JPH04173407A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To enhance braking/driving performance at the time of straight traveling, and at the same time to enhance cornering performance by providing a wave-shaped kerf extending in the width direction of a tire to respective blocks in the tread part, and also by changing the line connecting the central points of the amplitude of the wave-shaped kerf to the direction of the tire. CONSTITUTION:On a tread surface 1, a plurality of main grooves 2 arranged in the circumferential direction of a tire, and a plurality of lateral grooves 3 arranged in the width direction of the tire so as to cross to the respective main grooves 2 are provided, so that a large number of blocks 4 partitioned by these grooves are formed. In this case, to each block 4, one wave-shaped kerf 5 having a secondary wave form of a small amplitude d extending in the width direction of the tire is provided. And the line L connecting the central points of the small amplitude d is curved with a large amplitude D in the circumferential direction of the tire so as to describe a primary wave form. Thus, the length or density of the kerf 5 per block can be increased for enhancing the braking/driving performance at the time of straight traveling, and at the same time the ratio of kerf component in the circumferential direction of the tire can be increased for increasing the resistance to side skid, so that cornering performance can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire having a block pattern that improves braking and driving performance on snowy and icy roads as well as improving turning performance during cornering.

[Conventional technology]

In general, winter pneumatic tires have a block pattern with a linear kerf formed in the width direction of the tire, and the edge effect of the block itself and the kerf provides braking when driving straight on snowy and icy roads. - Driving performance (hereinafter referred to as braking/driving performance) is provided. However, since this tire only has a linear kerf formed in the width direction of the tire, although it provides good braking and driving performance when driving straight, when cornering on snowy and icy roads, the edge effect against sideslip does not work, so the turning performance is poor. It did not substantially contribute to cornering performance (hereinafter referred to as cornering performance).

Therefore, in order to improve such cornering performance, a tire with a zigzag kerf shape has been proposed. In particular, Japanese Patent Application Laid-open No. 62-241710 discloses that in order to further improve cornering performance, the kerf of the block located in the central region of the trend part is formed in a zigzag shape in the width direction of the tire, while the block located in a part of the shoulder A pneumatic tire has been proposed in which a kerf is formed in a zigzag shape in the circumferential direction of the tire. However, although this pneumatic tire improves cornering performance by increasing the kerf component in the tire circumferential direction, there is a problem in that braking and driving performance deteriorates due to a decrease in the kerf component in the width direction of the tire.

[Problem to be solved by the invention]

An object of the present invention is to provide a pneumatic tire that has improved braking and driving performance during straight running and at the same time improved cornering performance.

[Means to solve the problem]

The pneumatic tire of the present invention that achieves these objectives is:
In tires with many blocks in the tread,
The block is characterized in that at least one corrugated kerf extending in the tire width direction is provided, and a line connecting the center point of the amplitude of the undulating kerf is formed so as to change in the tire circumferential direction.

In this way, the shape of the kerf to be formed on the block can be changed to a waveform (
(hereinafter referred to as a secondary waveform), and the line connecting the center point of the amplitude was made to change in the tire circumferential direction (hereinafter referred to as a secondary waveform).
- order waveform), the kerf component in the circumferential direction of the tire increases and the lateral resistance increases, so cornering performance increases. In addition, the component of the kerf in the tire width direction does not decrease, and the overall length or density of the kerf increases, thereby making it possible to improve braking and driving performance when traveling straight.

Hereinafter, the present invention will be specifically described with reference to the drawings.

FIG. 1 shows an embodiment of the tire of the present invention, and is a conceptual diagram showing a part of the tread pattern of the tire at a half width from the tread development width (TDW) center C. As shown in the figure, a tread surface 1 is provided with a plurality of main grooves 2 in the tire circumferential direction and a plurality of lateral grooves 3 in the tire width direction that intersect with these main grooves 2, and a large number of blocks 4 divided into these. is formed. These blocks 4 form five rows of blocks arranged in the circumferential direction of the tire.

Each block 4 is provided with one waveform curve 5 having a secondary waveform with a small amplitude d extending in the tire width direction, and furthermore, a line connecting the center point of the small amplitude d has a large amplitude in the tire circumferential direction. It is curved and depicts a primary waveform.

By forming the waveform kerf having a secondary waveform to draw a primary waveform in this way, the length or density of the kerf per block can be increased, which improves braking and driving performance when traveling straight. At the same time, the ratio of the kerf component in the circumferential direction of the tire can be increased, increasing resistance to side slips and improving cornering performance.

In the present invention, the shape of the secondary waveform of the waveform curve is
It is not limited to a sine wave as shown in the figure and Fig. 2, but may be a triangular wave as shown in Fig. 3, or various shapes such as other semicircular waves. can.

Further, the -th order waveform may be curved as shown in FIGS. 1 and 3, or may be refracted as shown in FIG. 2.

