JPS6060011A - Low noise tire - Google Patents

Abstract

PURPOSE:To make it possible to effect white-noise, in a tire having less than 45 total pitch number of patterns, by laying basic pitch groups of patterns in the order of their lengthes, and as well by arranging the patterns over the entire periphery of the tire with the use of one cycle having a specific arrangement as a basic pattern. CONSTITUTION:The total pitch number of tire pattern is set less than 45, and estimating that the lengthes of (m) kinds of basic pitches are l1, l2,...lm (l1< l2...<lm) in the order of their lengthes, the following relation is satisfied, 1<ln/ ln-1<=1.08 (n=2,...m). Further, lm/l1<=1.8. Further estimating that groups having suitable number of arranged basic pitches are L1, L2...Lm, and the one in which these group Ln is arranged such as L1, L2, L3,...Lm-1, Lm, Lm-1,...L3, L2, L1 is taken as one cycle, the entire periphery is constituted by two cycles. With this arrangement, the realization of white noise may be made possible, and as well uneven abrasion may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a tread pattern for a low-noise tire.

In order to reduce normal pattern pitch noise, pitch noise is dispersed by arranging basic pitches of different lengths appropriately around the entire tire circumference.

However, in order to make the pitch sound more similar to white noise, it is necessary to increase the difference in the length of the basic pinch.

However, if basic pinch elements with extremely different lengths are made in succession, the trend stiffness will suddenly change, the wear will not be uniform, or the vibration performance will deteriorate.

Conventionally, in order to prevent performance from deteriorating, the following restrictions have been placed on the arrangement of basic pinches.

That is, be sure to arrange basic pitches of the same length or basic pitches that differ in length by one step on both sides. −
4 For example, when the basic pitch is set to β1.12, -111, 1m in order of shortest length (j! l < 1
'l <------- (when there is a relationship A m), there are 7 on both sides of a certain basic pinch element ln! n-1,
j! n, I! Although pinch elements of either n+l were arranged side by side, even with the above method, vibration performance, uneven wear, etc. could not be solved, and white noise production was also insufficient.

This invention was made with the aim of solving the above-mentioned conventional drawbacks, achieving white noise, and completing a tire pattern with good vibration performance and less uneven wear.

The low noise tire according to this invention is (1) The total number of pinches must be 45 or less.

(2) The lengths of the m types of basic pinches that make up the pattern, in order of length, are 121, It 2, ------1
2 m (111 <7!2------<
l m ) β n 1〈□≦1.08 (n-2, --------m )2
n-1, and 2m□≦1.8.

It/ (3) Each L is an appropriate number of each basic pitch.
l, L2, ------1 to m.

Ln is one or more basic pitch elements of length ln lined up. These Ln are Ll , L2 , L3
, ------- Lm-1, Lm, Lm-1, ---
---When L3 and L2 are lined up as one cycle, the entire circumference of the tire is composed of two cycles, but three conditions are provided.

According to frequency modulation theory, in order to disperse the pinch sound, it is desirable to have the same pinch in succession, and in order to suppress the difference in tread stiffness due to the difference in pitch length, it is desirable to make the pitch length change as much as possible. need to be reduced.

That is, arrange the groups of basic pinches in order of length and perform the above (3)
) It is desirable to arrange them all around the tire on a one-round basis.

That is, the question is how many cycles should be used to make up the entire circumference.

The inventors succeeded in determining the optimal number of cycles using the calculation method described below.The total number of pinches is N, and the pinch lengths of the three basic types are arranged in descending order of Ill.
, 12, β3, (1 <β2<13> The number of each basic pitch element is 7! Number of 1 = N/4 Number of β2 - N/2 Number of 13 - N/4, basic pitch element length The difference in the dispersion of the pitch sound depending on the number of periods was calculated using the ratio of zl z3 p = 1 - - □ = - - 1 as parameters 12 12 N and P.

Generally, when the total number of pitches is N, the pitch sound becomes louder when the harmonic order component is an integral multiple of N.

This is called the primary and secondary pitch.

The first-order component of the pinch has the largest value, and the contribution of the pinch sound is the largest.

