 to a notch 21 in the second rib 20n counting from the shoulder rib 20s on the shoulder side.
are connected by a shallow and narrow groove 30, and the groove 30 has a circumferential portion 32 extending at a shallow angle with respect to the circumferential direction of the tire at the center of the rib 2On. Sipe 40 is placed within the range of 20 to 40% of the rib width C to the groove 30.
The remaining ribs 20 are continuous in the circumferential direction or have a pigtail pattern in a heavy-load pneumatic radial tire, and the continuity of the remaining ribs 20 in the circumferential direction is achieved by arranging sipes 50 of short length. not be harmed by doing so.

To further explain this structure, in each of the examples,
Four linear main grooves 10 connected in the circumferential direction on the tire tread
is located.

Therefore, the rib 20 partitioned and formed by these four linear main grooves 10 is divided by the two left and right center side main grooves 10.
One center rib 20c1 formed between the above 2
Two left and right intermediate ribs 20n formed between the book's center side main groove 10c and both left and right shoulder side main grooves 10s.
, and two left and right shoulder ribs 20s formed on the tread end sides of the left and right shoulder main grooves 10s, that is, on the left and right shoulder sides.

Moreover, in each of the ribs 20 described above, a large number of notches 21 are formed at intervals of 10-10 mm, extending laterally from the main groove 10 on both sides thereof and having a depth equivalent to the depth H of the main groove 10. ing.

Note that the width A of the notch 21 is defined as 1 of the rib 20 and 1 of C of the rib 20.
It is preferable to set it within the range of 0 to 20% in order to maintain good traction properties and prevent a decrease in uneven wear resistance.

Furthermore, each notch 21 described above in the actual embodiment is
As illustrated, the opposing notches 21 are arranged in a staggered manner.

In the actual embodiment, the two left and right intermediate ribs 2On are provided with opposing notches 21 in the main groove 1, as shown in the figure.
They are connected by a hot water groove 30 that is shallower and narrower than 0, and furthermore,
A sipe 40 in the trough 30 is disposed at the center of the trough 30 and has a width S in the range of 20 to 40% of the width C of the rib 20 along the trough 30. It is made up of.

Note that while the width B of the molten metal groove 30 is set within a range of 5 to 15% of the rib width C, the depth of the molten metal groove 30 is set within a range of 5 to 15% of the rib width C.

By setting the depth H within the range of 10 to 20% of the depth H of the main groove 10, it is possible to maintain good traction properties and braking properties, and also to prevent a decrease in uneven wear resistance.

In addition, the circumferential length of the sipe 40 in the hot water groove is medium S in the lateral direction.
The depth is 1.5 to 2.5 times the depth of the hot water groove 30. By setting the depth h2 plus the main groove 10 within the range of 70 to 90% of the depth (), it is possible to suppress the occurrence of heel-and-toe wear and prevent wear without reducing uneven wear resistance. Good wet performance can be maintained until the final stage.

The angle of inclination of the sipe 40 in the groove with respect to the tire circumferential direction is most preferably 0°, but by setting it to a shallow angle of 30° at most, the occurrence of heel end toe wear can be satisfactorily suppressed. Therefore, the inclination angle of the gutter 30, in which the gutter sipes 40 are provided, with respect to the tire circumferential direction is O.

is optimal, but a shallow angle of 30° or less is desirable.

On the other hand, in order to obtain traction performance in the tire circumferential direction by the sipes 40 in the treadway, it is also possible to provide portions extending in the axial direction of the tire on both sides of the sipes 40 in the treadway, as shown in the drawings.

This axial component provides the traction performance necessary for braking, etc.
The circumferential component provides traction performance necessary for anti-skid, etc.

Further, in the first embodiment, as shown in FIG. 1, in the above-mentioned hot water groove 30, the notches 21, which are arranged in a staggered manner facing each other, are selected so that the hot water groove 30 is oriented upward to the right. It is connected.

In addition, in the second embodiment, as shown in FIG.
Select and connect so that 0 is downward to the right.

Further, in the actual embodiment, each of the troughs 30 is provided with a circumferential portion 32 extending at a shallow angle in the circumferential direction at the center of the left and right intermediate ribs 2On.

Further, in the actual embodiment, four main grooves 10 are arranged as described above, but it is sufficient if at least three or more main grooves are arranged.

In the figure, 50 is a short sipe, which is arranged at a predetermined interval on the main groove 10 side of each rib 20 as shown. By arranging such sipes 50 on the rib 20, the continuity of the rib 20 in the circumferential direction is not impaired.

Next, the main specifications of the actual embodiment are as follows.

・Depth H of main groove 10...13, Ov
avs・Width of main groove 10 W・・・・・・・・・10
, 5 vsva・Depth of hot water groove 30.・・・・・・2
．． 0fl・Width of water groove 30 B・・・・・・・・・・・・2
．． 0 fabric/width of rib 20 C・・・・・・・・・・・・23
．． 0ml/width of notch 21 A...3.0
mm・Depth of sipe 40 in the hot water groove hl...
...9.0 Tsuru/Yumizouchi Sipe 40 horizontal medium S...
......6.5mm Circumferential length of the sipe 40 in the hot water groove...12,0 Amount [Experimental example] (Experimental example 1) In this experimental example 1, the length of the rib 20 By variously changing the ratio S/C between the width C and the lateral medium S of the sipe 40 in the gutter, the gutter 3
0 disappears due to tire wear, the relationship between the wear amount of the heel and toe step formed before and after the sipe 40 in the tread groove and S/C, and the relationship between wet braking distance and S/C. Examined.

