JPS6012318A - Low noise tyre - Google Patents

Abstract

PURPOSE:In plural main grooves made in the circumferential direction of tyre, to relieve the pattern noise effectively while to eliminate the shifted abrasion or vibration, by imposing special limitation on the ratio of the lengths of at least two pitch elements. CONSTITUTION:In a low noise tyre having two longitudinal grooves R-1, R-2 arranged in the circumferential direction of tread, when assuming the number of the pitch element of R-1 is n1, the order of length is L1<L2<L3...<Ln1, the number of the pitch element of R-2 is n2, the order of length is M1<M2<M3...<Mn2, the ratio of the length of pitch element of said grooves or Ln1-1=Pn1, (n1-1) and Mn2/Mn2-1=Qn2,(n2-1) will satisfy the conditions 1.05<=Pn1,(n-1)<=1.25 and 1.05<=Qn2,(n2-1)<=1.25 and exhibit excellent noise reduction effect when M1= P(n1+1),nn1Ln1,1<=P(n1+1),n1<1.3 and the difference between the maximum and minimum pitch ratio is lower than 0.15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to reducing the noise of a pneumatic tire in which the tread pattern (hereinafter referred to as the pattern) on the tire contact surface is a so-called rib pattern.

Tires with rib patterns, which are mainly used as tires for trucks, buses, and light trucks that run on good roads, must have excellent handling stability and high-speed durability. This type of lip type has a continuous pattern of contact with the ground, and unlike lug patterns designed mainly for use on unpaved roads, the four tones that accompany the atta are significantly advantageous.

However, in recent years, regulations regarding automobile noise have become more and more strict, and this vomiting noise is not only the sound of the engine, intake and exhaust system, and cooling fan, but also the sound of tires and scratching. Therefore, it is imperative to reduce the noise of the tires themselves, and it is now a major social need, and the tire industry as a whole must make efforts to reduce noise. .

Here, the noise caused by the tire V can be roughly classified according to its generation mechanism as follows.

41) Pattern Noise When the groove of the pattern comes into contact with the ground, the groove deforms and the air in the groove is compressed and discharged, causing the surrounding air to vibrate, causing a noise that causes 4 problems in the pattern pitch. A j-sound consisting mainly of scattered frequencies is generated.

+2) Elastic vibration noise Road unevenness, tire unevenness (tread rubber thickness,
Due to this (change in shape), periodic impact occurs with the road surface when the bicycle is rotated, and the tread and case vibrate, causing compressional waves in the outside air and noise.

6) Sliding and squeaking noise Sliding noise due to the movement of the tread within the contact surface of the tire, and squeaking noise caused by the tread becoming diamond-shaped before and after contact with the ground and causing partial slipping.

In general, tire noise is independent of the pattern type.
It is well known that the higher the speed of the car, the higher the noise level (although ribbed type cars have a relatively low level of noise, and the lug type cars have a relatively high level of noise level).

Most of the scratching noise is caused by filter 112), and at normal operating speeds of 80h/h or less (
It is known that 1) and 121 contribute approximately the same amount to 1).
Even if only one of the causes is eliminated, the effect of preventing delta noise is not sufficient. In order to prevent noise, the important performance of tires such as braking, driving, turning performance, maneuverability, and wear resistance must be improved. There is no point in bringing about inferior results in such aspects, and from the above-mentioned perspective, the present invention realizes particularly advantageous and low noise.

Conventionally, the first method to suppress this heel pattern noise is to divide the frequency of the noise into a wide frequency band t, and
In order to make the noise less noticeable and to prevent noise from increasing due to resonance with various parts of a stationary vehicle, the well-known barrier-pull pitch method improves the arrangement of pitch elements, which are the basis of repeated tread design. . This method involves appropriately arranging several types of pitch elements (pattern configuration pitches) with different pitch lengths in the circumferential direction of the tire, and eliminating the pattern noise or pattern noise generated during tire transfer. This is a method of changing vibration over time so that noise at a certain frequency is not concentrated, and is closely related to the so-called frequency modulation theory.

The second method is to reduce the tread radius of curvature of the tread contact surface to reduce impact noise with the road surface, and to reduce noise by making it easier to discharge air in the grooves.

All of the above-mentioned noise reduction methods are found to be effective at 4゛, but on the other hand, the method based on the frequency modulation theory of '(・1) has excellent dispersion of scratching noise. Even if the arrangement of pitch elements can be modified, for example, if the ratio of the length of the element with the longest pitch to the length of the element with the shortest pitch is large, the pattern rigidity of each pitch element will be affected. S.R.
It is unavoidable that the vibration becomes large, and this may have a negative effect on the vibration characteristics during tire transfer, and may cause uneven tread wear.
This does not progress, resulting in a tire with a very poor appearance due to so-called wear, which causes a significant reduction in tire life.

