JP2505178B2 - Pneumatic radial tires for heavy loads - Google Patents

Description

The present invention relates to a heavy-duty pneumatic radial tire, and more specifically, to a heavy-duty pneumatic tire having a tread pattern as a rib pattern suitable for high-speed running on a good road. The present invention relates to improvement of uneven wear resistance and wet resistance.

[Conventional technology]

Conventionally, a tire using a rib pattern as a tread pattern is suitable for high-speed running on a good road, and good uneven wear resistance and wet resistance are important performance requirements.

However, the technique for improving the uneven wear resistance and the wet resistance is a contradictory technique, and conventionally, the following measures have been taken. That is, (1) a zigzag-shaped main groove having a small amplitude is provided to improve both traction and drainage on a wet road surface in order to achieve both the uneven wear resistance and the wet resistance. A shallow horizontal groove is placed in the rib to ensure traction and braking.

(2) Further, in order to improve the wet resistance, the molten metal groove provided in the rib is deepened or a deep sipe connected from the main groove to the main groove is provided.

[Problems to be solved by the invention]

However, with the above-mentioned means (1), as the tread surface of the tire is worn out, there is no way to remove the gutters, which inevitably reduces the traction and braking characteristics, while increasing the zigsag amplitude in the main groove to increase the traction. If this is done, uneven wear, which is called river wear, tends to occur, and the uneven wear resistance also deteriorates, which is not sufficient.

Further, the means of (2) has a problem that uneven wear called heel and toe wear easily occurs, and uneven wear resistance is deteriorated and is not sufficient.

By the way, the heel-and-toe wear is compared with the amount of wear of the block on the stepping side that comes into contact with the ground when the tire rolls on the road surface, out of the blocks formed by the gutters or sipes that cross the ribs. As a result of increasing the amount of wear of the so-called kick-out side block that comes into contact with the ground later, a wear step is formed before and after the molten metal groove or sipes. This uneven wear is called heel and toe wear.

In addition, the above-mentioned river wear wear means that the convex portion of the circumferential rib sectioned by the zigzag-shaped main groove arranged in the circumferential direction of the tire is worn as compared with the concave portion, and as a result, wavy along the rib. Wear occurs. This uneven wear is called river wear wear.

The present invention has been achieved as a result of experiments and examinations for solving the above-mentioned problems.

Therefore, an object of the present invention is to prevent early occurrence and growth of uneven wear such as heel-and-toe wear and river wear wear to significantly improve uneven wear resistance, and to obtain good wet resistance. It is to provide a pneumatic tire for heavy loads.

[Means for solving problems]

To achieve the above object, the present invention has a plurality of circumferential ribs defined by a plurality of main grooves extending substantially linearly in the circumferential direction of the tire, and the at least one circumferential rib has main ribs on both sides thereof. A large number of notches extending laterally from the groove and having a depth equivalent to that of the main groove are formed, and the facing notches are connected by a groove which is shallower and narrower than the main groove. It is characterized in that the sipes in the gutter are arranged along the gutter in the range of 20 to 40% of the rib width C at the bottom of the groove positioned at the center.

Further, the molten metal groove has a circumferential portion extending at a shallow angle in a circumferential direction at a central portion of the rib.

[Action]

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

Further, since at least one of the plurality of circumferential ribs partitioned by the main groove is formed with a large number of notches extending laterally from the main grooves on both sides thereof and having a depth equivalent to that of the main groove, Good traction can be maintained without lowering uneven wear.

Further, while connecting the cutout portion with a molten metal groove that is shallower and narrower than the main groove, while being positioned at the center of this molten metal groove, at the groove bottom,
By disposing the sipe in the gutter along the gutter within the range of 20 to 40% of the rib width, not only when it is a new product, but also after the gutter is worn, the traction property and the braking property in the initial stage of wear are shown. It is possible to maintain the above, and it is possible to prevent the deterioration of uneven wear resistance.

That is, even after the number of gutters is reduced as the tire wears, the sipe can be added to the groove bottom to maintain the traction property and the braking property and prevent the uneven wear resistance from being lowered.

