JP2000043507A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress pattern noises and reduce the striking sounds from block elements without enlarging the variable ratio and without use of too many pitch numbers. SOLUTION: The surface of a tread part 1 is furnished with tread patterns including longitudinal rows of block groups A, B, C, D, E formed from many block elements 4 partitioned by circumferential grooves 2 stretching in the tire circumferential direction and crosswise grooves 3 intersecting the grooves 2. The block groups A, B, C, D, E are configured with repetitive arrangement pattern of block elements 4 having three sorts of pitch, a small pitch S, medium pitch M and large pitch L, and arrangement patterns of block elements 4 having different pitch differ from row to row of these block groups A, B, C, D, E.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire suitably used as a heavy duty tire, and more particularly to a reduction in tire noise.

[0002]

2. Description of the Related Art Tire noise includes vibration noise generated by resonance of an exciting force (unevenness of road surface, discontinuity of pattern, etc.) to a running tire at a natural frequency of the tire itself, and also a tread. A striking sound that hits the road surface when the surface touches the ground, and a pattern noise (pumping noise) that occurs when air compressed between the tread surface and the road surface that has touched the ground flows out of the tread contact surface through a groove in the tread surface. ) Etc. are known.

[0003] Each of these sounds appears remarkably in the primary component of the frequency determined by the pitch number and the rotation speed of the tire, and often has a large level peak, which affects the tire noise. Conventionally, many measures have been conceived and implemented to reduce the level of this primary peak. That is, since these noises can be reduced in noise level by a tread pattern designing method, various proposals have conventionally been made (Japanese Patent Application Laid-Open Nos. Hei 7-156614, Japanese Patent No. 2665931, and Japanese Patent No. 2665932). Gazette,
Japanese Patent No. 2665933, JP-A-7-156615
And JP-A-4-262905).

[0004] For example, JP-A-7-156614,
Japanese Patent No. 2665931, Japanese Patent No. 2665932, Japanese Patent No. 2665933 and Japanese Patent Laid-Open No. 7-1
No. 56615 discloses that a block element having many types of circumferential lengths (pitch lengths) on a tread surface is arranged in the same row in the tire circumferential direction to form each column block group. It discloses a pitch variation of a so-called variable arrangement that reduces the noise level by dispersing the primary component to a number of other frequencies.

The invention disclosed in Japanese Patent Application Laid-Open No. 4-262905, in addition to the arrangement method described above, has a structure in which a horizontal groove adjacent to a block element having a large pitch length is reduced, and a horizontal groove adjacent to a block element having a small pitch length is enlarged. By averaging the pitch length, the impact force on the road surface due to the block element having a large pitch length is reduced, and the impact sound is reduced.

[0006]

The noise reduction effect by these pitch variable techniques is more effective as the variable ratio of the block elements is larger, that is, as the difference in pitch length between the block elements is larger. It is considered that the more random the arrangement of the block elements, the more effective.

[0007] However, in the prior art, if the variable ratio is increased, the difference in rigidity between the block elements arranged in the tire circumferential direction becomes large, which causes uneven wear of the block elements, which is not preferable.

Further, in order to effectively reduce noise by randomly arranging the block elements, it is necessary to use an unnecessarily large number of pitches, which complicates the tread pattern and makes the molding of the mold complicated. It is not preferable because the cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pitch variation capable of suppressing pattern noise and reducing the impact sound of a block element without increasing the variable ratio and using an unnecessarily large number of pitches. Another aspect of the present invention is to provide a pneumatic tire having:

[0010]

As a result of diligent studies to solve the above problems, the present invention is defined on the surface of a tire tread portion by a circumferential groove extending in the tire circumferential direction and a transverse groove crossing the circumferential groove. In a pneumatic tire in which a tread pattern including a column block group including a large number of block elements is arranged, the column block group includes:
It is composed of a pattern arranged by repeating a plurality of types of block elements having different pitch lengths, and at least one of the above-mentioned column block groups is arranged in a different arrangement method from the other column block groups. A pneumatic tire characterized by a certain feature was adopted.

