JPH0218106A - Pneumatic tyre - Google Patents

Abstract

PURPOSE:To improve soft road-surface running performance without the drop down of hard road-surface running performance of a tyre by taking steps of the provision, of a specific base part and top end part and the like in slant grooves extending slantingly toward first circumferential direction grooves from both ends of a tread. CONSTITUTION:A first circumferential direction groove 10 extending in a zigzag shape toward the circumferential direction in the equatorial direction of the tyre, a pair of second circumferential direction grooves 20A, 20B extending toward the circumferential direction between the first circumferential direction groove 10 and both ends of the tread and plural slant grooves 30 extending slantingly toward the first circumferential direction groove 10 from both ends of the tread are formed in the tread T of a tyre. Plural land parts 40A-40D are partitioned by the above respective grooves 10-30. In this case, base parts 31 with comparatively wide grooves positioned on the tread end part and top end parts 32 with comparatively narrow grooves ending inside of respective land parts 40B, 40C staying between the first and second respective circumferential direction grooves 10, 20A, 20B are provided in the slant grooves 30.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to the improvement of pneumatic tires, and more specifically, to the improvement of pneumatic tires that can improve the running performance on soft roads without reducing the running performance on hard roads. It is related to tires.

(Prior Art) Typical tire tread patterns include rib patterns, lug patterns, block patterns, and rib-lug patterns, which are used depending on the required performance of the tire.

Tires for running on soft and hard roads, such as conventional commercial vehicles and off-road leisure vehicles that often drive on soft roads, are shown in Figures 2 and 3 depending on the purpose of use. As shown, tread patterns are broadly divided into two types: a type that emphasizes running on hard roads and a type that emphasizes running on soft roads.

That is, FIG. 2 is a developed view of the tread of a conventional hard road-oriented tire, in which three circumferential grooves IA, IB, and IC extend in a zigzag manner in the circumferential direction, and the circumferential groove IB extends from both ends of the tread. and a number of lateral grooves 2A, 2B, 2C... extending across the IC to the circumferential groove IA.
By, multiple deformed blocks 3A, 3B, 3C13D
... is formed, and each block has sipes (cuts)
4 is provided to increase frictional resistance with the road surface.

This tire that focuses on driving on hard roads generally has a negative rate (
The area ratio of the groove portion is set so as not to be too large, and the groove width between each block is often substantially equal.

On the other hand, FIG. 3 is a tread development view of a conventional tire that emphasizes running on soft roads, which includes a linear circumferential groove IA, a pair of zigzag circumferential grooves IB provided on both sides of the circumferential groove IA, The circumferential groove IB from both ends of the IC and tread
A plurality of deformed blocks 3A, 3B, 3C13D, . . . are formed by a large number of wide lateral grooves 2A, 2B, 2C, . . . extending across the IC to the circumferential groove IA.

These soft-road-oriented tires generally have a thick negative ratio, and the width of the lateral grooves, which have a particularly large cross-sectional directionality, are set wide.

(Problems to be Solved by the Invention) However, although the conventional hard road tires and soft road tires described above are strong on their respective specialized roads, their fundamental design philosophy, such as the method of setting the negative rate, is Due to the differences in performance, the road performance for non-specialists was not necessarily satisfactory.

In other words, conventional tires designed for running on hard roads exhibit sufficient block rigidity and smooth ground contact when running on hard roads, and have excellent performance such as straight-line running and handling. When driving on a soft road surface, there is a problem in that effective traction performance cannot be obtained.

In addition, conventional tires designed for running on soft roads exhibit strong traction and excellent running performance when running on soft roads, but when running on hard roads, they lack block rigidity and have discontinuous ground contact. Therefore, there was a problem that various driving performance and living performance were inferior.

Therefore, an object of the present invention is to solve the problems of the conventional pneumatic tires mentioned above.

Therefore, an object of the present invention is to provide a pneumatic tire that can improve performance on soft roads without reducing performance on hard roads.