Moreover, it is preferable that the above-mentioned molten metal groove has a circumferential portion extending at a shallow angle in the circumferential direction at the central portion of the rib.

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

That is, by arranging a circumferential portion extending at a shallow angle in the circumferential direction in the central portion of the rib, the rib rigidity in the central portion of the rib is weakened in a well-balanced manner, the movability of the rib is improved, drainage is enhanced, and the rib The grounding property can be improved.

Further, when the molten metal groove is arranged in a straight manner across the ribs and the circumferential portion is provided, the kicked-out portion is dispersed, and early occurrence of heel and toe wear and its growth can be suppressed, which is preferable. . Moreover, since the groove depth of the molten metal groove is shallow, it is possible to prevent the heel and toe wear from occurring at an early stage.

Further, as described above, the gutter disappears as the vehicle travels, so when using the sipe in the gutter as necessary to maintain wet performance, especially traction, until the end of wear, the gutter bottom of the gutter is preferably By disposing the sipe in the groove in the circumferential direction of the center of the rib where heel and toe wear is unlikely to occur, the problem of early occurrence of heel and toe wear at the initial stage of wear was solved.

Furthermore, by inserting the sipe in the gutter along the central part of the gutter, the effect of ensuring good wet performance during cornering when traveling on the wet road surface described above can be further enhanced in the initial stage of wear, and wear When the gasusumi gutter disappears, the above effect is exhibited in place of the gutter, and by increasing the circumferential portion, it is possible to effectively use the sipe that is likely to cause 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 each show a heavy-duty pneumatic radial tire according to an embodiment of the present invention, and FIG.
Tread development showing the essential parts of the embodiment, FIG. 2 is FIG. 1 II
-II arrow sectional view explanatory drawing FIG. 3 is a tread development drawing which shows the principal part of 2nd Example.

The size TB in the first and second embodiments shown in FIGS.
1 is an example in which the present invention is applied to a heavy-duty pneumatic radial tire having a rib pattern of R10000 R20 14PR.

The pneumatic radial tire for heavy loads according to each of the embodiments has at least 3 extending substantially linearly in the circumferential direction of the tire.
A plurality of circumferential ribs 20 are divided into treads by the main groove 10 of the book, and a large number of notches having the same depth as the main groove 10 extending laterally from the main groove 10 to the side of the rib 20 inside the rib 20. Having a part 21,
In the second rib 20n counting from the shoulder rib 20s on the shoulder side, the notch 21 to the notch 21 are connected by a shallow narrow groove 30. The groove 30 is formed at the center of the rib 20n in the tire circumferential direction. It has a circumferential portion 32 extending at a shallow angle with respect to the gutter 30.
The sipes 40 are arranged along the hot water groove 30 within the range of 20 to 40% of the rib width C on the groove bottom 31 at the center of the, and the remaining ribs 20 are the pneumatic radial for heavy load of the rib type pattern continuous in the circumferential direction. In the tire, the circumferential continuity of the remaining ribs 20 is not compromised by the placement of the short length sipes 50.

The structure will be further described. In each of the examples, four linear main grooves continuous in the circumferential direction on the tread surface of the tire are used.
10 are arranged.

Therefore, the ribs 20 defined by the four linear main grooves 10 are one center rib 20c formed between the two left and right center side main grooves 10c, and the two center sides described above. Two left and right intermediate ribs 20n formed between the main groove 10c and the left and right shoulder side main grooves 10s, and left and right formed on the tread ends of the left and right shoulder side main grooves 10s, that is, the left and right shoulder sides. Two shoulder ribs 20s
It is 5 in total.

Moreover, each of the ribs 20 described above is formed with a large number of notches 21 that extend laterally from the main grooves 10 on both sides thereof and have a depth equal to the depth H of the main grooves 10 at intervals.

The width A of the notch 21 is 10 to 20% of the width C of the rib 20.
It is preferable to set it within the range of (1) in order to maintain good traction and prevent the deterioration of uneven wear resistance.

Furthermore, each notch 21 described above in each of the embodiments,
As shown in the drawing, the notches 21 facing each other are arranged in a zigzag pattern.