In order to increase the edge effect, it is desirable that both ends of the corrugated kerf communicate with the sides of the block 4 as much as possible, as shown in FIGS. 1, 2, and 3. good. In addition, the wavelength and period length of this waveform curve can be arbitrary, but in order to increase the edge effect while maintaining optimal block rigidity, the wavelength of the curve provided per block should be the same, and the blocks should be arranged It is desirable that the wavelength of the block from the center of the tread to a part of the shoulder becomes shorter depending on the position of the tread.

Further, it is desirable that the number of waveform curves formed in each block is changed depending on the size of the block, its arrangement, or the shape, wavelength, amplitude, etc. of the waveform curve formed on each block. Further, it is preferable that the depth of the corrugated kerf is equal to or shallower than the groove depth of the lateral groove.

In addition, the size of the block is changed randomly in order to reduce pattern noise with respect to the length l in the tire circumferential direction, but with respect to the width W in the tire width direction, all blocks are made substantially the same, or the tread It is desirable that the thickness of the block be gradually increased toward the block located closer to the shoulder than the center. The shape of the block is not limited to the rectangular shape as shown in FIG. 1, but can be any shape.

In the embodiment shown in FIG. 1, the shape and dimensions of the corrugated kerf formed in each block and the size of the kerf component in the tire circumferential direction are all the same, but they may be made to be different for each block. In particular, from the point of view of improving cornering performance, since the ground pressure of a part of the shoulder greatly contributes, it is preferable to form the amplitude of the -order waveform so that the kerf of the block located on the part of the shoulder side becomes larger. Further, since the circumferential component of the waveform kerf can be increased by increasing the amplitude d of the secondary waveform, it is preferable to increase the amplitude d of the waveform kerf of the block located on a part of the shoulder.

Furthermore, in the present invention, it is not necessarily necessary to provide the above-mentioned waveform curve having a secondary waveform with an amplitude d and a primary waveform with an amplitude of It is also possible to create a curve with only secondary waveforms.

〔Example〕

The following three types of tires of the present invention, Comparative Tire I and Comparative Tire ■ were manufactured.

The size of these tires is the same 1000
It was set to R20.

Tire of the present invention: - Tread pattern: block pattern shown in Figure 1 - Tread development width (TDW): 215 mm - Block size: l = 25 mm, w = 35 mm
・Groove width: main groove 2 = 10 mm, lateral groove 3 = 10 mm ・Amplitude of kerf: d = 5 mm, D = 10 mm Comparison Tire I: The corrugated kerf is only a secondary waveform and does not form a -order waveform (amplitude A tire that was the same as the tire I of the present invention except for D=0).

Comparison Tire ■: A tire that was the same as Comparison Tire ■, except that the direction of the wave-shaped kerf of some blocks on the shoulder was made to extend in the tire circumferential direction.

When these three types of tires were subjected to the following braking test and turning test on ice floes, the results shown in the table were obtained.

■Dynamic wiping: A test tire was attached to the drive wheel of a test vehicle, and the braking distance was measured when braking on an ice floe from a speed of 30 km/hr.
Evaluation was made using the reciprocal number. The braking performance was expressed as an index in which the reciprocal of the measured value of the comparative tire 1 was taken as 100. The larger the index value, the better the braking performance.

One plate scissors: Attach a test tire to the drive wheel of a test vehicle, and set a radius of 30m.
The time required to make one revolution on the circle of the water basin at the limit speed without skidding was measured, and the evaluation was made by the reciprocal of the time. The cornering performance was expressed as an index in which the reciprocal of the measured value of the comparative tire (2) was taken as 100.

The larger the index value, the better the cornering performance.

From the table above, the tire of the present invention has significantly improved braking performance and cornering performance compared to comparative tire (2). On the other hand, Comparative Tire ■ has improved cornering performance compared to Comparative Tire I, but has lower braking performance compared to Comparative Tire I.

〔Effect of the invention〕

According to the present invention, in a tire in which a large number of blocks are provided in the tread portion, a waveform kerf provided on the block so as to extend in the width direction of the tire is arranged such that a line connecting the center point of the amplitude of the waveform curve extends in the tire width direction. Since the tire is changed so as to draw a waveform, the proportion of the kerf component in the circumferential direction of the tire increases, thereby increasing the lateral resistance force and improving the cornering performance in snowy waterways. Furthermore, since the total length or density of the kerf is increased, braking and driving performance when traveling straight on a snowy road can be improved.

[Brief explanation of drawings]

FIG. 1 is a conceptual plan view showing a part of the tread pattern of the tire of the present invention with respect to the half width with respect to the center of the tread width;
FIGS. 2 and 3 are conceptual plan views showing examples of other block patterns of the tire of the present invention with respect to the half width corresponding to FIG. 1, respectively. 1...Trend surface, 4...Block, 5...Curf. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] In tires with many blocks in the tread,
A pneumatic tire, wherein the block is provided with at least one corrugated kerf extending in the width direction of the tire, and the line connecting the center points of the amplitudes of the undulating kerf changes in the circumferential direction of the tire.