JPH0429563B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention reduces running noise in a tire with a rib-type pattern having zigzag vertical grooves extending in the circumferential direction of the tire by selecting the pitch length, etc. of each element of the pattern constituent unit forming the vertical grooves. This invention relates to a low-noise tire that achieves In recent years, along with the demand for lower noise in automobiles, there has also been a desire to lower the rolling noise of tires. Generally, the circumferential vertical grooves formed on a tire tread are formed by continuously repeating pattern constituent units, which are repeating units of the groove pattern, in the circumferential direction. A so-called pumping sound is generated as a pattern noise based on compression waves of air due to periodic compression and release of the air contained in the grooves generated between the patterns, or pulsed vibrations of each pattern constituent unit or multiple orders thereof. In order to reduce this pattern noise, it is known to disperse the pattern noise over a wide frequency range and adjust the pattern constituent units in order to reduce the noise. By forming pattern units using zigzag components with several different pitch lengths, this method changes the time interval of pulse noise and vibration that occurs when tires roll, and changes the sound frequency to a specific frequency. It is intended to prevent concentration. For example, Japanese Patent Publication No. 58-22364 states that (a) the ratio of the maximum pitch element length to the minimum pitch element length is 1.2 or more and 1.6 or less; (b) The number of modes is 2 or more and 12 or less. (c) Three or more different pitch elements. Discloses a low-noise tire that meets the requirements. However, this proposed tire is based on the premise that the same pattern constituent unit is used repeatedly in each groove. Further, JP-A-58-26608 discloses a pattern unit having one main element and two subordinate elements, but the pattern unit is the same in each groove as in the previous one. Furthermore, although JP-A-58-78801 discloses that two grooves have different groove shapes, one groove is formed by repeating one type of main element of the same length. It is configured. The present invention was completed as a result of repeated research on pattern constituent units, and aims to provide a low-noise tire that can reduce noise while maintaining tire characteristics. The present invention provides a tire having a rib-type pattern having at least two zigzag longitudinal grooves extending in the circumferential direction on the tire tread surface, in which each of the longitudinal grooves has one main element M consisting of one chevron-shaped groove, and a main element A zigzag pattern constituent unit p that is joined with one to four subordinate elements S consisting of one chevron-shaped groove having a pitch length Rs in the circumferential direction smaller than a pitch length Rm which is the length in the circumferential direction of M. The pitch length Rm of the main element M of each pattern constituent unit p and the pattern constituent unit p
The ratio (Rs/Rm=rP) of each subordinate element S included in pitch length Rs is greater than 0.200 and 0.225
less than, greater than 0.275 and less than 0.308, 0.358
greater than and less than 0.475, greater than 0.525 and 0.642
, greater than 0.692 and less than 0.700, and the longitudinal groove is in the range of the main element M
consisting of two types of longitudinal grooves using pattern constituent units having different pitch length Rm and number of subordinate elements S, and the pitch length of the main element M in the pattern constituent unit p of the one type of vertical groove.
The ratio of Rmi to the pitch length Rmj of the main element M in the pattern constituent unit p of the other type of vertical groove (Rmi/
This is a low-noise tire characterized by having Rmj = rM (where Rmi > Rmj) greater than 1.10 and less than 2.60. In this way, the pitch length Rm of the main element M included in the pattern constituent unit p and each subordinate element S
Since the ratio (Rs/Rm=rP) to the pitch length Rs is set within the predetermined range, the frequency is dispersed and an increase in noise due to synchronization is suppressed. Moreover, since the vertical grooves are composed of two types of vertical grooves using pattern constituent units in which the pitch length Rm of the main element M and the number of subordinate elements S are different from each other, the frequencies can be distributed and synchronized even between the vertical grooves. This suppresses the increase in noise due to noise and makes it possible to reduce noise. Also, the pitch length ratio of the main element in the vertical groove pattern constituent units of one type and the vertical groove pattern constituent units of the other type (Rmi/Rmj=rM)
By setting the value to be larger than 1.1, noise dispersion becomes effective and the effect of adopting the composite longitudinal groove is enhanced. In addition, by setting the value to be smaller than 2.6, the difference in pitch length of the main element M is reduced. It is possible to prevent excessive wear, reduce the difference in pattern rigidity, and prevent uneven wear. Furthermore, the two types of longitudinal grooves described above improve the dispersion of peak levels due to harmonic components, effectively dispersing noise, and making it possible to reduce noise. It also improves vibration characteristics during tire rolling. In this way, the number of subordinate elements S of the two longitudinal grooves is different from each other, and the pitch length of the main element in the pattern constituent unit of one type of vertical groove and the pattern constituent unit of the other type of vertical groove is different from each other. By adopting a new configuration based on which the ratio of An embodiment of the present invention will be described below based on the drawings. FIG. 1 is a partial plan view of the tread surface of a low-noise tire 1 according to the present invention. It has a tread surface with a rib type pattern comprising G2, G2. It is also a good idea to provide siping, narrow grooves, etc. that do not significantly affect noise. The longitudinal grooves G2 are arranged on both sides of the tire equator C, and the longitudinal grooves G1 and G1 are arranged on the outer side of the tire equator C at approximately equal intervals. Each vertical groove G1, G2 has a pitch length Rm1, Rm
2 main elements M1, M2 (generally referred to as main elements M) and subordinate elements S1, S2 with shorter pitch lengths Rs1, Rs2, respectively.
