JPS6175003A - Low noise tire - Google Patents

Abstract

PURPOSE:To aim at lowering noise from a tire, by providing such an arrangement that shoulder transverse grooves which are positioned outside of a vehicle when the tire is installed on the vehicle, and center transverse grooves are formed in the tire, being inclined with respect to reference lines parallel with the rotating axis of the tire, in a predetermined range. CONSTITUTION:Shoulder grooves 2M in the outer half of a tread section which is positioned outside of a vehicle, are inclined at an angle theta1 of 10-35 deg. with respect to a reference line A which is extended from the end TM of the tread, in parallel with the rotating axis of the tire while center transverse grooves 3M are inclined at an angle theta2 of -10--35 deg. with respect to a reference line B which is extended from a longitudinal groove G2, in parallel with the rotating axis of the tier. With this arrangement the discharge of air is made smooth and it is possible to reduce air pumping sound and impacting sound so that the tire may have low noise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-noise tire in which air pumping noise and impacting noise are reduced in a block pattern radial tire.

[Prior art]

In recent years, with the development of expressway networks, automobile noise during high-speed driving has come to be taken up as one of the pollution problems, and tire noise is particularly important as one of the important factors of automobile noise. The main causes of tire noise are as follows.

(a) Pattern Noise The spaces or cut grooves on the tread surface are deformed by contact with the ground, and their volume is rapidly reduced, thereby releasing or pumping air to the outside. On the other hand, when the space or cut groove is released from the grounded state, the volume increases rapidly and at this time air is sucked into the interior.

Periodic pumping of air into and out of such spaces or cut grooves generates continuous pressure waves, that is, sound energy, but a peak of sound energy appears at a frequency corresponding to the pattern pinch, and this becomes noise. .

(b) Resonant noise relates to the distribution and elastic properties of tires, which act to generate significantly increased vibrations at various speeds and driving conditions of the tire in a repetitive time sequence. Vibration is generated in each part of the tire in response to the applied vibration generation energy, and if the pattern pitch is arranged so that the peak vibration frequency of the tread pattern matches the resonance frequency of the tire, a resonance effect occurs and the sound increases. becomes.

(c) Vibration noise due to slipping This is the sound generated when the tread portion slips with the road surface at various parts of the ground contact area.

In order to reduce the factors that cause noise, for example, regarding pattern noise, the sound energy that appears at a specific frequency is dispersed over a wide frequency band to reduce noise, which is the basis for repeating tread designs. In this method, several types of pitch elements with different pinch lengths are appropriately combined and arranged in the circumferential direction of the tire, and the peaks of sound energy that are periodically generated when the tire rotates are shifted in time to create a phase difference. The purpose is to lower the peak value and is based on the so-called frequency modulation theory.

Attempts have also been made to reduce the resonance noise and noise caused by slippage by improving the structure of the tire, the material of the carcass and the bottom of the belt, the tread rubber composition, and the tread pattern.

[Problem that the invention seeks to solve]

The barrier pull pitch method described above causes a difference in rigidity between the pitch elements, which has a negative effect on vibration characteristics during tire rotation, and tread wear does not proceed uniformly, resulting in a shortened tire life. Also, this method does not reduce the sound energy itself, but only disperses it over a wide frequency range, and there is a limit to the reduction of noise.

The invention aims to reduce noise by reducing the sound energy itself instead of the conventional frequency dispersion method of sound energy, and aims to solve this problem by paying particular attention to the shape of the tread groove. .

[Means for solving problems]

- The present invention divides the tread portion into a shoulder portion and a center portion by a pair of left and right vertical main grooves extending in the circumferential direction of the tire, and a shoulder lateral groove is arranged in the shoulder portion that communicates from the longitudinal main groove to the tread end. , On the other hand, in the center part, a central lateral groove is arranged which communicates from the one longitudinal main groove or the central longitudinal groove attached to the center part so as to extend in the circumferential direction of the tire to the other adjacent longitudinal main groove or the center 1i14. In a tire with a block pattern, when the tire is mounted on a vehicle, the shoulder lateral grooves on the outer half of the tread portion located on the outside of the vehicle are aligned with reference line A extending from the tread end parallel to the axis of rotation. The angle θ1 is in the range of 10 to 35 degrees, while the angle θ2 of the central lateral groove is in the range of 10 to -35 degrees with respect to the reference line B extending from the longitudinal main groove parallel to the tire rotation axis. This is a low-noise tire.

