JPH02179508A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce the noise and rolling resistance from the unused time to the early stage of abrasion and improve the steering stability and deflected abrasion resistance by chamfering the edge part of a block formed on a tire tread and setting the chamfering angle within a specified numerical range. CONSTITUTION:Main grooves 2 in the tire circumferential direction E, E' and sub-grooves 3 in the tire lateral direction F, F' are disposed on a tire tread 1, whereby blocks 4 and ribs 5 are formed. In this case, the edge parts 6 of the blocks 4 are chamfered over the nearly whole circumference of the blocks 3. The chamfering angle alpha which is the angle of the chamfering to the tire tread is set within the range of 5 deg.-30 deg.. The chamfering depth h is, for example, about 0.2mm-2.0mm, preferably about 0.6mm-1.4mm. Hence, the noise and rolling resistance of the tire from the unused time to the early stage of abrasion are reduced, and the steering stability and deflected abrasion resistance are improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention reduces noise and rolling resistance from when new to the initial stage of wear (when traveling approximately 6,000 km), and improves handling stability and uneven wear resistance. Regarding improved pneumatic tires.

[Conventional technology]

In a pneumatic tire having a block-based tread pattern, as illustrated in FIG. 8, a main groove 2 is provided on the tread 1 in the tire circumferential direction BE', and a minor groove 3 is provided in the tire width direction FF'. , and blocks 4 and ribs 5 are formed. However, in these blocks 4 and ribs 5, as shown in FIG. 9, which shows an enlarged cross section of A-A in FIG. A problem arises. Note that these problems are noticeable from when the tire is new until the beginning of wear, and then decrease as the wear progresses.

■When the tire rotates, the edge suddenly comes into contact with the road surface, and the edge vibrates when stepping on or kicking off, which generates high-frequency noise. ■As the edge part undergoes large deformation when stepping on the pedal, heat generation increases and rolling resistance increases.

■When a force in the tire width direction is applied to the block during cornering, or a force in the tire circumferential direction is applied to the block during braking, stress concentrates near the edge and other parts do not work effectively, resulting in a worsening of steering stability. do. ■Because the edge portion has low rigidity, there is a large difference in the amount of wear between the stepping side and the kicking side, which tends to cause uneven wear, which increases noise during driving.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned problems, and by devising the shapes of blocks and ribs on the tire tread, it reduces noise and improves rolling resistance. It is an object of the present invention to provide a pneumatic tire with reduced wear resistance and further improved handling stability and uneven wear resistance.

[Means to solve the problem]

The present invention provides a pneumatic tire having a block-based tread pattern on the tire tread surface, in which at least the edge portion of the block is chamfered over almost the entire circumference of the block, and the chamfer angle is set to 5'' to 306 mm with respect to the tread surface. This article focuses on pneumatic tires that are characterized by:

This means will be explained in detail below with reference to the drawings. Note that the same parts and parts as in FIGS. 8 and 9 are represented by the same numbers.

FIG. 1 is an explanatory plan view showing an example of the tread pattern of the pneumatic tire of the present invention.

In FIG. 1, a tread 1 is provided with a main groove 2 in the tire circumferential direction EE°, a sub-groove 3 in the tire width direction FF', and blocks 4 and ribs 5. The edge portion 6 of the block 4 is chamfered, as shown in FIG. 2 as an enlarged cross-section taken along the line B--B in FIG. 1. This chamfering is performed over almost the entire circumference of the block 4, as shown in FIG.

Further, the chamfer angle α is 5″ to 30″, preferably 10° to 20＠. Here, the chamfer angle α is
The angle relative to the tire tread.

If the chamfering angle α is less than 5°, the chamfering effect will hardly be exhibited, while if it exceeds 30＠, the block rigidity will decrease, resulting in insufficient steering stability.

The chamfer depth h is about 0.21IIll to 2.0 mm, preferably about 0.6++ua to 1.411II+.

It is preferable that both blocks and ribs be chamfered in this way, but it is preferable to chamfer at least the blocks.The blocks to be chamfered are 50% or more of the blocks existing on the tread l. Good to have,
In particular, in order to improve uneven wear resistance and handling stability during cornering, it is preferable that all blocks present in a portion of the sillage of the tread 1 be chamfered.

