JPH05608A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the acoustic tone-quality of pattern noise by providing linear or zigzag main grooves in the circumferential direction, forming plural number of ribs conforming to specified conditions in a tread ground contact area under a JIS standard internal pressure, load, and making the types of arrangements of pitch elements plural. CONSTITUTION:Linear main grooves 2 are provided on the tread surface T in the circumferential direction EE', and ribs 3, 4, 5 whose maximum depth are formed in a tread ground contact area W1 under a JIS standard internal pressure, load. Further, sub-grooves 6, 6' are provided across the tire width on the ribs 3, 4 at uneven intervals along the circumferential direction. Thus, blocks 7 partitioned by the sub-grooves are arranged as pitch elements in a specified order, and at least two types of arrangements are obtained. As a result, the acoustic tone-quality of patter noise can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire in which the audible quality of noise (pattern noise) generated between a road surface and a tire due to rolling is improved.

[0002]

2. Description of the Related Art Conventionally, in order to reduce pattern noise, the size of pitch elements forming a tread pattern is set to two or more, and the time interval of pulse noise caused by these pitch elements is changed to make a specific noise. I tried to prevent noise from concentrating on the frequency band. This is based on the frequency modulation theory and is a method of dispersing the order component of the pattern noise over a wide frequency band to generate white noise. However, although this method can reduce the noise level of pattern noise, it may result in an unpleasant sound quality such as "smoothness" in terms of sound quality in terms of hearing, so this method is not always desirable. It was

Further, in Japanese Patent Laid-Open No. 1-282006, as a means for solving this sound quality defect, the pitch arrangement on the same rib is made equal, and the number of pitches is changed for each rib. It has been proposed to configure the noise generated from each rib with a pitch number ratio in consideration of musical tonality. However, in this method, the difference in rigidity of the pitch elements between the ribs becomes large, which may cause uneven wear.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to prevent such pattern noise from causing an unpleasant sound quality, and is a pneumatic tire with improved auditory sound quality of pattern noise. The purpose is to provide.

[0005]

Means for Solving the Problems The pneumatic tire of the present invention has a straight or zigzag-shaped main groove in the tire circumferential direction to provide 2 to 8 tires in the tread contact area under JIS standard internal pressure and JIS standard load. The ribs of which the maximum rib width is within 1.5 times the minimum rib width, and these ribs have a plurality of pitch elements with different circumferential lengths. Are arranged by repeating several cycles on the tire circumference with one pitch element group in which the lengths in the circumferential direction are arranged one by one in order from the longest to the shortest and from the shortest to the longest, and arranged in such a manner. In the pitch element group that constitutes each period, it is permissible to add or omit only one pitch element having the maximum or minimum circumferential length of part or all of the element groups for each rib. And each Sequence of pitch elements on the tire circumferential in Bed (hereinafter, sequentially referred sequence) is characterized in that the condition is satisfied sequence as described in at least two or more of the following.

The conditions referred to here are, among ribs having different arrangements of pitch elements on the tire circumference, the number of types of pitch elements, the number of cycles and the total number of pitch elements in one rib are i, n and m, respectively. The number of types of pitch elements, the number of cycles, and the total number of pitch elements in the other rib are j,
Assuming t and A, i, j, n, t, m and A are natural numbers, i and j are 5 or more, n and t are 4 or more, m and A are not equal, and m ± l · n (L = 0, 1, 2, 3) and A ± k
-It means that t (k = 0, 1, 2, 3) is not equal.

Here, the pitch element means an element forming a pitch arrangement, for example, a block divided by widthwise grooves on each rib. Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory plan view showing an example of a tread pattern of a pneumatic tire of the present invention. In FIG. 1, four linear main grooves 2 are symmetrically provided in the tire circumferential direction EE ′ around the tire equatorial line 1 in the tire tread surface T, so that under the JIS standard internal pressure and JIS standard load of the tire. Five ribs 3, 4, 5, 4, 3 are formed in the tread contact area (contact width W ₁ ) in FIG. The main groove 2 may have a zigzag shape. Further, in the tread ground contact area indicated by the ground contact width W ₁ , ribs are formed within a range of 2 to 8 ribs.