An embodiment of the present invention will be described below based on the drawings.

In FIG. 1, the tread portion T has a pair of left and right longitudinal main grooves 0.
1. It is divided into shoulder part SR and central part CR by G2, and the width WSR of the shoulder part is the tread width TW.
is set in the range of 10% to 30%. In each of the shoulder portions SR, a shoulder lateral groove 2 (M
), 2 (N) are formed at regular intervals in the tire circumferential direction.

When the tire is installed on the vehicle, the outside corresponds to the left side of the figure, and the shoulder section on the outside of the vehicle is SR (M), the shoulder horizontal groove is 2 (M),! - The red end is designated as T (M). On the other hand, the inside of the vehicle corresponds to the right side of the diagram,
(N) is displayed after each display number.

In the central part CR, there is a central longitudinal groove GC that extends in the tire circumferential direction.
It is formed along both sides of the tire equatorial plane C, and divides the central portion CR into three. The center +M groove 3 (N) on the right side that communicates from the center longitudinal groove GCI to the main longitudinal groove Gl on the right side and the center lateral groove 3 (M) on the left side that communicates from the other center longitudinal groove GC2 to the main longitudinal groove G2 on the left side of the tire. They are formed at regular intervals in the circumferential direction, and both ends of the central portion are divided into blocks.

Here, the shoulder lateral groove 2 (M) of the outer half of the tread portion located on the outside of the vehicle is located at the tread end T (M).
The angle θ1 is in the range of 10 to 35 degrees with respect to a reference line extending parallel to the axis of rotation of the tire from G2, while the central lateral groove 3 (M) The angle θ2 with respect to B is in the range of -10 to -35 degrees.

The noise generation mechanisms of the shoulder lateral groove and the center lateral groove are different; shoulder lateral groove 2 (M) acts to discharge the compressed air inside 8 toward the tread end.
The central horizontal groove 3 (M) directs the compressed air inside the groove to the central part 1Gc.
In order to smoothly discharge these airs, the angle of the former is set to be positive and the angle of the latter is set to be negative. In addition, the noise decreases as the absolute value of the angle θ1 and G2 of the shoulder lateral groove 2 (M) and center lateral groove 3 (M) increases, but from the viewpoint of balancing the tread pattern rigidity and preventing uneven wear, the absolute value of the angle is If you make it too big, you can't do the second thing. Therefore, as mentioned above, the angle θ of the shoulder lateral groove 2 (M) and the central lateral groove 3 (M) is
1. The absolute value of G2 is set in the range of 10 degrees to 35 degrees.

In the present invention, only the tread pattern on the outside of the vehicle has been described, but it goes without saying that the shoulder lateral grooves and the center lateral groove on the outside and inside of the vehicle may be configured as described above.

For a radial tire with a tire size of 205/60R15 and a tread pattern shown in FIGS. 2 and 3, the internal pressure is 2.
A prototype with only a shoulder lateral groove and a center lateral groove was manufactured under the conditions of 0 kg/cta and a load of 400 kg, and the sound 7 energy was measured. Acoustic energy was measured in an anechoic chamber using the tire noise test method specified by JASOC606.
The sound-collecting microphone was placed directly next to the tire, from the center of the tire width, and at a height of 15-15 cm from the ground plane in 50 countries.

FIG. 4 shows the sound pressure waveform of the tread pattern with only shoulder lateral grooves shown in FIG. 2.

The figure shows that the sound pressure is high when the ground is released. On the other hand, in FIG. 5, which shows the sound pressure waveform of the tread pattern only at the center portion R shown in FIG. 3, it is recognized that the sound pressure increases at the start of contact with the ground. Therefore, the angles θ1 and G2 of the shoulder lateral groove and the center lateral groove were changed for the tread patterns shown in Figures 2 and 3, and the acoustic energy index was calculated based on the sound pressure waveform. Here, the sound 7 energy index (E) can be calculated from the sound pressure (P) using the following relational expression.