[Structure of the Invention] (Means for Solving the Problems) That is, the pneumatic tire of the present invention includes a cylindrical tread and a pair of sidewalls extending radially inward from both ends of the tread, wherein the tread is substantially A first circumferential groove extending in a zigzag manner in the circumferential direction at the equator position of the upper tire, and a pair of second circumferential grooves extending in the circumferential direction between the first circumferential groove and both ends of the tread. , consisting of a plurality of inclined grooves extending obliquely from both ends of the tread toward the first circumferential groove and arranged at predetermined intervals in the circumferential direction, and a land section divided by a group of these grooves. In the tire, the second circumferential groove has a zigzag shape whose upper limit is the amplitude of the first circumferential groove, or a circumferential flow whose lower limit is a substantially straight line parallel to the equator, and the inclined groove has , comprising a base portion located at the end of the tread and having a relatively wide groove width, and a tip portion having a relatively narrow groove width and terminating within a land portion between the first circumferential groove and the second circumferential groove. shall be.

(Function) The pneumatic tire of the present invention can appropriately set a lag component effective for running on soft roads without increasing the negative ratio.

That is, by providing a first circumferential groove extending in a zigzag shape in the circumferential direction in the central area of the tread, and a pair of second circumferential grooves having a smaller amplitude than the first circumferential groove, traction when running on a soft road is improved. The effect can be increased.

In addition, by extending the inclined grooves from both ends of the tread across the second circumferential direction and arranging them so that they do not terminate at the first circumferential grooves, the grooves are common to both running on soft and hard roads. effective traction effect is demonstrated,
Furthermore, the ground contact during tire rotation becomes smoother, and deterioration of noise can be prevented.

Furthermore, by making the groove width at the base of the inclined groove at both ends of the tread larger than the groove width at the end, both end areas of the tread exhibit particularly strong traction effects, making it easier to drive on soft and hard surfaces. In both cases, excellent traction effects can be obtained.

Therefore, the pneumatic tire of the present invention can improve the running performance on soft roads without deteriorating the running performance on hard roads, and is particularly suitable for common use on soft and hard roads such as commercial and off-road leisure. Useful for moving type vehicles.

(Example) Hereinafter, examples of the pneumatic tire of the present invention will be described in detail according to the drawings.

FIG. 1 is a developed view of a tread showing an embodiment of the pneumatic tire of the present invention.

Note that although parts other than the tread T are not shown in FIG. 1, the other parts have a well-known structure.

In FIG. 1, the tread T of the tire includes a first circumferential groove 10 that extends in a zigzag shape in the circumferential direction substantially at the equator position of the tire, and between this first circumferential groove 10 and both ends of the tread, A pair of second circumferential grooves 2OA, 20B each extending in the circumferential direction, and a plurality of second circumferential grooves 2OA, 20B extending obliquely from both ends of the tread toward the first circumferential groove 10, and arranged at predetermined intervals in the circumferential direction. The inclined grooves 30 and land areas 40A, 40B, 40C140D divided by these groove groups
It consists of

The inclined groove 30 terminates within the base portion 31 located at the tread end and having a relatively wide groove width, and the land portions 40B and 40C between the first circumferential direction 110 and the second circumferential grooves 20A and 20B. It has a tip portion 32 with a relatively narrow groove width.

Here, the first circumferential groove 10 provided in the central area W1 of the tread (ground contact portion) T has an amplitude t of usually 10 to 1
It has a zigzag shape on five sides, which enhances the traction effect when driving on soft roads.

Further, although the pair of second circumferential grooves 20A and 20B arranged on both sides of the first circumferential groove 10 are shown as straight lines in the drawings, they have a zigzag shape having a width smaller than that of the first circumferential grooves 10. It can also be configured as follows.

The groove width of the first circumferential groove 10 and the second circumferential groove 20A, 20B is usually in the range of 5 to 10 m,
The groove width of the second circumferential grooves 2OA and 20B is the same as that of the first circumferential groove 10.
It is desirable to set the groove width to be equal to or slightly narrower than the groove width.

