JPS62113607A - Radial tire for small size truck - Google Patents

Abstract

PURPOSE:To obtain an all-weather type tire, by forming auxiliary grooves in each block in the shoulder section, and by alternately arranging two kinds of auxiliary grooves having a specified ratio of the depth thereof with respect to the depth of main grooves in each block in the center section. CONSTITUTION:Auxiliary grooves 7, 8 are formed in the tire-radial direction in each block 2 in the shoulder section so that the block 2 is sectioned. Auxiliary grooves 3 through 6 are similarly formed in each block 1 in the center section. Further, the depth of the auxiliary grooves 3, 5 in each block 1 in the center section is set to be 45-55% of the depth of main grooves (a) while the depth of the auxiliary grooves 4, 6 is set to be 18-25% of the depth of the main grooves (a). With this arrangement, it is possible to obtain an all- weather type tire satisfying both wear-resistant capability and snowmobility.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an all-weather vehicle that runs on fair roads and snowy roads.
- Concerning improvements in the tread pattern of type radial tires for light trucks.

[Prior art]

Generally, tires are broadly classified into summer tires and winter tires.

In recent years, due to changes in road conditions such as the development of expressway networks, the number of vehicles traveling long distances has increased, the distance that cargo must be transported per day has become longer, and transport time has also become shorter. .

When driving long distances, vehicles are required to drive vehicles depending on their intended purpose, as the climate, temperature, etc. change depending on the region, and road conditions are not always constant, and there are roads that can be driven at high speeds, ordinary roads, snowy roads, wet roads, etc. You must experience driving on various road surfaces before you hit the ground running.

Also, as you enter the mountains, the road surface changes constantly.

Under these circumstances, it is impossible to install tires on a vehicle that match the climate and road surface.

In order to meet such social needs, all-weather type tires have been proposed that have both the performance of summer tires and the performance of winter tires.

Summer tires are designed to have heat resistance, high speed performance, abrasion resistance, and uneven wear resistance because they are used for driving at relatively high speeds, during periods of high temperature, and are mainly used for driving on good roads. Because of the important considerations, many tread patterns have relatively shallow grooves and are mainly based on a lip pattern. FIG. 6 shows an example of a tread pattern of a summer tire. In Fig. 6, a is the tire circumferential direction EE'
This is a main groove provided in an annular shape.

In addition, winter tires have a tread pattern based on fine blocks, with consideration given to driving force, braking force, and climbing force on snowy roads in order to increase safety on snowy roads.

Of course, winter tires also require the same wear resistance and uneven wear resistance as summer tires, but because of the tread pattern based on fine blocks, it is difficult to achieve the same level of performance as summer tires. Have difficulty. FIG. 7 shows an example of a tread pattern of a winter tire.

In FIG. 7, a indicates a main groove annularly provided in the tire circumferential direction EE', and b indicates a sub-groove provided in the tire radial direction (tire width direction).

Further, C represents a block.

In this way, summer tires and winter tires have tread patterns that suit their respective performance requirements. The difficulty in designing an all-weather type tire lies in the fact that it must combine both of these performances.

In general, all-weather type tires must have both abrasion resistance and uneven wear resistance, which are mainly required of summer tires, and performance on snow, which is required of winter tires. The tread pattern of this all-weather type tire often has blocks larger than those of winter tires. This is due to the fact that continuous ribs in the circumferential direction, such as summer tires, do not have enough driving force and braking force on snowy roads, and fine block blocks, such as winter tires, cause large movements of the rubber during driving, resulting in durability. This is because the abrasion resistance is extremely lower than that of summer tires.For this reason, all-weather type tires use blocks in consideration of their performance on snowy roads. The blocks are made larger in order to improve the wear resistance of tires.

FIG. 8 shows an example of the tread pattern of an all-weather type tire. In FIG. 8, as in FIG. 7, a indicates a main groove annularly provided in the tire circumferential direction EE', and b indicates a sub-groove provided in the tire radial direction. C represents a block.

However, the required performance of a summer tire and the required performance of a winter tire are in a trade-off relationship in terms of the block design, in view of the movement of the tread pattern during running. Various improved techniques for this purpose have been proposed, but none have been established yet. For example, the main improvements in this technology involve the shape, arrangement, and size of the blocks; however, if the blocks are small, the snow performance will be good, but the wear resistance will be poor; if the blocks are large, the durability will be poor. The general tendency is that the wear resistance is good, but the snow performance is poor.

Therefore, at present, no all-weather type tire with excellent wear resistance and excellent performance on snow has been proposed.

[Purpose of the invention]

The present invention was developed in view of these circumstances, and solves the design problems of the blocks by arranging appropriate auxiliary grooves on the blocks in the tread pattern, thereby improving both wear resistance and on-snow performance. All that satisfied
The purpose of the present invention is to provide a weather type radial tire for small trucks.

[Structure of the invention]

Winter tires have finer blocks in the tread pattern with sufficient space around the blocks to allow snow to dig into the grooves, making it easier to use the shearing force of the snow to provide driving and braking power. In addition, the ratio of the actual ground contact area to the total ground contact area of the tire is set at 40 to 50%. In addition, in conventional all-weather type tires, the blocks are small, so the blocks tend to move on good roads, resulting in rapid wear.

Therefore, as a result of various studies, the inventors of the present invention improved the wear resistance by increasing the ratio of the actual ground contact area to the total ground contact area of the tire to around 50%, and further improved the snow performance by providing auxiliary grooves on the blocks. It has been found that the above objective can be achieved by arranging auxiliary grooves in the tire radial direction.