It consists of repeating pattern constituent units p1 and p2 (generally referred to as pattern constituent units p) consisting of pattern constituent units p1 and p2 (generally referred to as subordinate elements S). In addition, pitch length Rm1, Rm2, pitch length
Rs1 and Rs2 are defined as the length in the tire circumferential direction. Further, the pattern constituent unit p1 of the vertical grooves G1 and G1 each has one main element M1 and one subordinate element S1,
Moreover, the pattern constituent unit p2 of the vertical groove G2 includes one main element M2, two subordinate elements S2 of the same shape,
S2, and the facing longitudinal grooves G1, G1 and G2, G2 are arranged point-symmetrically about a point on the tire equator C. Each of the main elements M1, M2 and the subordinate elements S1, S2 are connected to one groove extending in the circumferential direction at an angle with respect to the tire equatorial plane C, and are connected to this groove at approximately the same angle with respect to the tire equatorial plane C. Each chevron-shaped groove consists of a chevron-shaped bend consisting of another groove of the same length that slopes in the opposite direction. Therefore, the pattern constituent unit p in which the main element M and the subordinate element S are connected is formed in a zigzag shape. For those skilled in the art, the length of each pitch, the angle of inclination of the groove, etc. are determined depending on the desired performance of the tire. can be easily selected. The features of the present invention are, firstly, that each vertical groove G1, G
1, G2, and G2 are dispersed by adjusting the pattern constituent units p1 and p2. The pattern noise when a tire rolls is caused by the pumping sound that periodically occurs on the ground surface for each pattern component p, but the sound caused by this pattern component p is composed of each primary, secondary, tertiary, etc. Sharp peaks occur in the sound, resulting in harsh noise. Therefore, in order to alleviate the occurrence of sharp peak sounds, the pattern constituent unit p is divided into a main element M and a subordinate element S, and the pitch length of the main element M is set Rm.
1, Rm2 (generally referred to as pitch length Rm)
The pitch length ratio rP of the pitch lengths Rs1 and Rs2 (generally referred to as the pitch length Rs) of the slave element S, that is, rP=Rs/Rm, is set in the range of 0.200 to 0.700. In addition, the subordinate element S with pattern constituent unit p of 2 to 4
, the pitch length ratio rP of each of the pitch lengths Rs of each subordinate element S included in the pattern constituent unit p is set within the same range. The noise dispersion will first be explained using the vertical groove G1 shown enlarged in FIG. 2 as an example. As described above, the vertical groove G1 has pattern constituent units p1 each consisting of one main element M1 and one subordinate element S1. For such a pattern constituent unit p1, the noise level and the pitch length ratio rP1 (when specifying the vertical groove with respect to the pitch length ratio rP, the symbols 1, 2, etc. are given according to the code of the vertical groove G1..., and the general term We have found that the relationship between the pitch length ratio (rP) can be determined by computer simulation. This simulation has been found to correlate with real tires. As shown in FIG. 3, the noise level of the first to fifth sounds changes sinusoidally with the pitch length ratio rP1. Here, the pitch length ratio rP1 is 0,
That is, in the case of only the main element M1, the primary component becomes the main noise source. On the other hand, the pitch length ratio
When rP1 is 1, that is, when the pitch lengths Rm1 and Rs1 of the main element M1 and the subelement S1 are the same, the secondary component becomes the main noise source. Note that the pitch length ratio rP of the harmonic component sound that is the sum of the number of main elements M and the number of subordinate elements S is 1.