The inclined grooves 30 extend from the tread ends of each side area W2 of the tread divided by the second circumferential grooves 2OA and 20B, across the second circumferential grooves 20A and 20B, and extend into the first circumferential grooves. 10 without opening, and this configuration provides effective traction both when driving on soft and hard roads, and also provides smooth ground contact and noise reduction when the tire rotates. The prevention of

Here, the base 31 located at the tread end of the inclined groove 30
groove width L1, the first circumferential groove 10 and the second circumferential groove 20A.
, 20B, the groove width L2 of the tip end portion 32 that terminates within the land portions 40B and 40C is such that L1 is 5 to 5 of the tread width TW.
It is important that the ratio is 25%, especially 10 to 15%, and that Ll>L2, and by configuring it in this way, a strong traction effect can be obtained in the tread end region.

That is, if the groove width L1 of the base 31 is narrow, drainage performance is poor and mud gets clogged, and sufficient traction cannot be achieved when running on soft roads.On the other hand, if the groove width L1 is too wide, the block rigidity of the tread end area is reduced. This is undesirable because it becomes insufficient and causes problems when driving on hard roads.

Although the drawings show an example in which the groove width of the inclined groove 30 is reduced in a stepwise manner, the groove width may be gradually reduced from the tread end to the terminal end.

In addition, the inclined groove 30 may have a curved shape as shown in the figure.
They can also be arranged in a straight line.

Furthermore, the first circumferential grooves 1020A and 20 of the inclined #l bank 30
Preferably, the portion of the tip 32 that traverses B and terminates within the blocks 40B, 40C is sloped parallel to the sloped portion of the adjacent first circumferential groove 10, as shown.

Also, the slope? The terminal position of 1I30 is block 40B,
40C, it is desirable to set the position to be approximately 10 to 20 degrees closer to the first circumferential self-extinguisher 10 from the second circumferential grooves 20A and 20B.

The depth of each groove is in the range of about 10 to 12- for the first circumferential groove 10, and when the depth of the first circumferential groove 10 is 1,
It is preferable to set the depth of the second circumferential grooves 20A, 20B to be in the range of 1 to 0.8, and the depth of the inclined groove 30 to be in the range of 1 to 0.5.

In the drawings, an auxiliary groove 50 is further provided from the tip 31 of each inclined groove 30 to the first circumferential groove 10 to form a block pattern, but it is not necessary to provide this auxiliary groove 50. , it can also be formed as a glue pattern without auxiliary grooves.

Furthermore, in the drawings, each cavity 40A, 40B, 40
C140D is provided with sizes (cuts) Sl, S2, S3, and S4 for making the rigidity uniform, but the shape of these sizes and whether or not they are installed are also arbitrary.

Next, the structure and effects of the pneumatic tire of the present invention will be further explained using test examples.

(Test Example) The pattern shown in FIG. 1 described above was formed on the tread of a radial tire with a tire size of 205/75R15, and this tire was evaluated.

The other structure and manufacturing conditions of the tire are similar to those of conventional tires, so details will be omitted.

That is, in FIG. 1, the tread width TW: 150 m,
Central area @WI near 0m, width W2 of both sides: 40 each
m, groove width near garden of the first circumferential groove 10, depth: 11 degrees, swing width t: 13 nm, straight second circumferential grooves 20A, 20
The groove width of B is set to 5 am and the depth is 11 mm, and a second circumferential groove 20A is provided from the tread end in each of the both side areas.
20B, an inclined groove 30 that terminates approximately at the center of the cavities 40B and 40C without opening into the first circumferential groove 10;
has been established.

Base part 31 of inclined groove 30 @L1: 20m, tip part 32
The groove width L2 is 8 m, and the inclination angle of each inclined groove 30 is set so that when the tire is rotated in the direction of arrow A, it contacts the road surface sequentially from the center of the tire to the tread edge. The angles were arranged so as to gradually decrease from 50 to 20 degrees to the ends.