The primary component of this pitch, that is, the maximum value at N=1 to 1.5N, was used as the score for the dispersion of the pinch arrangement during calculation. .

If this maximum value is written as MAX (Hn), MAX (
The smaller the value of Hn), the better the degree of dispersion of the pinch sound.

Figure 1 shows the above conditions, that is, 3 with N and P as parameters.
It is calculated using the difference between MAX (Hn) in the period and MAX (Hn) in the 2M period as an index.

On the graph, the area above the boundary line indicates that a period number of 3 has good dispersion, and the area below the boundary line indicates that a period number of 2 has good dispersion.

Particularly, the area surrounded by the broken line where the total number of pitches is 45 or less has a great advantage of having a period number of 2.

As described above, the above-mentioned (11(21+31) of this invention was established.

Next, in order to confirm the effect of the present invention, tire size 194
/70 HR70 was used to hand cut the sample, and the noise was measured using an indoor drum.

The pitch length and pinch arrangement of the present invention product and comparative (conventional) product are shown in Table 1 using the pattern shown in FIG. (Next page) Figure 3 shows the results of frequency analysis of the measured sound. The upper part of Figure 3 shows the frequency analysis results of the sound outside the car, and the lower part of Figure 3 shows the passenger seat inside the car, with a microphone above the seat. This is the result of frequency analysis of the measured sound.

The tire according to the present invention was found to have lower pitch primary and secondary components for both external and internal sounds, and the effect of noise reduction is clear.

Note that the measurement of the harmonic components described above is based on the following method. (Simulation Shiloh y method) Give a pulse of unit height to each pinch of the block pattern shown in the upper part of Figure 4, and replace it with the pulse shown in the lower part. This is predicted by Fourier transform of the pulse train.

The harmonic component is Table 1 continued Calculate by

That is, Hn: harmonic n-order component CO: normalization constant Wk: Pulse weighting is constant L: Tire - circumference length K second kth pulse N: Total number of pitches Let the absolute number of Hn be the value of each harmonic component.

This invention was completed based on the above-mentioned calculation results and experimental results, and prevents uneven wear, deterioration of vibration performance, etc., and achieves low noise.

[Brief explanation of drawings]

Figure 1 shows three periods of MAX (Hn) and three periods of MAX (H) using the total number of pinches N and pitch ratio P as parameters.
It is a figure which plots the difference of n) as an index. ■ indicates a region with good dispersion in three cycles; ■ indicates a region with good dispersion in three cycles; and ■ indicates a region of the present invention. FIG. 2 is a pattern diagram of the basic elements shown in Table 1. FIG. 3 is a diagram plotting the frequency analysis results of the measured sounds outside the vehicle (top) and inside the vehicle (bottom). FIG. 4 (upper) is a block pattern diagram, and (lower) is a pulse conversion diagram of the same. Patent Applicant: Sumitomo Rubber Industries, Ltd. No. 1 Pitch Piece 45J, N Fig. 3 Car 9F Ordinary 195/70HR14 ・Invented product person inside the car Kazuo Sugi Patent application 2 filed on September 12, 1980, name of the invention Low-noise tire 3, relationship with the case of the person making the amendment Patent applicant 4, agent Address: 542 Telephone (06) 262-0. 50
0 Address Junkei Building, 2-2-28 Minamisenba, Minami-ku, Osaka Name
Patent Attorney (8290) Ogawa - Omi Table 1 continued

Claims (1)

[Claims] In a tire pattern in which the total number of pitches is 45 or less, the basic pitch lengths of the mm types that make up the pattern are expressed in descending order of length as J l , A 2 , -- −−−−−−1 am, then (pl ρ2−−−−−−−−< It m )
n 1〈□≦1.08 (n = 2.−−−−−−−−−
=m)n-1 and 12m□≦1.8, 1 Furthermore, each LL is an appropriate number of basic pitches lined up.
SL2,-------1Lm, and these Ln are Ll, L2, L3-------1L
m 1 , Lm, Lm −1, -----------
1L3. A low-noise tire characterized in that the entire circumference is made up of two cycles, when the line arranged as 1, 2, Ll is referred to as a -cycle.