Therefore, the present invention provides a tread pattern in which blocks are formed by providing a plurality of main grooves annularly in the tire circumferential direction on the tire tread surface and arranging sub-grooves in the tire radial direction on the tire tread surface. (2) At least one auxiliary groove is provided in the center block between both shoulder sections in the tire radial direction to divide the block, and (2) at least three auxiliary grooves are provided in the center block between both shoulder sections to divide the block.
Further, (3) the depth of the auxiliary grooves in the center portion is alternately set to 18 to 25% and 45 to 55% of the depth of the main groove. This article focuses on radial tires for small trucks that have special characteristics.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of the tread pattern of the tire of the present invention. In FIG. 1, a plurality of main grooves a are annularly provided in the tire tread surface in the tire circumferential direction EE', and a plurality of sub-grooves are arranged in the tire radial direction to form a plurality of blocks. 1 indicates the center block, and 2 indicates the shoulder block.

FIG. 2 is a partially enlarged view of the tread pattern of FIG. 1. In FIG. 2, an auxiliary groove 7 is provided in the block 2 of the shoulder portion in the tire radial direction to divide the block, and an auxiliary groove 8 is further provided in the tire radial direction. Four auxiliary grooves 3, 4, 5, and 6 are provided in the center block 1 between both shoulder sections in the tire radial direction to divide the block.

The depth of the auxiliary grooves 3 and 5 is 45 to 55% of the depth of the main groove a, and the depth of the auxiliary grooves 4 and 6 is 1% of the depth of the main groove a.
It is 8-25%. In this way, the auxiliary groove 3 in the center part
．． The depth of 4.5.6 is alternately 18 to 18 of the depth of the main groove a.
25% and 45-55%.

Auxiliary groove 3. 4. 5. 6, 7, and 8 relative to the tire circumferential direction EE'' (representatively shown for auxiliary tI4 in Fig. 2) should be 60° to 90° on the acute angle side to ensure good driving and braking performance on snow. preferred for.

FIG. 3 shows the relationship between this angle α, braking on snow, and drivability. FIG. 3 shows a case where the snow braking and driving performance of a general-purpose snow tire (winter tire) is set to 100. From FIG. 3, it can be seen that α is 60° and 93.90°, which is 110.

93 Ruheruha, Practical 4' [Upper level, it has been confirmed that there are no problems.

The angle β of the auxiliary grooves 3.4, 5.6, and 7, 8 with respect to the block contour (representatively shown for the auxiliary groove 3 in Fig. 2) should be 30" or more on the acute angle side to ensure the durability of the block itself. This is preferable in order to improve uneven wear resistance.This is clear from the results obtained from the tires after running on general roads (10,000 km) shown in Fig. 4.In Fig. 4,
The vertical axis is the difference (mm) in the amount of wear between the two blocks divided by the auxiliary groove. According to FIG. 4, it can be seen that when β is 30'' or more, the difference in wear amount is extremely reduced.

Auxiliary groove 3. 4. 5. Width χ of 6, 7, 8 (second
In the figure, the auxiliary fi3 is shown as a representative) is 0.5 to 1 Omm, considering snow performance and wear resistance performance.
It is preferable that This is because if the thickness is less than 0.5 mm, the snow will dig into the snow worse on snowy roads, reducing snow braking and driving performance, while if it exceeds 1.0 mm, the movement of the divided blocks will become thicker. This is because the wear resistance deteriorates.This is clear from FIG.

Figure 5 shows the width χ of the auxiliary groove and the mileage per millimeter (103k
m/mm), braking on snow, and drivability.

In Fig. 5, ◯ indicates the mileage per millimeter, and △ indicates snow braking and drivability. From Figure 5, the width χ of the auxiliary groove is 0.
．． It can be seen that in the case of 5 to 1 Omm, both the mileage per millimeter and the braking and drivability on snow are good.

〔Effect of the invention〕

As explained above, according to the present invention, an auxiliary groove is provided in each block in the tread pattern in which blocks are formed, and deep auxiliary grooves and shallow auxiliary grooves are alternately arranged in the center block. - It is possible to achieve both snow performance and wear resistance, which were difficult to achieve with weather type tires.

Furthermore, according to the present invention, since appropriate radial auxiliary grooves are arranged in the blocks, the uneven wear that occurs in conventional block-type tread patterns can be reduced to one level.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the trend pattern of the tire of the present invention, and FIG. 2 is a partially enlarged view of the tread pattern of FIG. 1. Figure 3 is a diagram of the relationship between the angle α of the auxiliary groove with respect to the tire circumferential direction, braking on snow, and drivability. Figure 4 is the relationship between the angle β of the auxiliary groove with respect to the block contour and the difference in the amount of wear between both blocks divided by the auxiliary groove. FIG. 5 is a diagram showing the relationship between the width χ of the auxiliary groove and the mileage per millimeter, braking on snow, and drivability. Figure 6 is an explanatory diagram showing an example of a tread pattern for a summer tire, Figure 7 is an explanatory diagram showing an example of a trend pattern for a winter tire, and Figure 8 is an explanatory diagram showing an example of a tread pattern for an all-weather type tire. It is an explanatory diagram showing an example. ■... Center block, 2... Shoulder block, 3.4, 5, 6, 7° 8... Auxiliary groove, a
...Main groove, b...Sub groove, C...Block.

Claims (1)

[Claims] In a tread pattern in which blocks are formed by annularly providing a plurality of main grooves in the tire circumferential direction on the tire tread surface and arranging sub-grooves in the tire radial direction on the tire tread surface, (1) the block in the shoulder portion has the blocks; At least one auxiliary groove dividing the tire is provided in the tire radial direction,
(2) At least three auxiliary grooves are arranged in the tire radial direction to divide the block in the center part between both shoulder parts, and (3) the depth of the auxiliary grooves in the center part is alternated. 18~25% of the depth of the main groove and 45~
A radial tire for small trucks characterized by a 55% tire.