Therefore, the pneumatic tire according to the present invention is composed of a group of tandem blocks arranged by repeating a plurality of types of block elements having different pitch lengths. A single frequency determined by the number of pitches can be distributed to many different frequencies to reduce pattern noise.

Moreover, in the pneumatic tire of the present invention, at least one of the above-mentioned tandem block groups has block elements arranged in a different arrangement method from the other tandem block groups. A so-called variable pitch arrangement appears between each of the column blocks. The variable pitch arrangement between the column block groups is compared with the case where the block elements are arranged in the same arrangement pattern in each column block group in a variable manner.
The frequency of the above-described pattern noise is more effectively dispersed to random frequencies, so that an effect of so-called white noise is provided.

Therefore, in the case of the pneumatic tire of the present invention,
Tire noise can be reduced without increasing the variable ratio of the block elements constituting the tandem block group and without using an unnecessarily large number of pitch numbers.

Further, when the block elements are arranged in the same arrangement pattern in each column block group in a variable manner, it is possible to prevent adjacent block elements in the tire width direction from hitting the road surface at one time during running. Each column block group needs to have a phase in the same direction, but since the vibration waveforms generated from each column block group are the same and do not change, the frequency dispersion effect by the phase cannot be expected. As in the tire of the present invention, when the block elements are arranged in a variable manner even between the tandem block groups, at the time of traveling, the impact of each row on the road surface is a random impact, not only a reduction due to the dispersion of the primary component but also the impact. Vibration noise can also be reduced.

In particular, the tire noise during coasting is mainly due to the impact vibration of the block element hitting the road surface, that is, the contribution of the primary component is large. When the block elements are arranged in a variable manner, the effects of the dispersion of the primary component of the pattern noise, that is, the so-called white noise, and the reduction of the striking vibration sound due to the same effect as the phase shift of the block elements appear particularly remarkably. .

In view of the above, a tire having a plurality of types of block elements having different pitch lengths arranged in each column of the vertical block group, that is, a different array pattern in all the vertical block groups, is most preferable.

However, the area that greatly contributes to noise generation is
Since it is a shoulder region including a shoulder contact edge in the width direction of the tread, even if the pneumatic tire has an arrangement of block elements constituting each column block group of this shoulder region different from each other or from the center region. Thus, it is possible to sufficiently reduce tire noise.

Each tandem block group is composed of at least two kinds of block elements having the same kind of pitch length in order to form a so-called variable arrangement pattern. In the case of the tire of the present invention, two to four kinds of pitch elements are used. Only by forming each column block group with long block elements, it is possible to sufficiently reduce the pattern noise and the striking vibration sound.

[0019]

FIG. 1 is a schematic view showing a tread pattern showing one embodiment of a pneumatic tire according to the present invention.

In FIG. 1, 1 is a tread portion, 2 is a circumferential groove provided on the surface of the tread portion 1 and extends in the tire circumferential direction, and 3 is a transverse groove crossing the circumferential groove 2. 4 is a block element defined by the circumferential groove 2 and the lateral groove 3.

The tire according to the present embodiment includes a large number of block elements 4 in a shoulder area SA on the surface of the tread portion 1 and a center area CA located between the shoulder areas SA.
Are arranged in the form of column blocks A, B, C, D and E, respectively. The vertical block groups A and E are vertical block groups located in each shoulder area SA, and the vertical block groups B, C and D are three vertical block groups located in the center area CA.

The block elements constituting the cascade block groups A, B, C, D, and E have three types of pitches, a small pitch S, an intermediate pitch M, and a large pitch L, depending on the type of pitch length that is the circumference. It is composed of an array pattern arranged by repeating block elements having a length. Note that SE indicates a Schulder ground end.

As shown in FIG. 1, M-S-L-M-L-M-S-M-L is used as a repetition unit in the column group A of the shoulder area SA, and M-M-L is set in the column block group E of the shoulder area SA. SSMLMLML is used as a repeating unit. The column block group C located on the tire center line TC in the center area CA is L-L-M-S-
S-S-M-L is a repetition unit, and the vertical block group B of the center area CA located on both sides thereof is M-L-M-L.
M-L-M-S-S-S, the column block group D is M-M-M-
MSMML is used as a repeating unit. Therefore, in the pneumatic tire of the present embodiment, each of the column blocks A, B, C, D, and E has the block elements 4 arranged in a different arrangement from the other column blocks. still,
It is not always necessary to form the repeating unit, and a plurality of blocks having different lengths may be repeatedly arranged on the circumference of the tire.