In each of the embodiments, as shown in the drawing, the two left and right intermediate ribs 20n are connected with the facing notches 21 by a groove 30 which is shallower and narrower than the main groove 10. It is constructed by arranging the sipes 40 in the gutter 40 having a width S in the range of 20 to 40% of the width C of the ribs 20 on the groove bottom 31 so as to be positioned in the central part of the gutter 30. ing.

The width B of the gutter 30 is set within the range of 5 to 15% of the rib width C, while the depth h ₀ of the gutter 30 is set to the depth H of the main groove 10.
By setting it in the range of 10 to 20%, it is possible to maintain good traction performance and braking performance, and it is possible to prevent deterioration of uneven wear resistance.

Further, the circumferential length L of the sipe 40 in the gutter is a lateral width S.
1.5-2.5 times the depth h ₁ plus the depth h ₀ of the gutter 30 depth h ₂
Is set within the range of 70 to 90% of the depth H of the main groove 10 to prevent generation of heel and toe wear and reduce uneven wear resistance, and to obtain good wet performance until the end of wear. Can be maintained.

Further, the inclination angle of the sipe 40 in the gutter with respect to the tire circumferential direction is most preferably 0 °, but a shallow angle of 30 ° at the maximum can suppress the occurrence of heel end toe wear to a satisfactory degree. Therefore, the sipe in the gutter
The inclination angle of the gutter 30 provided with 40 with respect to the tire circumferential direction is optimally 0 °, 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 with the sipe 40 in the gutter, as shown in the drawing,
It is also possible to provide portions on both sides of 40 that extend in the tire axial direction.

This axial component provides the traction performance required for braking, etc., and the circumferential component provides the traction performance required for antiskid, etc.

Further, in the above-described gutter 30, as shown in FIG. 1 in the first embodiment, the notches 21 arranged in a zigzag pattern facing each other are selected so that the gutter 30 rises to the right. And they are connected.

In addition, in the second embodiment, as shown in FIG. 3, the cutouts 21 arranged in a zigzag pattern facing each other are formed in the gutters 30.
Are selected and connected so that they are on the lower right.

Further, in each of the embodiments, each of the grooves 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 20n.

Further, in each of the embodiments, four main grooves 10 are arranged as described above, but at least three or more main grooves may be 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 disposing such sipes 50 on the ribs 20, the circumferential continuity of the ribs 20 is not impaired.

 The main specifications of each embodiment are as follows.

・ Depth H of the main groove 10 ………… 13.0mm ・ Width W of the main groove 10 ………… 10.5mm ・ Depth h of the gutter 30 h ₀ ……… 2.0mm ・ Width B of the gutter 30 ……… … 2.0mm ・ Width of rib 20 C ………… 23.0mm ・ Width of notch 21 A ………… 3.0mm ・ Depth of sipe 40 in the gutter h ₁ ………… 9.0mm ・ Sipe 40 in the gutter Lateral width S of 6.5 mm-Lip length Sip 40 circumferential direction L of 12.0 mm [Experimental Example] (Experimental Example 1) In Experimental Example 1, the width C of the rib 20 and the siphon in the gutter
By changing the ratio S / C of the lateral width S of 40 to various values, the sipe 40 in the gutter 30 after the gutter 30 disappears due to tire wear,
The relationship between the heel-and-toe step wear amount before and after the sipe 40 in the gutter and S / C, and the relationship between the wet braking distance and S / C were examined.

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

From the results of the experiment shown in FIG. 4, when the ratio S / C between the width C of the rib 20 and the lateral width S of the sipe 40 in the gutter exceeds 0.4,
That is, the lateral width S of the sipe 40 in the gutter is equal to the width C of the rib 20.
It can be seen that if it exceeds 40%, heel and toe wear becomes severe and uneven wear resistance decreases.

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

After all, from the results of the experiments shown in FIGS. 4 and 5, it is found that the lateral width S of the sipe 40 in the gutter 40 is set to be within the range of 20 to 40% of the width C of the rib 20. It can be seen that both the resistance to wet braking and the resistance to wet braking can be improved.