When driving with a tire that has a trend pattern based on chamfered blocks, when the tire rotates in the direction of rotation shown by the arrow T, the surfaces of the blocks 4 and the edges 6 are smooth against the road surface M, as shown in FIG. Because it is in contact with the ground, no vibration is generated, noise is reduced, and rolling resistance is reduced. Furthermore, even if a force S in the tire width direction or circumferential direction is applied to the block 4 during cornering and braking as shown in FIG. Since it can contact M and receive the force S, the steering stability is improved and uneven wear is reduced. In contrast, in a conventional tire having a block-based tread pattern as shown in FIGS. 8 and 9, when the tire rotates in the direction of rotation shown by arrow T as shown in FIG. Since it contacts the road surface M suddenly, the noise becomes louder and the rolling resistance increases.

Then, as shown in FIG. 7(A), when braking, the block 4
When a force S in the tire width direction or circumferential direction is applied to the tire, only the narrow portion of the edge portion 6 contacts the road surface M and receives the force S, as shown in FIG. 7(B). ,
Steering stability deteriorates and uneven wear increases.

Examples are shown below.

〔Example〕

The following noise levels were evaluated for the tires of the present invention and conventional tires when they were new. The results are shown in FIG. 5. Also, rolling resistance, difference in wear amount within one block, and steering stability were evaluated. The results are shown in Table 1.

(1) Tire of the present invention.

Tire size 205/60 R15゜Figures 1 and 2
It has a block-based tread pattern as shown in the figure. Chamfer angle α = 156° Chamfer depth h = 1°0LIIla
, All blocks of the tread are chamfered.

(2) Conventional tires.

Tire size 205/60 R15゜Figures 8 and 9
It has a block-based tread pattern as shown in the figure.

i'' level toy method The tires of the present invention and the conventional tires were installed on the front wheels of a domestically produced FR car, and the indoor car body noise was measured every 2000 km (measurement speed 80 km).
km/h) and evaluated based on the relationship between travel distance and sound pressure level. The results are shown in FIG.

In FIG. 5, a represents a conventional tire, and b represents a tire of the present invention. From FIG. 5, it can be seen that the sound pressure level of the tire of the present invention significantly decreases from the time of new to the early stage of wear.

- Kuno: The rolling resistance value when new was measured using an indoor rolling resistance tester. This result is expressed as an index.

The larger the number, the better.

The evaluation was made by measuring the difference in the amount of wear after traveling 6,000 km on a general road at an average speed of 30 km/h during one professional race.

1 - Based on the usual feeling evaluation method. The larger the number, the better.

(Margins below this page) From Table 1 above, it can be seen that the tires of the present invention are excellent in rolling resistance, uneven wear resistance, and handling stability.

〔Effect of the invention〕

As explained above, according to the present invention, the edge portion of at least the block formed on the tire tread is chamfered over almost the entire circumference of the block, and the chamfer angle is set to 5° to 3011 with respect to the tread. It is possible to reduce noise (from when new to the initial stage of wear) and rolling resistance, and further improve handling stability and uneven wear resistance.

[Brief explanation of the drawing]

Fig. 1 is a plan view explanatory diagram showing an example of the trend pattern of the pneumatic tire of the present invention, Fig. 2 is an enlarged sectional view taken along line B-B, and Fig. 3 is a ground contact situation during rotation of the pneumatic tire of the present invention. FIGS. 4(A) and 4(B) are explanatory diagrams showing how force is applied in the width direction to the pneumatic tire of the present invention, and FIG. 5 is a diagram showing the relationship between travel distance and sound pressure level. It is. FIG. 6 is an explanatory diagram showing the ground contact situation during rotation of a conventional pneumatic tire, and FIGS. 7 (A) and (B) are explanatory diagrams each showing the degree of force applied in the width direction to the conventional pneumatic tire. FIG. 8 is an explanatory plan view showing an example of a trend pattern of a conventional pneumatic tire, and FIG. 9 is an enlarged sectional view taken along line A-A. 1... Tread surface, 2... Main groove, 3... Minor groove, 4...
Block, 5... side of the block. Figure Figure 2 Figure Figure Figure Figure

Claims (1)

[Claims] In a pneumatic tire having a block-based tread pattern on the tire tread surface, at least the edge portion of the block is chamfered over almost the entire circumference of the block, and the chamfer angle is set at 5° to 30° with respect to the tread surface. Features pneumatic tires.