JPS60116511A - Low noise tire - Google Patents

Abstract

PURPOSE:To maintain various performance and lessen noise in a low noise tire having a block pattern made up of straight, longitudinal grooves by adjusting the shape of blocks, the number of pitch elements, pitch length etc. in central and side regions of the tire tread. CONSTITUTION:A central region CR consists of two rows of central blocks A and B, both of which are nearly a parallelogram, divided by central, lateral grooves G1 having inclination angle alpha of 15-40 deg. and a central, longitudinal groove 3. Each side regions SR consists of block C, which is nearly a parallelogram, divided by side region lateral grooves G2 whose inclination angle beta are 15-40 deg.. In the both central region CR and side region SR, three kinds of pitch elements, small (S), medium (M), and large (L), are combined in such a manner that the number of pitches n1 in the central region is larger than that n2 in the side region, and each pitch element length, Ps, Pm, and Pl satisfies an expression not given here. With this constitution, noise can be reduced without deteriorating eccentric wear resistance and wet grip performance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a tire with a block pattern having linear vertical grooves extending in the circumferential direction of the tire. By adjusting pitch length etc., various performances such as uneven wear resistance and wet grip performance are not compromised.
Related to low-noise tires that reduce noise.

Recently, with the development of the expressway network, tire treads have adopted a pattern suitable for driving at high speeds, especially a block pattern based on linear vertical grooves extending in the circumferential direction of the tire. The aim is to improve stability when turning and braking performance.

However, this type of block pattern inevitably results in increased noise during running. This is because in tires with a normal block pattern, the circumferential blocks formed on the tight tread are formed by continuous and repeating pitch elements, which are repeating units, in the circumferential direction. , compression waves are generated in the air by periodic compression and release of the air contained in the groove that occurs between the ground plane and the pulsed vibration of each pitch element or each of its multiple orders, and pattern noise is based on the so-called pumping sound. occurs. In order to reduce this pattern noise, it is known to disperse the pattern noise over a wide frequency range and adjust the pinch element in order to alleviate the yA sound. This allows for several types of jigs with different pinch lengths.
By forming Pisodico~Remen 1- using frequency components, the time interval of the pulse noise and vibration that occur during tie-1 transfer can be changed to prevent the sound from reaching a specific frequency. However, in general, the adoption of blocks with a pitch length of p promotes uneven wear.

Attempts have also been made to reduce noise by reducing the width and depth of the horizontal grooves that separate the blocks, but this results in a low F of wet grip and is not effective. .

The present invention proposes a low-noise tire that achieves low noise without sacrificing uneven wear or wet grip performance.

The low-noise tire of the present invention will be described in detail below according to examples.

FIG. 1 is a partial plan view of the tire of the present invention.

In 1, the tie-1-T of the present invention has a throat portion divided into a central region CR and a measuring region SR by two linear side vertical grooves 1.2 extending in the circumferential direction. Furthermore, the central region CR is divided into two by a straight central longitudinal groove 3 along the tire equatorial plane C.

The central region CR extends from one side longitudinal groove 1 to the other side longitudinal groove 2.
Two rows of central blocks Δ, B each having a substantially parallelogram shape are formed from substantially the same basic shape and are separated by a straight central lateral groove Gl that communicates with the center blocks. The area P (angle α) of this central lateral groove G1 relative to the tire circumferential direction must be in the range of 15° to 40°. If the angle is smaller than 15°, the block angle becomes an acute angle,
The uneven wear due to the decrease in the rigidity of the corners becomes severe, and on the other hand, 40
When exceeding °, the pumping sound becomes intense and
This is not preferable because the t-speed running characteristics are deteriorated.

In addition, in the present invention, in the circumferential center of each center block 1.1 1.
Arrange M g 1 and divide each of A and B into two to form A 1', A 2, B1, and B2, and set the grip to 1i i1'[i. ), but this narrow horizontal groove g1 does not necessarily require complete separation of block I-1 vines A and 13, and block element A
A configuration may be adopted in which block elements B1 and B2 are partially connected.

In the measurement S R of the tread portion, a measurement lateral groove G2 communicating from the side longitudinal groove 1.2 to both ends of the trend is arranged, and a block C having a basic shape of a substantially parallelogram is formed. There is. The inclination angle β of this measured lateral FIG2 with respect to the tire circumferential direction is 15° to 40°, and this is set from the viewpoint of adjusting uneven wear noise as in the case of the central lateral groove G1. It is assumed that angles α and β are not the same.

f (The figure shows that the left and right measurement transverse grooves are both inclined in the same direction, but the left and right slope angles may be set in opposite directions.In addition, each block C is
As with the center blocks A and B, it is possible to arrange a narrow lateral groove g2 approximately at the center in the tire circumferential direction, and to subdivide the block C into completely or partially separated block elements C1 and C2.

l]Wc in the central region is 20% to 50% of WT during the trend.
Preferably it is in the range of 28% to 38%.

In the present invention, both the central region CR and the measurement SR have different pitch lengths of 34il? ili's pinch niremen 1
-8 (element with a small pinch length), M (an element with an intermediate pitch length), and L (an element with a long pinch length), and the number of pitches n1 in the central area is a side block. The number of pitches is greater than 02.

The pattern noise during tire transfer is caused by the pumping sound that occurs periodically on the contact surface for each pitch element, but the sound caused by this pitch element is caused by the respective primary, secondary,
In sounds such as tertiary tones, a sharp peak occurs, resulting in a first meridional sound that is difficult to hear.