The width of these ribs is within 1.5 times the maximum width of these ribs and the minimum width. this is,
This is because when the ratio of the rib width of each rib is large, the difference in rigidity between the ribs becomes large and the uneven wear resistance is particularly deteriorated. In this embodiment, sub-grooves 6 and 6'in the width direction are provided on the ribs 3 and 4 at different intervals in the circumferential direction.
The blocks 7 divided by 6'are arranged as one pitch element in a predetermined order with reference to the length in the tire circumferential direction as described later. The ribs 3 are arranged as shown in Table 1, and the ribs 4 are arranged as shown in Table 2. That is, the rib 3 is sequentially arranged with the total number of pitch elements 72 on the tire circumference, the number of kinds of pitch elements 6 and the number of cycles 6, and the rib 4 is arranged with the total number of pitch elements 63 on the tire circumference and the pitch elements. The number of types is 5 and the number of cycles is 6 in this order. Here, in order to satisfy the theoretical background of the present invention described later by adjusting the relationship between the total number of pitch elements on the tire circumference, the number of types of pitch elements, and the number of cycles, the tire circumferential direction length in some cycles is Only one minimum pitch element is added.

FIG. 2 shows another example of the tread pattern of the pneumatic tire of the present invention. Five linear main grooves 2 are provided in the tire circumferential direction EE 'on the tread surface T of this embodiment, whereby the tread contact area (contact width W ₁ ) under the JIS standard internal pressure and JIS standard load of the tire. Six ribs 10, 11, 12, 13, 14, and 15 are formed on the. Further, in this embodiment, each rib except the rib 13 is provided with a sub-groove 16 in the tire width direction, whereby a plurality of blocks 17 having different circumferential lengths are formed on each rib.
The ribs 10 and 15 have the sequence shown in Table 1, the ribs 11 and 14 have the sequence shown in Table 2, and the rib 12 has the sequence shown in Table 3.
The sequential arrangements shown in are respectively applied. In the sequential arrangement shown in Table 3, the pitch element having the minimum tire circumferential length in some cycles is omitted for the same reason as that shown in Table 2.

In the present invention, the rib arrangement of each rib is made of at least two different arrangements for the following reason. That is, a time series variation due to tire rolling in an array consisting of the number of types of pitch elements i, the number of cycles n, and the total number of pitch elements on the tire circumference (total number of pitches) m is m ± h · n (h The result is that there is a peak in the order of (integer). When such an arrangement is used on the entire tread, the impression of "smoothness" is reduced in terms of sound quality because the intervals of the orders in which the peaks are present are wide, but the sound quality is pure tone and is rather audible. Therefore, in the present invention, in order to compensate for such a drawback, two or more arrays having a plurality of peaks of which the orders do not overlap are arranged on different ribs to narrow the interval of the orders having the peaks, The frequency component was apparently brought close to white noise to avoid a pure tone quality. This will be described in detail with reference to FIGS. 3, 4, and 5.

FIG. 3 shows the number of types of pitch elements i, the number of periods n,
The relationship between the order and the amplitude when the time series variation due to the rolling of the sequential array (1) with the total pitch number m is expanded into the Fourier series is shown. FIG. 4 shows the relationship between the order and the amplitude when the time series variation due to the rolling of the sequential array (2) with the number j of pitch elements, the number t of cycles, and the total number of pitches A is expanded into a Fourier series. Figure 5
Is a superposition of FIG. 3 and FIG. It can be seen that in FIG. 3 and FIG. 4, the intervals of the orders having peaks are wide, whereas in FIG. 5, the intervals are narrow and the noise is closer to white noise.