Furthermore, in the method (2) of reducing the tread radius of curvature, the ground contact pressure at the tread crown increases, causing premature wear of the crown, which significantly shortens the life of the tire. This results in a very uneconomical tire.

Therefore, the present invention maintains the tread curvature radius as large as before, and improves the tire circumferential direction without impairing wear and tear. Adding 1 arc to the 1,a number of main grooves provided here, especially to the ratio of the lengths of the two pitch elements, effectively reduces pattern noise. t
We have discovered a method that can solve problems such as flat wear and vibration that were problems of conventional 1-branch surgery.

To summarize the invention, in a rib-type tread pattern t in which the main grooves are two longitudinal grooves arranged circumferentially of the tread, one main groove t is arranged in a di pattern. The number of pitch elements is n, and the length order is Ll〈L2〈
L3<...<Lnl, C゛・Pinocheremenll& of one other main groove is N2. The length order is M + < M,
2 < M! 1<Pa...<M・N2, the ratio of pitch element lengths of these main grooves Ln1/Lnj-1
= Pnl + (ni-4) and Mn27MN2-1
= Qn2, (N2-9 are i, o5 < Pn, respectively)
l, (nl-+)≦1.25 and 1.05≦Qn2.

(N2-1) A pneumatic tire that satisfies the condition of <1.25 and is configured with two main grooves having alpitch elements arranged in the following range.

"'-P(shield 1)・HlLnj, + = pr, n
*+”)・°1〈′・6 The difference between the maximum and minimum pinch ratio is 0
．． Must be 15 or less.

In addition, in lip pattern tires e that have six or more vertical main grooves, two main grooves satisfy the above conditions, and the remaining main grooves are zigzag grooves or zigzag grooves with an arbitrary pitch arrangement. , and a pneumatic tire characterized by having straight grooves.

It goes without saying that the term "pneumatic tire" refers to all vehicle pneumatic tires having bias, radial, semi-miracial structures, etc.

However, what must be noted here is that when the number of pitches is Nj and N2 and N1>N2, considering the case where N+=MN2, the λ-th harmonic of the number of pitches N2 is the first-order harmonic of the pitch 1 fixed number N1. Match the ingredients. For example, in Figure 5, N2 electric pitch is 50, and N1 = 60.
) This shows the peak level of the first-order component of N1 when the pitch is changed to 140. At the point where N1 = IUO pitch, the second-order component of N2 and the first-order component of Nj overlap, the peak becomes higher, and the pitch increases. This shows that there are places where the noise is worse at the edge of the surface, and it is necessary to exclude places in the arrangement of pitch elements that meet the above conditions.

Now converting the pitch length into a pulse train, CO: normalization constant l: length of one circumference of the tire xk: th pulse position IJ: number of pulses n: integer harmonic two component first order component is pitch number N The second-order component of the two-dimensional harmonic component of n = N is the sharp noise of n = 2N.

The present invention will be explained below using the drawings. FIG. 1 shows a cross-sectional shape of a tire having a pattern of four longitudinal grooves as main grooves.

In the figure, 1 is a tread, 2 is a part of the tread/l/7', 6 is a tread crown @ 14R is a main groove of a vertical groove provided in the circumferential direction of the tread, 5 is a casing, and 6 is a belt layer. The radius of curvature of the tread contact plane is TB, and the tread width TV is the distance from the tread surface to the surface of the tread. , FIG. 2, and FIG. 3 show the pattern of the tread contact surface as an embodiment of the present invention. FIG. 2 shows a tread pattern with five main grooves, among which R-1 and R-2 are A pair of grooves having a relationship t that satisfies the condition of the ratio of pitch element lengths is shown, the remaining groove R-3 is a straight groove, and a tread pattern having five types of groove shapes is shown. Figure 6 is 4
The main groove of the book is a slanted pattern, and the two grooves R-1 and R-2 represent a pair of grooves that satisfy the condition of the ratio of pinch element lengths. The tread pattern is shown with two symmetrically arranged tread patterns (
R-1 = E-3, E-2-R-4), of course, the grooves E-3 and B-4 may be grooves having a pitch ratio that does not satisfy the pitch element length ratio condition. (R-
1') R-53R-2 R-4).