FIGS. 2 to 4 are schematic views showing tread patterns showing an example of a conventional pneumatic tire. Both tires, like the tire of the embodiment of the present invention,
Block elements having three types of pitch lengths of a small pitch S, an intermediate pitch M and a large pitch L are arranged in repetition. However, in the case of the tire shown in FIG. 2, each of the column block groups A, B, C, D, and E has M as shown in Table 1.
SSMMLML + MSMLMSML + MLMMMLMSS
+ LLMSSSML + MMMMMSMML + MSSMML
ML + MSMLMSML + LLMSSSML are composed of block elements 6 having the same arrangement without a phase difference and having three different pitch lengths. In FIGS. 2 to 4, TC is the tire center line, S
E indicates a Schulder ground end.

FIG. 3 shows a case where a phase is further added to the arrangement method of FIG. 2 and is conventionally used as a technique for reducing the impact sound. That is, in the case of the tire shown in FIG. 3, each of the column block groups A, B, C, D, and E has MSSMMMML + MSMLM as shown in Table 1.
SML + MLMMMLMSS + LLMSSSSML + MMM
MSMML + MSSMMLML + MSMLMSML + L
The LMSSSML is constituted by block elements 6 having three types of different pitch lengths each having a pitch arrangement and a phase difference between each column being 1/4 pitch.

In the case of the tire shown in FIG. 4, each of the column blocks A, B, C, D, and E has an equal pitch length of the intermediate pitch M, and the phase difference between the columns is 1/4 pitch. It is composed of block elements 6.

In FIGS. 2 to 4, reference numeral 7 denotes a circumferential groove;
Is a horizontal groove. The column blocks A and E are column blocks located in each shoulder area SA, and the column blocks B, C and D are three column blocks located in the center area CA.

In the case of the conventional pneumatic tire shown in FIG. 2 and FIG. 3, the block elements 6 having three types of pitch lengths of a small pitch S, an intermediate pitch M and a large pitch L are arranged in a repeated manner. Since the block group is configured, a single frequency determined by the peripheral speed of the tire, the pitch number of the block element on the tire circumference, and the tire rotation speed, that is, the primary component and its harmonic components are dispersed at many different frequencies. Thus, the pattern noise is reduced. Further, by providing a phase as in the case of FIG. 3, the impact sound is further reduced.

On the other hand, also in the case of the tire of this embodiment, block elements 4 having three kinds of pitch lengths, that is, a small pitch S, an intermediate pitch M and a large pitch L, are arranged repeatedly to form a tandem block group. Therefore, a single frequency determined by the peripheral speed of the tire, the number of pitches of the block elements on the circumference of the tire, and the number of rotations of the tire, that is, the primary component and its harmonics are dispersed at many different frequencies, and the pattern noise is reduced. .

However, unlike the conventional tire, the tire according to the present embodiment has a different pitch arrangement among the respective vertical block groups A, B, C, D, and E in addition to the above-described effects. Since the frequency of the pattern noise can be more effectively dispersed to random frequencies, the levels of the primary component and its harmonic components are reduced, and the pattern noise is reduced.

In the conventional tire shown in FIG. 2, the block elements are arranged in the same arrangement pattern in each column block group in a variable manner, so that the adjacent block elements 6 in the tire width direction have a small pitch. Intermediate pitch M for each S
Hit the road at once for each child or large pitch L.
In order to prevent this phenomenon, a phase is generally provided between each column block row as shown in FIG.

On the other hand, in the case of the tire of the present embodiment, during running, the impact on the road surface is a so-called random impact in which the small pitch S, the intermediate pitch M, and the large pitch L are impacted separately, and a phase is provided. As in the case, the vibration noise due to the impact is reduced. However, in the method of providing a phase as in the related art, the frequency dispersion effect of the first and higher harmonic components due to the phase cannot be expected. Therefore, the present invention is superior to the reduction of the pattern noise in terms of the frequency dispersion effect.