It becomes the main noise source when In the case of the tire with pattern constituent unit p1 in Figure 2, the sound of the secondary component is the most important, and the lowest range of the noise level of this component is the ratio of the pitch length.
rP1 is in the range of 0.200 to 0.700. Furthermore, in Fig. 3, the pitch length ratio rP1 of each order component from second to fifth order is 1/4, 1/
It is recognized that peak values are reached at positions 3, 1/2, and 2/3. This is due to the fact that the sounds produced by the main element M and the slave element S are synchronized. Note that the conditions for synchronization associated with computer simulation can be determined as follows. The length of the main element M1 and the slave element S1 in the axial direction of the tire, that is, the pitch height Hm
1, Hs1 is replaced with pulse trains U1 and U2 of equal strength, and harmonics analysis is performed using the following equation. Hn=Co _o 〓 ^k=1 Wk・ei2πn/LXk where Hn: n-th harmonic component Co: normalization constant Wk: pulse weighting constant L: total pitch length of pattern constituent unit k: Kth element (k = 1, the main element) n: Number of elements in the pattern constituent unit Rm: Pitch length of the main element Rs: Pitch length of the subordinate element Xk: Position of the pulse In the above, the main element M1 and the subordinate element S1 are synchronized. The condition for this is 2nπ (1-Rm/Rm+Rs) = 2jn, so rP=Rs/Rm=j/n-j (j<n) Here, the higher the order of pattern noise, the lower its contribution to noise. Let n≦5. Therefore, the pitch length ratio rP that satisfies n=1, 2, 3, 4, 5 and j<n and j/(n-j)<1
Find 1/4, 1/3, 1/2, 2/3 4
A column is found, which coincides with the peak position of the noise. Therefore, it is important to ensure that the pitch length ratio rP does not reach the above value, but furthermore, if the value of the pitch length ratio rP is higher than this peak position,
It is desirable and necessary that the pitch length ratio rP not be included within the 0.025 range below, and therefore the pitch length ratio rP is excluded from the following exclusion range N. 1/4-0.025≦N≦1/4+0.025 1/3-0.025≦N≦1/3+0.025 1/2-0.025≦N≦1/2+0.025 2/3-0.025≦N≦2/3+0 .025 In other words, the exclusion range N is 0.225 or more and 0.275 or less,
0.308 or more and 0.358 or less, 0.475 or more and 0.525 or less, 0.642 or more and 0.672 or less. From the above results, the pitch length ratio rP is greater than 0.200 and 0.700.
When combined with this exclusion range N, the pitch length ratio rP is greater than 0.200 and 0.225
less than, greater than 0.275 and less than 0.308, 0.358
greater than and less than 0.475, greater than 0.525 and 0.642
, greater than 0.692, and less than 0.700. Next, the vertical groove G2 will be explained. As described above, the vertical groove G2 is a pattern constituent unit p that is a combination of one main element M2 and two subordinate elements S2 and S2 of the same shape.
It has 2. The pitch length ratio of this vertical groove G2
Figure 5 shows the results of computer simulation of the relationship between rP2 and noise level. The vertical groove G2 is a combination of one main element M2 and two subordinate elements S2, and the total number of these elements is 3, that is, the 3rd order has the most influence on the noise.
It is recognized that the noise level of the third-order sound is also the lowest when the pitch length ratio rP2 is in the range of 0.200 to 0.700. Furthermore, Fig. 6 shows a pattern constituent unit p3 which is a combination of one main element M3 and three subordinate elements S3, S3, S3, and the ratio of the pitch length to this unit is shown.
Figure 7 shows the results of computer simulation analysis of the relationship between rP3 and noise level. Here, since the total number of the main element M3 and the subordinate element S3 is 4, the fourth-order sound has the greatest influence on the noise. The fourth order sound also has the lowest noise level with a pitch ratio rP in the range of 0.200 to 0.700. In the low-noise tire 1 of the present invention, the pattern constituent unit p includes 1 to 4 subordinate elements S, and the vertical groove G includes a pitch length Rm of the main element M and the number of subordinate elements S. consists of two types of vertical grooves using mutually different pattern constituent units, and in the case shown in FIG. 1, consists of vertical grooves G1 and G2. Note that the pattern constituent unit p3 shown in FIG. 6 can also be used as one of the vertical grooves. The low-noise tire 1 shown in FIG.
and the vertical groove G2 of the pattern constituent unit p2 shown in FIG.