That is, according to the present invention, it is necessary to satisfy the following relationship in order to prevent the orders of generating peaks from overlapping between two different sequential arrays. The number of types of pitch elements, the number of cycles and the total number of pitch elements in one rib are i, n and m, and the number of types of pitch elements, the number of cycles and the total number of pitch elements in the other rib are j, t and A. Where i, j, n, t, m and A are natural numbers, i and j are 5 or more, and n and t are 4 or more,
m and A are not equal, and m ± l · n (l = 0, 1, 2,
3) and A ± k · t (k = 0, 1, 2, 3) are not equal. In this way, by defining the number of types of pitch elements, the number of cycles, and the total number of pitch elements, it is possible to effectively shift the order in which peaks are generated, and the sound pressure level of pattern noise is greatly changed. It is possible to improve the sound quality of pattern noise without the need. Here, when i and j are 4 or less or n and t are 3 or less, the result of the Fourier series expansion is not sufficiently concentrated and dispersed, which is one of the causes of "sawazawa" sound quality. It is not possible to obtain a sufficient sound quality improvement effect that is the object of the invention.

[0013] Note) Total number of pitch elements on the tire circumference: 72. Number of cycles: 6 cycles. Pitch element types: 6 types, A>B>C>D>E> F.

[0014] Note) Total number of pitch elements on the tire circumference: 63. Number of cycles: 6 cycles. Pitch element types: 5 types, A>B>C>D> E.

[0015] Note) Total number of pitch elements on the tire circumference: 68. Number of cycles: 6 cycles. Pitch element types: 6 types, A>B>C>D>E> F.

[0016]

[Examples] The following tires 1 and 2 of the present invention and comparative tires 1 and 2 having the same tire structure and tire size 195/65 R15 were manufactured, and the noise level and sensory evaluation of the sound quality of these tires were performed. . These results for comparison tire 2
Is shown as an index in FIGS. 7 and 8. The higher the number, the better.

The tire 1 of the present invention. It has the tread pattern of FIG. The rib 3 has the arrangement shown in Table 1, and the rib 4 has the arrangement shown in Table 2 on the tire circumference. The width of each rib and the circumferential length of each pitch element including the groove in the width direction are as follows. Width of rib 3 = 26 mm Width of rib 4 = 20 mm Width of rib 5 = 20 mm Circumferential length of each pitch element on the rib 3: Pitch element A = 33.70 mm Pitch element B = 31.00 mm Pitch element C = 28 .80 mm Pitch element D = 26.20 mm Pitch element E = 24.30 mm Pitch element F = 22.50 mm Circumferential length of each pitch element on the rib 4: Pitch element A = 38.80 mm Pitch element B = 35.20 mm Pitch element C = 31.50 mm Pitch element D = 28.70 mm Pitch element E = 25.85 mm

The tire 2 of the present invention. It has the tread pattern of FIG. The ribs 10 and 15 have the arrangement shown in Table 1, and the ribs 11 and 14 have the arrangement shown in Table 2.
Further, the ribs 12 are provided with the arrangements shown in Table 3, respectively. The width of each rib and the circumferential length of each pitch element are as follows. Width of rib 10 = 16 mm Width of rib 11 = 24 mm Width of rib 12 = 22 mm Width of rib 13 = 20 mm Width of rib 14 = 20 mm Width of rib 15 = 20 mm Circumferential length of each pitch element on ribs 10 and 15 Circumferential length of each pitch element on the same ribs 11 and 14 as the rib 3 of the present invention tire 1: Circumferential length of each pitch element on the same rib 12 as the rib 4 of the present invention tire 1: Pitch element A = 35.30 mm Pitch element B = 32.50 mm Pitch element C = 30.10 mm Pitch element D = 27.50 mm Pitch element E = 25.40 mm Pitch element F = 23.55 mm

Comparative tire 1. It has the tread pattern of FIG. In FIG. 6, as in FIG. 1, four linear main grooves 2 are symmetrically provided in the tire circumferential direction EE ′ around the tire equatorial line 1 on the tread surface T, whereby the JIS standard internal pressure is applied. And JI
S Five ribs 3, 4, 5, 4, 3 are formed in the tread contact area (contact width W ₁ ) under standard load. A plurality of blocks 7 are formed on the ribs 3 and 4 by the auxiliary groove 6 in the tire width direction.
Are formed, and the arrangement shown in Table 1 is provided on the tire circumference.

The width of each rib and the circumferential length of each pitch element are as follows. Width of the ribs 3, 4, 5: Same as the tire 1 of the present invention. Length of each pitch element on the ribs 3, 4 in the circumferential direction: Same as rib 3 of the tire 1 of the present invention.