As a result of the experiment, the above heel and toe step wear amount and S/C
The results obtained are as shown in FIG. 4 for the relationship between , and FIG. 5 for the relationship between wet braking distance and S/C.

From the experimental results shown in FIG. 4, the value of the ratio S/C between the ri C of the rib 20 and the lateral medium S of the sipe 40 in the gutter is 0.4.
It can be seen that when the width exceeds 40%, that is, when the lateral center S of the sipe 40 in the gutter exceeds 40% of the width C of the rib 20, heel-and-toe wear becomes severe and uneven wear resistance decreases.

Furthermore, from the results of the experiment shown in FIG. 5, the value of the ratio S/C between the width C of the rib 20 and the width S in the lateral direction of the sipe 40 in the gutter is 0.2.
In other words, when the width of the sipes 40 in the lateral direction is less than
It can be seen that if C is less than 20% of the width C of the rib 20, the braking distance on a wet road surface becomes long and the wet braking resistance decreases.

In the end, from the results of the experiment shown in FIGS. 4 and 5, it was found that the width S of the sipe 40 in the gutter was 20 to 40 times the width C of the rib 20.
%, both uneven wear resistance and wet braking resistance can be improved.

(Experimental Example 2) In this Experimental Example 2, using the example tire of the present invention described above (see Figs. 1 and 2) and the comparative example tire shown in Fig. 6, the uneven wear resistance of each of these tires was determined. The performance and wet braking resistance were investigated.

"Specifications of the tires used in the experiment" - Example tire: Tire of the first embodiment of the present invention described above (see Figures 1 and 2) - Comparative tire Tire size: TBRlooOOR2014pHl
The main structure of a heavy-duty pneumatic radial tire with a groove pattern...as shown in Figure 6.

The specifications of the main parts are as follows.

・Pitch length a of the main groove formed in a zigzag shape...1
3.9n b...10.31m ・Zigzag amplitude d...2.5n Note that other parts that correspond to the example tire of the present invention shown in Fig. 1 are the same as the example tire. This is the specification.

(Experiment conditions) ・Vehicle...10 ton large truck (2-D・4)・
Internal pressure...8.0kg/c+a Heavy load...100χ load/braking distance on wet road Distance to stop when stepping on the brakes at a vehicle speed of 50km/hr/uneven wear after 40,000+n driving The uneven wear property, which was evaluated based on the width of the river wear abrasion generated in the groove, is expressed as an index with the measurement results of the comparative example tire set as 100. Therefore, the larger the value, the better.

As a result of the experiment, the results shown in Table 1 were obtained.

In addition, in the example tires of the present invention, heel end toe wear was suppressed to a satisfactory extent both when new and after the grooves had disappeared.

From Table 1, it can be seen that the example tires of the present invention can significantly improve uneven wear resistance and wet resistance compared to the comparative examples.

〔Effect of the invention〕

The present invention can significantly improve the uneven wear resistance and wet resistance of a heavy-duty pneumatic radial tire suitable for high-speed driving on good roads, which has a trend pattern as a rib pattern.

[Brief explanation of the drawing]

1 to 3 respectively show heavy-duty pneumatic radial tires according to embodiments of the present invention. FIG. 1 is a tread development view showing the main parts of the first embodiment, and FIG. −
■Explanatory cross-sectional view in the direction of arrows Figure 3 is a developed view of the tread showing the main parts of the second embodiment, Figure 4 is the ratio S/C of the width C of the rib to the lateral medium S of the sipe in the groove and uneven wear. Diagram showing the relationship with gender, No. 5
The figure shows the ratio S/ of the width C of the rib and the lateral medium S of the sipe in the gutter.
FIG. 6 is a tread development diagram showing the main parts of a conventional heavy-duty pneumatic radial tire. 10...Main groove 10c...Center side main groove 10s...Shoulder side main groove 10s 20...Rib 21...Notch 20c...Center rib 2On ... Intermediate rib 20s ... Shoulder rib 30 ... Hot water groove 31 ... ... Groove bottom 32 of hot water groove ... Circumferential portion 40 of hot water groove ... ... Sipe in the hot water groove C ... Rib width H ... Depth of the main groove 10 W ... Width of the main groove ho ... Depth of the hot water groove B ...Width of the hot water groove C...Middle of the rift A...Width of the notch hl...Depth of the sipe in the hot water groove

Claims (2)

[Claims] (1) The tire has a plurality of circumferential ribs partitioned by a plurality of main grooves extending substantially linearly in the circumferential direction of the tire, and at least one circumferential rib has a plurality of circumferential ribs extending laterally from the main grooves on both sides of the circumferential rib. A large number of notches having the same depth as the main groove are formed, the opposing notches are connected by a groove that is shallower and narrower than the main groove, and the groove is located in the center of the groove. A pneumatic radial tire for heavy loads, characterized in that sipes in the groove are arranged on the bottom along the groove within a range of 20 to 40% of the rib width C. (2) The heavy-duty pneumatic radial tire according to claim 1, wherein the hot water groove has a circumferential portion extending at a shallow angle in the circumferential direction at a central portion of the rib.