In the case of a composite vertical groove G that combines vertical grooves G2, the ratio of the pitch lengths Rm1 and Rm2 of the main elements M1 and M2 of the vertical groove G1 and the vertical groove G2, respectively (rm
= Rm1/Rm2, however, if Rm2<Rm1)
It is set in the range of 1.10 to 2.60. In this way, in the present invention, in the two types of longitudinal grooves Gi and Gj of two different types of pattern constituent units p, the pitch length Rmi of the main element M of the pattern constituent unit p has a large length, and the pitch length Rmi of the main element M of the pattern constituent unit p has a small length. The ratio rM of the length of the main element M to the pitch length Rmj is set within the above range. When rM is smaller than 1.10, noise dispersion is not effective, and the effect of using compound vertical grooves cannot be expected. If rm exceeds 2.60, the difference in pitch length of the main elements M will become too large, resulting in a large difference in pattern rigidity, resulting in adverse effects such as uneven wear. In addition, the pitch heights Hm and Hs of each main element M and subordinate element S in the pattern constituent unit P, that is, the pitch heights Hm and Hs, which are the lengths between the two ends in the tire axial direction, are calculated by the ratio Hs/ The pitch height ratio rH, which is Hm, is in the range of 0.200 to 0.700. Note that when a pattern constituent unit p has 2 to 4 subordinate elements S, the pitch height ratio rH of each subordinate element S included in the pattern constituent unit p is set to the same range for each pitch height Hs. . By setting the pitch height ratio rH to a range approximately equal to the pitch length ratio rP, the heights of the main element M and the subordinate element S are made similar to the pitch length, and the vertical The inclination angles of the grooves G1 and G2 are made uniform. This is to reduce changes in pattern rigidity and prevent adverse effects on uneven wear, and also to prevent an increase in the noise level due to the increase in the inclination angle when the pitch height of the slave element increases. Furthermore, the low noise tire of the present invention is shown in FIGS.
As shown in the figure and as described above, the numbers of subordinate elements S are different in the two types of longitudinal grooves. In the case of FIG. 1, the vertical groove G1 is formed by a pattern unit p1 having one subordinate element S1, and the other vertical groove G2 is formed by a pattern unit p2 having two subordinate elements S2, S2. ing. In addition, in the case of Fig. 8, one type of vertical groove G2 is 2
pattern constituent unit p2 of two subordinate elements S2, S2
Accordingly, the other type of longitudinal groove G3 is a pattern unit p3 comprising three subordinate elements S3, S3, S3.
It is formed by. With such a simple configuration, the longitudinal grooves of different pattern constituent units p are combined in each tire, and the peak level dispersion state due to the harmonics component is improved, so that as shown in Figs. As shown, it has been found that noise can be effectively dispersed and noise can be reduced. In the low-noise tire 1 of the present invention, the vertical grooves are formed from pattern constituent units p4 and p5 including main elements M in the shape of a truncated mountain having a component parallel to the tire equator C, as shown in FIG. Alternatively, as shown in FIG. 19, a pattern constituent unit p6 including main elements M having different inclination angles on the left and right sides of the vertical groove G may be provided. Example 1 L/T tires with tire size 7.00-15.8PR,
Example product 1 whose tread design has longitudinal grooves G1 and G2 of each pattern constituent unit shown in FIG.
Vertical groove G of a pattern constituent unit p2 consisting of a main element M2 and two subordinate elements S2 and S2 shown in the figure.
2, G2, a pattern constituent unit p consisting of a main element M3 and three subordinate elements S3, S3, S3
Example product 2 according to the present invention in which vertical grooves G3 and G3 of 3 are provided, and main elements Ma and 1 shown in FIG.
Pattern constituent unit pa that repeats two subordinate elements Sa
A comparative example tire having four vertical grooves Ga... having the same shape was prototyped with the specifications shown in Table 1. Then, noise tests, wear resistance, and handling stability were evaluated. Regarding wear resistance and handling stability, Table 1 shows the noise test.
Figure 13 shows the frequency dependence of those noise levels. FIG. 11 shows a comparative example product, FIG. 12 shows an example product 1, and FIG. 13 shows an example product 2. It is recognized that both Example products 1 and 2 are significantly improved in terms of noise level reduction and sound dispersion. The test values in the table are expressed as an index with the value of the comparative example set as 100, and for any characteristic value, the larger the value, the better. The test conditions for the handling stability, wear resistance, and noise tests are as follows. (1) Driving stability For front and rear tires with 7.00-15.8 PR, internal pressure was 2.4 Kg/cm ² at the front and 3.25 Kg/cm ² at the rear, and an actual vehicle feeling test (stability, maneuverability) was conducted with three test drivers. The results were compiled using a three-point evaluation method. (2) Wear resistance In a practical test, the remaining longitudinal grooves in the crown were measured and evaluated after running for 30,000 km. (3) Noise test Tire size: 7.00-15.8PR. Internal pressure: 2.40/ ^cm2 , load 530Kg/tire, sound collecting microphone placed directly beside the tire and 100cm from the center of the tire width.