Therefore, in order to alleviate the occurrence of sharp peak sounds, the pitch lengths of the pitch elements are made different to disperse the peak sounds. fj/i is the central region, and (Ill
3 in both areas I! It is preferable that the lengths Ps, Pm, and p/ of the IE force 1 satisfy the following conditions.

0.8PM≦PS≦0. ! l P Ml, 1PM≦
P17≦1.2PM 3 types of pitch yew/Non 1~ length PS, PM.

This is because by limiting the mutual ratio of PL, it is necessary to reduce the variation in rigidity between blocks by (+11) and prevent uneven wear.

Furthermore, the number of pitches in the central area nl is the number of pitches in the side blocks n2
The reason for increasing the number is to make the dispersion of the peak sound between the center region and the measurement more effective. Similarly, central area C
Offset interval I of pitch elements of R and side mass SR,
It is preferable to make the pitch length PS smaller than the smallest pitch length PS in order to prevent the peak sound based on the off-cellar 1-spacing and the peak sound based on the pinch element from overlapping.

The side longitudinal grooves 1.2 and 11 need to be wide in order to maintain wet grip, while the center longitudinal grooves 3 are
It is not necessarily necessary to form a medium-wide groove, but rather it is not preferable because it reduces wear resistance.

Therefore, the groove tp W 3 of the central stepped groove 3 is formed smaller than the side longitudinal groove W1.

In addition, each pitch length PS, PM, P of pitch niremen 1- in the central region and side blocks! , is the circumferential length of the block and the central lateral groove 6 included in each pitch element l-3, M, and L.
1,'! W3S, W3M, W3L and (region cedar') in η
J i? l') G 2's nrli Ic W 4 s
, W4M, W4L by changing 5llJ Q'r
%), but it is usually set so that the following relationship holds true.

W 3 S < W 3 M < W 3 LW4s <
W4M<W4L saw W3S ≠ W4 S, W3M l-
W4M, W3 I-, W4L.

As shown in the description above, the present invention is a tire with a straight block pattern, and the block shape, pitch elements, number of pitches, etc. are fixed to rl.
By setting 4 constants, it was possible to achieve low noise without increasing the wet grip property (it + uneven wear) η to 471.

EXAMPLE Tires of tire size L'225/751-15 with tread patterns not shown in Figure 1 and tires of the comparative example shown in Figure 2 were prototyped, respectively, and the noise test I and wet grip properties were evaluated as 1.゛I do. The detailed specifications for n' of the prototype tire are shown in Table 1.

The noise test was conducted at an internal pressure of 2.4 Kgf/cnl. iiJ
Measurements were taken in an anechoic chamber under drum running conditions of 530 Kgf with a sound collecting microphone set at a distance of 100 cm from the center of the tire (t) and 25 cm above the ground contact surface.

(Compliant with tire noise test method specified by JASO, C60fi)
. The relationship between the noise level and the running speed is shown in Figure 3.

The tire of the present invention has a wide range of low dryness noise levels.

Wet grip performance was determined by measuring the coefficient of friction μ (when locked) between the tire and the road surface during actual Hayabusa driving on a 1fa wet road surface of a JA II I, and the relationship with the speed is shown in FIG.

From FIG. 4, it can be seen that the wet grip of the tire according to the present invention, shown by the solid line, is better than that of the comparative example tire.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view of the tire of the present invention, FIG. 2 1 is a partial plan view of a comparative tire, FIG. 3 is a graph showing the relationship between noise and speed, and FIG. 4 is a coefficient of friction l! It is a graph showing the relationship between speed and speed. 1.2-・Side longitudinal groove, 3-・Central line groove, CR・・Central area, 'SR-・Measurement, A, B, C-1・Block, G1-Central horizontal groove, (32- m = measured transverse groove, S, M,
1. , - Pisochelemen 1-1 ++ Lg2 - narrow transverse groove. Patent Applicant Sumitomo Rubber Industries Co., Ltd. Representative Patent Attorney Tom Naemura

Claims (1)

[Claims] 11) Tie 4 - The tread portion is divided into a central region CR and a measurement SR by two linear side longitudinal grooves 1.2 extending in the circumferential direction, and the central region CR is aligned with the tire equator. It is divided into two by a straight central longitudinal groove 3 along the plane C, and the central region OR and the measuring SR each have a block pattern separated into block groups by the central lateral groove G1 and the measuring lateral groove G2, respectively. , the angles α and β of the central lateral groove G1 and the measured lateral groove 02 with respect to the tire circumferential direction are in the range of 15° to 40°, and the central region CR and measured SR both have three different pinch lengths.
It is composed of pitch elements S (element with short pitch length), M (element with medium pitch length), ■ (element with 1a long pitch length), and the number of pitches in the center J13iCR is n1. A low-noise tire characterized by having a pitch number r12 greater than the pitch number r12 of the measurement S R. (2) Three types of pyu in central region CR and measurement SR
Pitch lengths PS, PM, PL of chelements S, M, L
The low noise tire according to claim 1, characterized in that: satisfies the following relationship: 0,8 PM M≦PS≦0.9PM 1.1PM≦PL51.2PM (3) The offset interval °C of the pitch elements of the central region CR and the measurement SR is characterized by being smaller than the smallest pitch length PS. A low-noise tire according to claim 1. (4) The low-noise tire according to claim 1, wherein the groove width Wc of the central longitudinal groove is smaller than the groove width Ws of the measured lateral groove.