The measurement results are shown in FIGS. 6 and 7. From the figure, the acoustic energy index decreases as the absolute value of the angle of the shoulder lateral groove, central lateral groove θ1, and G2 increases, but the difference in the acoustic energy index between the positive angle and the negative angle is that the absolute value of the angle is 10 For shoulder transverse grooves, the acoustic energy index is noticeable in the range of 10° to 35° at positive angles, and for central lateral grooves, in the range of -10° to -35° at negative angles. It is clear that the difference is large and that a wide improvement can be expected. In addition, the absolute value of angle θ1 and G2 is 35
If it exceeds 0.0°, the acoustic energy index becomes small, but this is not preferable in terms of improving the rigidity balance, grip performance, and uneven wear resistance of the tread portion.

FIG. 8 shows another embodiment of the present invention. This embodiment is the same as the embodiment shown in FIG. 1 except that the area between the central longitudinal grooves GC3 and GC4 is divided into blocks by horizontal grooves 41.

The embodiment shown in Figure i9 is the central lateral groove 3 (M) in Figure 1.
, 3 (N) is omitted and a central lateral groove 51 is formed in the region sandwiched between the vertical mains iG5 and G6.

〔Effect of the invention〕

As described above, the present invention provides a tread pattern that includes shoulder lateral grooves that communicate from the longitudinal main grooves to the tread ends, and central lateral grooves that communicate between the longitudinal main grooves and the central longitudinal grooves or between the longitudinal main grooves. The outer shoulder lateral grooves are set at positive angles to a specific range with respect to the reference line parallel to the tire rotation axis, while the central lateral grooves are set at negative angles to a specific range, so that the compressed air inside the grooves can be smoothly discharged. It is possible to effectively suppress pumping noise and impacting noise.

[Brief explanation of drawings]

FIG. 1 is a partial front view of the tire tread portion of the present invention, and FIG.
Figures 3 and 3 are schematic diagrams of the tread pattern, Figures 4 and 5 are graphs of the sound pressure waveform during tire rotation, Figures 6 and 7 are the central lateral groove angle, shoulder groove angle, and acoustic energy index. Graphs showing the relationship in FIGS. 6 and 7 are other embodiments of the present invention. G1, G2, G3, G4, G5, G6・- Longitudinal main groove, GC
l, G C2-central longitudinal groove, 2 (M), 2 (N), 21 (
M), 21 (N)...-Shoulder horizontal groove, 3 (M), 3 (N), 31 (M), 3
1 (N)・-Central lateral groove, T (M), T (N)・-Tread end, CR・～
Center part, SR(M), SR(N)・-Shoulder part. Patent applicant Sumitomo Rubber Industries Co., Ltd. Patent attorney
Nae Mura Tadashi Figure 4 Figure 5 Figure 6 Cause Figure 7 Center square square ← 2) Shi 3 Lugu 14
Maru (LCIl) No. 8, No. 9, No. 1, Yuge, No. 8 Hosho (Spontaneous origination with the October 18, 1985 incident) Patent applicant address: 1-1-1-4, Tsutsui-cho, Chuo-ku, Kobe City, Agent 6. Subject of amendment (1) Column 7 of "Brief explanation of drawings" of the specification, Contents of amendment

Claims (1)

[Claims] (1) The tread portion is divided into a shoulder portion and a center portion by a pair of left and right vertical main grooves extending in the circumferential direction of the tire, and a shoulder lateral groove that communicates from the longitudinal main groove to the tread end is arranged in the shoulder portion. The central portion has a central horizontal groove that connects the one longitudinal main groove or the central longitudinal groove attached to the central portion so as to extend in the circumferential direction of the tire to the other adjacent longitudinal main groove or the central longitudinal groove. In the arranged block pattern tire, the shoulder lateral groove on the outer half of the tread portion located on the outer side of the vehicle when the tire is mounted on the vehicle is at an angle θ_1 with respect to the reference line A extending from the tread end parallel to the tire rotation axis. is 10
-35°, and the central lateral groove has an angle θ_2 of -10° to -35° with respect to a reference line B extending from the longitudinal main groove parallel to the tire rotation axis. noisy tires.