Measured while driving the tire by rotating a drum in an anechoic chamber, installed at a height of 25 cm from the ground surface (compliant with tire noise test method stipulated by SASO C606). Example 2 As shown in Table 2, the dispersion state of peak levels due to harmonic components of pattern constituent units of the same composition and of different types was calculated using computer simulation, and the results were as follows:
It is shown in FIGS. 14 to 17. It is recognized that the Example products B, D, F, and H of the present invention all have better dispersion states than the Comparative Example products A, C, E, and G. [Effects of the Invention] As described above, the low noise tire of the present invention has one vertical groove.
It is composed of repeating zigzag pattern constituent units p in which 1 to 4 main elements M and 1 to 4 subordinate elements S are connected, and the pitch length ratio rP and the pitch height ratio rH are within a predetermined range. At the same time, the two types of vertical grooves are created by making the pitch length of the main element and the number of subordinate elements S different from each other, and by making the pitch length ratio rM of the main element larger than 1.10 and smaller than 2.60. Therefore, for each tire,
The peak level distribution state due to harmonic components is improved, and noise can be effectively dispersed, making it possible to reduce noise and improve driving comfort compared to conventional pitch variation tires.

【table】

【table】

【table】 [Brief explanation of drawings]

Fig. 1 is a partial plan view of the tread surface of an embodiment of the low-noise tire of the present invention, Fig. 2 is a plan view showing longitudinal grooves in detail, and Fig. 3 is the result of computer simulation of the noise. FIG. 4 is a plan view showing other vertical grooves in detail; FIG. 5 is a diagram showing the results of computer simulation of the noise;
FIG. 6 is a plan view showing another vertical groove in detail, FIG. 7 is a line diagram showing the result of computer simulation of noise, and FIG. 8 is a plan view showing another embodiment of the low-noise tire of the present invention. Partial view, Figure 9 is a partial plan view showing a comparative example product, Figure 10 is a graph showing the relationship between noise level and running speed, Figures 11, 12, and 13.
The figure is a graph showing the relationship between noise level and frequency, Figures 14 to 17 are graphs showing the relationship between peak level and harmonic components, and Figures 18 and 19 are diagrams showing other embodiments of the present invention. be. G1, G2, G3...Vertical groove, M, M1, M2, M
3...Main element, S, S1, S2, S3...Slave element, Rm, Rm1, Rm2, Rm3,
Rmi, Rmj...Pitch length of main element, Rs,
Rs1, Rs2, Rs3...Pitch length of subordinate element, L...Total pitch length of pattern constituent unit, p, p
1, p2, p3...Pattern constituent unit, rP...Ratio of pitch lengths, rH...Ratio of pitch heights, rM...Ratio of pitch lengths of main elements.

Claims (1)

[Scope of Claims] 1. A tire having a rib-type pattern having at least two zigzag longitudinal grooves extending in the circumferential direction on the tire tread surface, each of the longitudinal grooves having one main element M consisting of one chevron-shaped groove. , a zigzag structure in which one to four subordinate elements S each consisting of one chevron-shaped groove portion having a pitch length Rs in the circumferential direction smaller than a pitch length Rm which is the length in the circumferential direction of the main element M are connected. Consisting of repeating pattern constituent units p, the ratio of the pitch length Rm of the main element M of each pattern constituent unit p to the pitch length Rs of each subordinate element S included in the pattern constituent unit p (Rs/Rm =rP)
is greater than 0.200 and less than 0.225, greater than 0.275 and less than 0.308, greater than 0.358 and less than 0.475, greater than 0.525 and less than 0.642, greater than 0.692 and less than 0.700 The vertical groove has a pitch length Rm of the main element M.
and two types of longitudinal grooves using pattern constituent units in which the numbers of subordinate elements S are different from each other, and the pitch length Rmi of the main element M in the pattern constituent unit p of one type of longitudinal groove and the pitch length Rmi of the other type of vertical groove. The main element M in the vertical groove pattern constituent unit p of the type
Ratio of pitch length Rmj (Rmi/Rmj=rM (however,
A low-noise tire characterized by having Rmi>Rmj)) greater than 1.10 and less than 2.60.