Comparative tire 2. Although the pitch arrangement is different from that of the comparative tire 1, the tread pattern is the same. The ribs 3 and 4 are provided with a pitch arrangement according to the conventional idea shown in Table 4 on the tire circumference.
The circumferential length of each pitch element is as follows. Circumferential length of each pitch element on the ribs 3 and 4: Pitch element A = 32.10 mm Pitch element B = 27.50 mm Pitch element C = 24.40 mm

[0022] Note) The total number of pitch elements on the tire circumference: 72 Types of pitch elements: 3 types A>B> C. The noise level is evaluated by mounting tires on a domestic 2000cc FR vehicle (front engine rear wheel drive vehicle) and running it at a constant speed of 50km / h, and then measuring the noise level at the center of the passenger compartment. It depends. The sensory evaluation of the sound quality was based on the five-level evaluation by the feeling of three panelists who were on board when measuring the noise level. The results are shown in FIGS. 7 and 8. Table 5 shows the comments regarding the sound quality of each panel.

[0023] As can be seen from FIGS. 7 and 8 and Table 5, the tires 1 and 2 of the present invention are not so different in noise level from the comparative tires 1 and 2, but the evaluation point of the sound quality by sensory evaluation is high, and the sound quality is high. Has been improved. This is supported by comments on the sound quality of each panelist.

[0024]

As described above, according to the present invention, the straight or zigzag-shaped main groove is provided in the tire circumferential direction so that the tread contact area under the JIS standard internal pressure and JIS standard load of the tire is 2 Form ~ 8 ribs,
Of these rib widths, the maximum rib width is within a range of 1.5 times the minimum rib width, and at least two or more different pitch elements are arranged on the tire circumference in each rib. It is possible to improve the audible sound quality of pattern noise.

[Brief description of drawings]

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

FIG. 2 is an explanatory plan view showing an example of the tread pattern of the pneumatic tire of the present invention.

FIG. 3 is a relationship diagram between the order and the amplitude of a sequential array.

FIG. 4 is a relationship diagram between the order and the amplitude of a sequential array.

FIG. 5 is a relationship diagram between the order and the amplitude of a sequential array.

FIG. 6 is an explanatory plan view showing a tread pattern of a comparative tire.

FIG. 7 is an explanatory diagram showing noise levels of various tires.

FIG. 8 is an explanatory diagram showing a sensory evaluation of sound quality of various tires.

[Explanation of symbols]

1 tire equatorial line, 2 main grooves, 3 ribs, 4 ribs, 5
Ribs, 6 minor grooves, 7 blocks.

Claims (2)

[Claims] 1. A tire in which 2 to 8 ribs are formed in a tread contact area under JIS standard internal pressure and JIS standard load by providing straight or zigzag-shaped main grooves in the tire circumferential direction. The maximum rib width within the rib width is less than 1.5 times the minimum rib width, and these ribs have multiple pitch elements with different circumferential lengths from long circumferential lengths to short circumferential lengths. In the pitch element group which is arranged by repeating several cycles on the tire circumference, with one pitch element group arranged in order from the shortest one to the longest one as one cycle, and which constitutes each cycle so arranged. It is permissible to add or omit only one pitch element having a maximum or minimum pitch length in the circumferential direction of a part or all of the element groups for each rib, and to arrange the pitch of each rib on the tire circumference. Arrangement of elements A pneumatic tire characterized in that the rows are at least two or more different arrangements. 2. Among ribs having different arrangements of pitch elements on the tire circumference, the number of types of pitch elements, the number of cycles and the total number of pitch elements in one rib are i, n and m respectively, and the pitch in the other rib is When the number of element types, the number of cycles, and the total number of pitch elements are j, t, and A, respectively,
i, j, n, t, m and A are natural numbers, i and j are 5 or more, n and t are 4 or more, m and A are not equal, and m ± l ·
n (l = 0, 1, 2, 3) and A ± k · t (k = 0, 1,
The pneumatic tire according to claim 1, wherein (2, 3) are not equal to each other.