JPS6025807A - Low noise tire - Google Patents

Abstract

PURPOSE:To enable lowering of a noise, by a method wherein a pitch size of each element is specified by providing the surface of a tire tread with at least two longitudinal grooves and forming the longitudinal groove with a main element and 0-4 pieces subelements. CONSTITUTION:The titled tire possesses four longitudinal grooves G1, G2 in a circumferential direction and each of the longitudinal grooves G1, G2 of the tire is constituted with repetition of pattern constituent units p1, p2 made of main elements M1, M2 having pitch lengths Rm1, Rm2 and subelements S1, S2 having shorter pitch lengths Rs1, Rs2 as compared with those of the main elements M1, M2, through which a pitch size of each of the elements is specified. The pattern constituent unit p2 of the longitudinal groove G2 possesses, for example, the one main element M2 and the two and identically shaped subelements S1, S2. With this construction, tire noise can be reduced without deteriorating operation stability and resistance to wear.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a low-noise tire that reduces running noise by selecting the pitch length, etc. of each elm member 1- of pattern constituent units forming vertical grooves extending in the circumferential direction of the tire. Regarding.

In recent years, along with the need to reduce the noise of automobiles, there has also been a desire to reduce the noise caused by tires.

Generally, circumferential grooves formed on tire treads are formed by repeating pattern constituent units, which are repeating groove pattern units, in the circumferential direction. The periodic compression and release of the air contained in the generated grooves, or the pulsed vibration of each pattern constituent unit or each of its orders, generates a dense wave in the air, and pattern noise based on so-called pumping sound is generated. 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 constituent units using zigzag components with several different pitch lengths, this changes the time interval of pulse noise and vibration that occurs when tires are moved, and prevents the concentration of sound at specific frequencies. However, conventional pattern constituent units use a zigzag component, that is, a main element with an integral multiple of the length of a subordinate element, which is a zigzag component with a short pitch length. The method was determined mainly based on appearance, ease of manufacture, etc., and the method was not theoretically established and could not produce the desired effect.

On the other hand, trend design of tires has a very important influence on its properties such as braking performance, maneuverability, and wear resistance.

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 has at least two longitudinal grooves extending in the circumferential direction on the tire tread surface, and the longitudinal grooves have one main element and zero
It is composed of repeating pattern constituent units consisting of ~4 subordinate elements, and at least two vertical grooves have different pattern constituent units, while the pitch length (Rrn) and the pitch height of the main elements of each pattern constituent unit are Hm
) are larger than the pitch length Rs) of the slave element and its pinch height Hs) (Rm>Rs, Hm>
ll5), and the pitch length ratio (r P=R
s 71m) is 0.2 < r P < 0.7, and the pitch height ratio (rH=Hs/Hm) is 0.2 < rH
< 0.7, and the pitch length ratio rPl of at least one or more pattern constituent units is a low-noise tire that is not included in the region S defined below.

0.225≦N≦0.275 1/3-0.025≦N≦1/300.0250, 47
5≦N≦0.525 2/3-0.025≦N≦2/3+0.025 Furthermore, the pitch length Rrn l SRrn J of the main elements of the two vertical grooves with different pattern constituent units is set to 1. .1<r
By setting M<26, the tire is characterized by a low-noise tire with further improved low-noise efficiency.

An embodiment of the present invention will be described below with reference to the drawings.

Figure ff11 is a partial plan view of the tread surface of the low-noise tire 1 of the present invention. , the longitudinal grooves G2, G2 are arranged on both sides of the tire equator C, and the longitudinal grooves G1, Gl are arranged at approximately equal intervals along both side edges of the tire. Each of the longitudinal grooves Gl and G2 includes main elements M1 and M2 (generally referred to as main elements M) with pitch lengths Rml and Rm2, and subordinate elements 3 with shorter pitch lengths RS1sRs2, respectively.
1S2 (when collectively referred to as slave elements S), pattern constituent units p1 and p2 (when collectively referred to as pattern constituent units p
It consists of a repeating form of ). Further, the pattern constituent unit p1 of the longitudinal grooves 01 and G1 each has one main element Ml and one subordinate element S1, and the pattern constituent unit p2 of the longitudinal groove G2 has one main element Ml and one subordinate element S1, respectively.
main element (-M2) and two identical subordinate elements S2, S2, each facing vertically 1fiG1, Gl
, the longitudinal grooves G2, G2 are arranged in a symmetrical shape with the point on the tie-1 equator C as the center. In addition, in this example, each main elmmen 1-
M1, M2, secondary elm) S1 and S2 form a mountain shape inclined at approximately the same angle, so the pattern constituent unit p is formed in a zigzag shape. The pattern constituent unit p is as described below.
The main element M and the subordinate element S may be formed in a zigzag shape having a component parallel to the tire equatorial plane C.

The feature of the present invention is that each vertical groove G1, G1, G2
, G2 by adjusting the M-like configuration tiles p1 and p2 to disperse the noise. The pattern noise during tire transfer is caused by the pumping noise that occurs periodically on the contact surface for each pattern constituent unit p.
The sounds created by this pattern constituent unit p are each primary, secondary,
Sharp peaks occur in tertiary and other sounds, 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 Rm.
The pinch length ratio rp of l, Rm2 (generally referred to as pitch length Rm) and the pitch length Rsl, R52 (generally referred to as pitch length Rs) of the secondary elm + - S, that is, rP = Rs / Rm. , is set in the range of 0.2 to 0.7. Note that when the pattern constituent unit p has 2 to 4 subordinate elements S, the pitch length ratio rPl of the pitch length Rs of each subordinate element S included in the pattern constituent unit p is set to the same range.

The noise dispersion will first be explained by taking as an example the vertical groove Gl shown enlarged in FIG. 2. As mentioned above, the longitudinal groove GI is formed by one main element I-(Ml) and one subordinate element (Ml).
For such a pattern constituent unit pi, the ratio of the noise level to the pitch length (rPl) (when specifically specifying the 11 grooves, the vertical groove Gl.
By computer simulation, the relationship of the pinch length ratio rP, which is given the code 1.2- depending on the sign of - and is collectively referred to as the pinch length ratio rP, is shown in Fig. Each note changes sinusoidally with the pitch length ratio (rPi). Here, when the pinch length ratio (r P 1) is O, that is, when there is only the main element Ml, the first-order component becomes the main noise source. On the other hand, when the pitch length ratio (rPl) is 1, that is, the main element (M I
) and the pitch length of the secondary element 1-(Sl) Rml, R
When sl is the same, the secondary component becomes the main noise source. Note that, as will become clear later, the sound of the order component that is the sum of the number of main elements M and the number of subordinate elements S becomes the main noise source when the pitch length ratio rP is 1.

In the case of the tire with the pattern constituent unit p1 in Fig. 2, the sound of the secondary component is the most important, and the lowest range of the noise level of this component is the pitch length ratio (rPl) of 0.2 to 0. ．．
It becomes 7.

Furthermore, in FIG. 3, the pitch length ratio rP1 of each order component from the second to the fifth order is 1/4.1/3.1/2.2.
It is observed that the peak value is reached at the position of /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 synchronization conditions associated with computer simulation can be determined as follows.

The length dimension of the main element Ml and the subordinate element S1 in the axial direction of the tire, that is, the pinch height i (m 1, H
Replace with pulse trains U1 and U2 of the same strength as sl.

Then, this is calculated by the following formula: where Hn: n-th harmonic component CO: normalization constant Wk: pulse weighting constant L: total pitch length of pattern constituent unit k: 2nd element 1 When ik = 1, main element ) n; Number of elements in a pattern constituent unit Rrrz Pitch length of main element R5: Pitch length of subordinate element χ: Position of pulse In the above, the condition for synchronizing main element M1 and subordinate element S1 is pattern noise. is set to n=5 because the higher the order component, the lower the contribution rate to the noise.

Therefore, n=1.2.3.4.5 and j x n and J/(n
−J) If we include the pitch length ratio rP that satisfies <1, it is 1/
The four rows of 4.1/3.1/2.2/3 fit together and are the peak positions of the above-mentioned noise. Therefore, it is important to prevent the pitch length ratio rP from reaching the above value, but in addition, from this peak position, the pitch length ratio rP
It is desirable and necessary that the value of P is not included in the upper and lower ranges of 0.025, so that the pitch length ratio rP
is excluded from the next exclusion range (N).

1/4-0.025; N≦1/4+0.0251/3-
0.025≦N;i;1/3+0.0251/2-0.
025≦N≦1/2+0.0252/3-0.025≦
N≦2/3 +0.025, that is, the exclusion range N is 0.22
5 or more and 0.275 or less, 0.308 or more and 0.3
58 or less, 0.475 or more"') 0.525 or less, 0
．． 642 or more and 0.692 or less.

Next, the vertical groove G2 will be explained. As described above, the vertical groove G2 includes a pattern constituent unit p2, which is a combination of one main element M2 and two subordinate elements s2 and G2 of the same size, as shown in FIG. FIG. 5 shows the results of a computer simulation of the relationship between the pitch length ratio rP2 of the vertical grooves G2 and the noise level. Vertical groove G2 is 11
This is a combination of an FM main element M2 and two subelements S2, and the total number of both elements is 3, that is, the 3rd order has the most influence on noise. The third-order sound also has a pitch length ratio rP
It is recognized that the noise level is the lowest when 2 is in the range of 0.2 to 0.7.

Furthermore, the low-noise tire 1 of this embodiment combines the vertical grooves G1, G1 made up of the pattern constituent unit p1 shown in FIG. 2, and the vertical grooves G2, G2 of the pattern constituent unit p2 shown in FIG. #v! Ratio of pitch lengths Rml and Hm2 of main elements M1 and M2 of groove G2 and longitudinal groove G1 (r m = Rm 1 / Rm
2, however, if Rm 2 < Rm l) is 1.1~
It is set in the range of 2.6. Furthermore, even when the low-noise tire has different types of pattern constituent units p, the ratio of the pitch length Rmi of the main element M of a different length to the pinch length RmJ of the main element M of a smaller length. Define rM in the same way. Here, the pattern constituent units are different,
The pitch length of the main element M with the larger pitch length among the two vertical grooves in any combination to be compared is Rmi
, the smaller one is expressed as pitch length RmJ.

When rM is smaller than 1.1, noise dispersion is not effective and the effect of employing the composite longitudinal groove cannot be expected.

Furthermore, if rm exceeds 2.6, the difference in pitch length of the main elements M becomes too large, resulting in a large difference in pattern rigidity, resulting in adverse effects such as uneven wear.

Also, the main element M and the subordinate element S in the pattern constituent unit
In other words, as mentioned above, the pitch heights Hm and Hs of the main element M and the sub-element S in the axial direction of the tire are such that the ratio (rH=Hs/Hm) is 0.
．． It is necessary that it is in the range of 2 to 0.7. When the 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. do. By setting the pitch height ratio rH to a range approximately equal to the pitch length ratio rP, each height of the main element M and the subordinate element S is made approximately similar to its pitch length, and the vertical IGI , the inclination angles of the grooves in G2 are approximately equalized. This is to reduce changes in pattern rigidity and prevent adverse effects on uneven wear.
Furthermore, as the pitch height of the slave element increases, the inclination angle increases, and this is to prevent the noise level from increasing.

In addition, FIG. 6 shows a pattern constituent unit p3 which is a combination of one main element M3 and three subordinate elements S3, G3, and G3.
, and the ratio of the length of the bi-notch carved on it (r P 3)
Figure 7 shows the results of a computer simulation analysis of the relationship between noise level 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 a pitch ratio (rP
) is found to be the lowest in the range of 0°2 to 0.7.

In this way, the low-noise tire of the present invention has the shape of each element, pitch length, etc. of the pattern constituent units constituting each longitudinal groove adjusted, and also has two vertical grooves having different pattern constituent units.
By combining more than one type, it is possible to effectively disperse noise.

In addition, in the low-noise tire of the present invention, the vertical grooves are those consisting of pattern structural units p4 and p5 having a component parallel to the tire equator C in the main element l-M, as shown in FIG. As shown in Fig. 19, a pattern constituent unit p6 including main elements M having different rounding angles on the left and right sides of the vertical groove G, and as shown in Fig. 20, main elements M
Further, as shown in FIG. 21, the number of main elements M1 and the number of subordinate elements N are the same, and the pitch length Rm is 4.1 m5,
By changing only Rs4 and Rs5, it is possible to freely transform the pattern constituent units p8 and p9 into different pattern constituent units p8 and p9, and the total pitch length L of the pattern constituent units p can also be made different, and in one pattern constituent unit. It is also possible to mix subordinate elements S with different pitch lengths.

Example 1 An L/1'' tire with tie size 7.00-15 BP'H, and a different product l whose tread design has vertical grooves G1 and G2 of each pattern constituent unit shown in FIG. 1, A main element M2 and two subordinate elements S2 and G2 shown in FIG.
A separate product 2 according to the present invention in which vertical grooves G2, G2 and a main element M3 of a pattern constituent unit p2 consisting of 2 and vertical grooves G3, G3 of a pattern constituent unit p3 consisting of three subordinate elements S3, G3, G3 are provided. Table 1 shows a comparative tire having four longitudinal grooves G a- of the same shape of the pattern constituent unit pa that repeats the main element Ma and one secondary element Sa shown in FIG. 9. A prototype was manufactured with the specifications shown.

Then, noise tests, abrasion resistance, stability, and properties were examined in detail.

Regarding wear resistance and handling stability, Table 1 shows the noise test, and Fig. 10 shows the influence of the noise level depending on the traveling speed in each case, and Figs. 11 to 13 show the frequency dependence of the noise level. It shows gender. FIG. 11 shows a comparative product, FIG. 12 shows a practical product 1, and FIG. 13 shows a practical product 2. It is recognized that both Examples 1 and 2 are significantly improved in terms of noise level reduction and sound dispersion.

＼ ＼ ＼ ＼ The values in Table 1 are expressed as an index, 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) Steering stability Front and rear t & For tires with 7.00-158 Prl, internal pressure is 2.4 kg/cJ at the front and 3.25 kf at the rear.
/c1a', actual vehicle feeling test (stability,
Maneuverability) was conducted by three test drivers, and the results were compiled using a three-point evaluation method.

(2) Wear resistance was evaluated by measuring the amount of residue left in the longitudinal grooves of the crown after running for 30,000 km in a practical use test.

(3) Noise test Tire size + 7.00-158PR.

Internal pressure: 2.40/cJ, load 530 kg/tire,
Place the sound collecting microphone 10 minutes from the center of the tire on the side of the tire.
Measured while driving the tire by rotating the drum in an anechoic chamber with a gap of 0 cm, installed at a height of 25 CII+ from the ground plane (based on the tire noise test method stipulated by SAso c60G).

Example 2 As shown in Table 2, the dispersion state of the peak level due to the harmonic components of the pattern constituent units of the same composition and those of different types were calculated by B1 using a computer simulation. It is shown in FIGS. Products B, D, F, and H according to the present invention are comparative products A, C,
It is recognized that both the dispersion states are better than those of E and G.

\ \ Table 2

[Brief explanation of the drawing]

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 the 11 grooves, and Fig. 3 shows the results of a computer simulation of the noise. Fig. 4 is a plan view showing the results of computer simulation of the noise, Fig. 6 is a plan view showing the other longitudinal grooves,
FIG. 7 is a line diagram showing the computer simulation result of the noise, FIG. 8 is a partial plan view showing another embodiment of the low-noise tire of the present invention, FIG. 9 is a partial plan view showing a comparative product, Figure 10 is a graph showing the relationship between noise level and running speed, Figures 11, 12, and 13 are graphs showing the relationship between noise level and frequency, and Figures 14 to 17 are graphs showing the relationship between peak level and harmonic components. Graphs showing the relationship, FIGS. 18 to 21 are diagrams showing other embodiments of the present invention. G1, G2, G3--Ta groove, M, Ml, M2, M3--Earthwork/ment, S, 31
, S2, S3 - slave elements, Rm, Rml, Rm2.
1m3, Rml, RmJ - Pitch length of main element, Rs, Rsl, Rs2, R53 - Pitch length of subordinate element, L... - Total pitch length of pattern constituent unit, p
, pl, p2, p3 - pattern constituent units, rP - pitch length ratio, rH - pitch height ratio, rM - pitch length ratio of lifetime elements. Patent, Applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Naemura Masakugi 56 Figure p3 Figure 7 completed r)'J (Hs3/Rm3) ub LJ, F51.1J
Fig. 8 Fig. 9 1 or 4 # degree (Km/l-1) Fig. 14 Harmonic 7th grade Fig. 15 Bar 7 Nix Minus harmonics component Fig. 17 - 72 liss component Fig. 18 1520 Figure 19 Figure 6 Figure 21

Claims (1)

[Claims] +11 The tire tread surface has at least two longitudinal grooves extending in the circumferential direction, and the longitudinal grooves include one main element and
It is composed of repeating pattern constituent units consisting of four subordinate elements, and at least two vertical grooves have different pattern constituent units, while the pitch length (Rm) and the pitch height of the main elements of each pattern constituent unit are Hm) is larger than the pitch length Rs) of the subordinate element and its pitch height 11S) (Rm>Rs, Hm>Hs), respectively.
), and the ratio of the pitch length Rm of the main element 1 to each pattern constituent unit to the pitch length Rs of each subordinate element included in the pattern constituent unit (rP=Rs/Rm
) is Q, 2<rP<0.7, pitch height ratio (rH-Hs/Hm) is 0.2<r■1
<0°7, and furthermore, the pitch length ratio rPl of at least one pattern constituent unit is not included in the region N defined below. 0,225≦N≦0.275 1/3-0.025≦N≦1/3 + (1,02
50, 475≦N≦0.525 2/3-0.025≦N≦2/3 + 0.025
(2) The low-noise tire according to claim 1, wherein the at least two vertical grooves have different numbers of subordinate elements so that their pattern constituent units are different. (3) The low-noise tire according to claim 1, wherein the at least two vertical grooves have different pitch length ratios rPl, so that their pattern constituent units are different. (4) Ratio of pitch lengths Rmi and Rmj of the main elements of at least two vertical grooves having different pattern constituent units rM=R
tnl/RmJ <Rml>RmJ) is 1, 1 < r
A low-noise tire according to item 1, 2, or 3 of the scope of Patent 1, characterized in that M < 2.6. (5) The low-noise tire according to claim 1, wherein at least two or more pattern constituent units have mutually different total pitch lengths. (6) The low-noise tire according to claim 1, wherein the pattern constituent unit has one main element and two or more subordinate elements having different pitch lengths.