(Experimental Example 2) In 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 used. And wet braking resistance were investigated.

"Specifications of Tires Used for Experiments" -Example tires ... Tires of the above-described first example of the present invention (see Fig. 1 and Fig. 2) -Comparative example tires Tire size ... TBR10000 R20 14PR rib pattern Pneumatic radial tire for heavy loads Main structure: As shown in Fig. 6.

 The specifications of the main part are as follows.

-Pitch length of the main groove formed in a zigzag shape a ... 13.9 mm b ... 10.3 mm-Zigzag amplitude d ... 2.5 mm A portion corresponding to the embodiment tire of the present invention shown in Fig. 1 in other portions Has the same specifications as the example tire.

(Experimental conditions) ・ Vehicle: 10ton heavy truck (2-D ・ 4) ・ Internal pressure: 8.0kg / cm ²・ Load: 100% load ・ Brake distance on wet road surface Stopping when the brake is applied at a vehicle speed of 50kg / hr Distance / Uneven wear property Evaluated by the width of riverwear wear that occurs in the main groove after running 40,000 km. Uneven wear property is indicated by an index with the measurement result of the comparative tire as 100. Therefore, the larger the value, the better.

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

In the tires of the examples of the present invention, heel and toe wear was suppressed to a satisfactory level when the tire was new and after the melt groove disappeared.

It can be seen from Table 1 that the example tires of the present invention can greatly improve the uneven wear resistance and the wet resistance as compared with the comparative examples.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The present invention can greatly improve the uneven wear resistance and wet resistance of a heavy-duty pneumatic radial tire suitable for high-speed running on a good road using a tread pattern as a rib pattern.

[Brief description of drawings]

1 to 3 each show a heavy-duty pneumatic radial tire according to an embodiment of the present invention, FIG. 1 is a development view of a tread showing an essential part of the first embodiment, and FIG. −
II Cross-sectional explanatory view taken in the direction of arrow FIG. 3 is a development view of the tread showing the essential parts of the second embodiment, and FIG. FIG. 5 shows the relationship between the wet width braking distance and the ratio S / C of the width C of the ribs to the lateral width S of the sipes in the gutter, and FIG. It is a tread development drawing showing the important section of a heavy duty important pneumatic radial tire. 10 …… Main groove 10c …… Center side main groove 10s …… Shoulder side main groove 10s 20 …… Rib 21 …… Notch 20c …… Center rib 20n …… Intermediate rib 20s …… Shoulder rib 30 …… Mix groove 31 …… Bottom of the gutter 32 …… Circumferential part of the gutter 40 …… Sipe inside the gutter C …… Width of the rib H …… Depth of the main groove W …… Width of the main groove h ₀ …… Depth of groove B …… Width of gutter C …… Width of rib A …… Width of notch h ₁ …… Depth of sipe in the gutter S …… Horizontal width of sipe in the gutter L …… Circumferential length of sipe in groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-61008 (JP, A) JP-A-61-181704 (JP, A) JP-A-55-123507 (JP, A) JP-A-55- 94802 (JP, A) Actually opened 61-132105 (JP, U) JP 53-30202 (JP, B2) JP 58-11324 (JP, B2) JP 4-40206 (JP, B2) JP-B 2-324802 (JP, B2) JP-B-57-9966 (JP, B2) JUKI 3-26964 (JP, Y2)

Claims (2)

(57) [Claims] 1. A tire having a plurality of circumferential ribs defined by a plurality of main grooves extending substantially linearly in the circumferential direction of the tire, wherein the at least one circumferential rib extends laterally from the main grooves on both sides thereof. Form a number of notches that extend and have a depth equivalent to that of the main groove, connect the facing notches with a shallower and narrower groove than the main groove, and position it at the center of the groove. The radial radial tire for heavy load is characterized in that a sipe in the gutter is arranged along the gutter on the groove bottom within a range of 20 to 40% of the rib width C. 2. The pneumatic radial tire for heavy load according to claim 1, wherein the molten metal groove has a circumferential portion extending at a shallow angle in the circumferential direction at a central portion of the rib.