[0033]

EXAMPLES Pneumatic tires according to Examples and Comparative Examples shown in Table 1 were prototyped, and tire noise was evaluated. Table 1 shows the contents of the evaluation tire according to the example. For comparison, the same comparative tire was trial-produced except that the arrangement of the block elements was different as shown in Table 1 and similarly the bench noise level was evaluated. Air pressure of each tire is 700
KPa / 2725 kg was set. The bench noise level is
The test was performed according to JASO-C606, and the noise level at each speed was measured.

[0034]

[Table 1]

FIG. 5 is a graph showing the relationship between the vehicle speed and the on-board noise level. The thick solid line graph shows the example tire, and the dotted line, the one-dot chain line and the two-dot chain line show the comparative tire.

As shown in FIG. 5, in the example tire, the vehicle speed was 20 k
m / h to 120 km / h
The noise level is reduced due to the dispersion effect of the next component and the reduction of the striking force, and a remarkable reduction effect is shown at a vehicle speed of 100 km / h which coincides with one of the natural frequencies of the tire.

[0037]

According to the tire of the present invention, the vertical block group is constituted by repeatedly arranging a plurality of types of block elements having different pitch lengths, and at least one of the vertical block groups. The group is
Furthermore, since it is a pneumatic tire in which block elements are arranged in a different arrangement method from other column block groups, a so-called variable pitch arrangement appears in each column block group, and also between each column block group. As a result of the so-called variable pitch arrangement, the primary and harmonic components determined by the tire rotation speed and the pitch number, which greatly contribute to the pattern noise, are dispersed in frequency to many random frequencies, so-called white noise. To

Furthermore, since the block elements are arranged so as to give a variable phase as a result between the cascade block groups, the impact on the road surface becomes random during traveling, and the exciting force is reduced. Vibration noise can be reduced (impact excitation force reduction effect).

Therefore, the pneumatic tire of the present invention can provide the above-described white noise and shock excitation without increasing the variable ratio unlike conventional tires and without using an unnecessarily large number of pitches. Tire noise reduction can be achieved as a synergistic effect of the force reduction effect.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a tread pattern showing one embodiment of a pneumatic tire according to the present invention.

FIG. 2 is a schematic view showing a tread pattern showing an example of a conventional pneumatic tire.

FIG. 3 is a schematic view showing a tread pattern showing an example of a conventional pneumatic tire.

FIG. 4 is a schematic view showing a tread pattern showing an example of a conventional pneumatic tire.

FIG. 5 is a graph showing a relationship between a vehicle speed and a bench noise level.

[Description of Signs] 1 Tread portion 2 Circumferential groove 3 Horizontal groove 4 Block element A Column block group B Column block group C Column block group D Column block group E Column block group S Small pitch M Intermediate pitch L Large pitch SA Shoulder area CA Center area

Claims (5)

[Claims] 1. A tread pattern including, on a surface of a tire tread portion, a tread pattern including a group of tandem blocks composed of a plurality of block elements defined by a circumferential groove extending in a tire circumferential direction and a transverse groove crossing the circumferential groove. In the pneumatic tire, the tandem block group is constituted by a pattern arranged by repeating a plurality of types of block elements having different pitch lengths, and at least one tandem block group among the tandem block groups. Is a pneumatic tire, wherein the arrangement method is different from that of other tandem block groups. 2. The pneumatic tire according to claim 1, wherein arrangements of a plurality of types of block elements having different pitch lengths are different from each other in each column of the tandem block group. 3. The pneumatic tire according to claim 1, wherein the arrangement of the block elements constituting each column block group in the shoulder region including the tire shoulder ground contact end is different from each other. 4. The pneumatic tire according to claim 1, wherein each of the tandem block groups is composed of block elements having a plurality of pitch lengths of the same type. 5. The pneumatic tire according to claim 4, wherein each of the tandem block groups is constituted by block elements having two to four kinds of pitch lengths.