Below, the results of noise measurements are shown in FIG. 6, FIG. 7, and FIG. 8 based on an example of the present invention and a comparative example based on the prior art. The main specifications of the tires used in this test are shown in Table 1, and the test strip 1 cow is as follows.

Tire size near, (10-158PR.

Internal pressure: 6.25mm 9f/d or 2.40mm f/d.

How many layers: 550 air7 tires, 100 + from the center of the tire width with the collecting microphone right next to the tire? /11 gap, installed at a height of 25 t:m from the ground contact surface, measured while driving the tire by rotating a drum in an anechoic chamber (conforms to the tire noise test method specified in 5ASO0606)
.

As shown in FIGS. 6 and 7, the test results show that the product of the present invention has an excellent effect of reducing scree noise at any speed e.

From Table 1, the present inventor conducted a comparative test to see if there were any negative effects on tire performance, ie, wear resistance, handling stability, high-speed durability, etc., due to the above-mentioned reduction effect. The test results are shown in Table 2. The numbers in the table represent the values when the conventional product is taken as 100 as an index, and for any characteristic value, the higher the value, the better. .

Table 2 Uami test results eThe detailed explanation is as follows.

1] Steering stability for both front and rear wheels 7. OQ-'15 8PH tires are stuck, internal pressure is 2.4 k4/'' front + 3°25 rear
-/d, an actual vehicle feeling test (stability, maneuverability) was conducted by 6 people using Test Drino (-), and the results were compiled using a 6-point rating method.

2) High speed durability and internal pressure 4. 2 5 season/d, cargo port 98 0 kl/
Under tire conditions, straight 61. Start at a speed of 80 m/h on a steel drum with a smooth surface and run smoothly for 60 minutes, then increase the speed by 10 m/h and run for 30 minutes each. The vehicle was then evaluated based on the speed at which the tire failed.

As stated above, tires based on the present invention provide performance that is no inferior to conventional products in terms of zero handling stability, tree abrasion resistance, and high-speed durability. While doing so,
However, the embodiments of this invention are not limited to embodiments 61, 31!: 2, and 5 of this invention, and are based on the gist of this invention. Needless to say, various implementations can be devised.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the tire showing various parts of the tire, and FIG. 2 is a developed view of a pattern having six grooves showing one embodiment of the present invention.
Fig. 4 is a developed diagram of a pattern having four grooves showing one embodiment of the present invention, and Fig. 5 shows the primary order of the N1 groove when the N2 groove is 50 pitches and the pitch of the N1 groove is varied from 60 to 140. Indicates the peak level of the component. 6, 7, and 8 show the measurement results of the noise levels of the conventional product and the product of the present invention. 1... Tread, 2... Cill/L/Der,
3...Tread contact surface, 4R...Vertical groove, 6...Carcass part,... Belt part, R-1, R-2, R-5
, 1-4 are longitudinal grooves according to the embodiment of the present invention. Patent applicant: Sumitomo Rubber Hooporo Co., Ltd. Figure 1 Figure 2 Figure 311 Figure 5 Many! 1. Indication of the case 1982 Patent Application No. 119666 2. Name of the invention Low-noise tire 3. Person making the amendment Relationship to the case Patent applicant October 25, 1988 (shipment date) 5. Amendment Object ``/%=P/\--, 7 rFigure 4 is a pattern development diagram of a comparative example tire having four conventional grooves,'' is inserted.

Claims (1)

[Claims] (7-tread) In a rib pattern tire whose main grooves are two longitudinal grooves arranged in the circumferential direction, one of the main grooves is
Multiple pitch elements (pattern constituent units) arranged in this way
Let the number of + pitch length be Ll'<L2<
B, 5...I+, 'n1, +Same as e, the number of elements arranged in the other main grooves is nL, and the pitch length order is M.
When n<M2〈M, il〈...〈”n2,
Pitch element length ratio pn1/pn1-1=Pnl
, (nl-1) and Mn2/M (n2-1
) ==Q1n2, (n2-1) are each 1.
, 05≦Pn1', (nl-1)≦1.25, and 1.
1. A pneumatic tire comprising two main grooves satisfying the condition 05≦Q1n21 (n2 j )≦1.25 and having pitch elements arranged in the following range e. M+ = P(n1+1)+ nl Lnll <
P(nt+1)+nl<1-5 The difference between the maximum and minimum pinch ratios is u, 15- or less. b2) Rib pattern tire with tread circumferentially arranged and having 7 or more longitudinal grooves as main grooves.In this case, 12 main S's satisfy the conditions stated in claim + ig 1. A pneumatic tire characterized in that the other main grooves have zigzag grooves or straight grooves with an arbitrary pitch arrangement.