The negative rate of this tire was about 40%.

On the other hand, for comparison, a hard road oriented tire A (negative rate: 4
0%) and soft road oriented tire B shown in Figure 3.
(Negative rate: 50%) was created.

These three types of tires were evaluated in terms of traction, mud-clogging, ride comfort, pattern noise, straight-line performance, and cornering performance through an actual vehicle feeling test (internal pressure and load were JIS standard conditions) using the following criteria. Shown in the table.

, E no W The traction force when driving straight on a muddy soft road is measured using a load cell.

The amount of mud clogged in the tread pattern is measured after driving a certain distance on a soft, muddy road.

Test driver's feeling evaluation on a general hard road paved by Higashishinya.

Shorinia / General hard paved road, 1100k/h, 880-
Direct evaluation of the feeling when driving meandering at 560km and 40km.

Yu: Evaluation of the test driver's feeling on a general hard road paved with rough edges.

(The values in the following table are all index evaluations when the conventional tire A is set as 100, and the larger the index, the better the result.) (Left below) Table (Index is large) The above results It is clear from the above that the pneumatic tire of the present invention has improved performance on soft roads without deteriorating performance on hard roads.

[Effects of the Invention] With the configuration as described above in detail, it is possible to appropriately set the lag component effective for running on soft roads without increasing the negative chip rate.

That is, by providing a first circumferential groove extending in a zigzag shape in the circumferential direction in the central area of the tread, and a pair of second circumferential grooves having a smaller amplitude than the first circumferential groove, traction when running on a soft road is improved. The effect can be increased.

In addition, by extending the inclined grooves from both ends of the tread across the second circumferential groove and arranging them so that they do not terminate at the first circumferential groove, the grooves are common to both running on soft and hard roads. effective traction effect is demonstrated,
Furthermore, the ground contact when the tires rotate becomes smoother, and deterioration of noise can be prevented.

Furthermore, by making the slope at the base of the inclined groove at both ends of the tread larger than the slope at the end, both end areas of the tread exhibit a particularly strong traction effect, which improves both running on soft and hard roads. Commonly, excellent traction effects can be obtained.

Therefore, the pneumatic tire of the present invention can improve the running performance on soft roads without deteriorating the running performance on hard roads, and is particularly suitable for common use on soft and hard roads such as commercial and off-road leisure. Useful for moving type vehicles.

[Brief explanation of the drawing]

Fig. 1 is a developed view of a tread showing an embodiment of a pneumatic tire according to the present invention, Fig. 2 is a developed view of a tread of a conventional pneumatic tire designed for running on hard roads, and Fig. 3 is a developed view of a tread of a conventional pneumatic tire designed for running on hard roads. FIG. 2 is a developed view of a tread of a focused pneumatic tire. T... Tread 10... First circumferential groove 2OA... Second circumferential inner groove 20B... lI 30... Inclined groove 31... Base 32... Tip portion 40A... Land portion 40B...lI 40C...lI 40D...〃 50...Auxiliary groove Sl...Size S2...ll 53...11 S4...〃

Claims (1)

[Claims] a first circumferential groove including a cylindrical tread and a pair of sidewalls extending radially inward from both ends of the tread, the tread extending in a zigzag shape in the circumferential direction substantially at the equator position of the tire; A pair of second circumferential grooves each extending in the circumferential direction between the first circumferential groove and both ends of the tread.
a circumferential groove, a plurality of inclined grooves extending obliquely from both ends of the tread toward the first circumferential groove and arranged at predetermined intervals in the circumferential direction, and a land area divided by a group of these grooves. The second circumferential groove has a zigzag shape whose upper limit is the amplitude of the first circumferential groove or a circumferential flow whose lower limit is a substantially straight line parallel to the equator, and The inclined groove has a base portion located at the end of the tread and having a relatively wide groove width, and a tip portion having a relatively narrow groove width that terminates within a land portion between the first circumferential groove and the second circumferential groove. A pneumatic tire characterized by: