JPS60116510A - Low noise, pneumatic tire - Google Patents

Abstract

PURPOSE:To ensure low noise and stable travel of a car on a wet road and prevent a crack at a boundary area between weir plates and the groove bottom from occurring in a low noise tire, whose rag grooves are provided with weir plates, by properly specifying the arrangement and profile of the paired weir plates. CONSTITUTION:At least one pair of weir plates 4 are formed at a place whose distance l from an open end 2 of a rag groove 3 is less than 25mm.. The weir plate 4 consists of an upper domain 4a and a lower domain 4b. The projected length b of the upper domain 4a into the groove 3 is set to 20-48% of the groove width B at the same place, while the height d of the upper domain 4a is set to 30-80% of the groove depth D. The mean thickness t of the weir plate 4 is set to 10-80% of the projected length of the weir plate 4 at the tire surface. In addition, the projected length of the lower domain 4b into the groove is made smaller than that B of the upper domain 4a, and the lower domain is formed into a recessed shape against the groove walls. With this constitution, low-noise and stable travel on a wet road can be ensured, and occurrence of a crack at a boundary area between the weir plate and the groove bottom can be prevented.

Description

[Detailed description of the invention] The present invention relates to a low noise pneumatic tire.

In a pneumatic tire that has a large number of grooves, or lug grooves, on both sides of the tire's equator, one end of which opens to the side of the tire shoulder, the above-mentioned lug grooves are installed in order to reduce the pattern noise that occurs when the tire is running. By providing a weir plate protruding toward the center of the groove on both groove walls, the speed of the airflow due to the pumping effect at the time of the ground is reduced, while the frequency of the air columnar resonance sound formed by the lug grooves is dispersed. A device is known in which the audibility level is lowered (see Japanese Utility Model Publication No. 58-22301).

However, in the above-mentioned known low-noise pneumatic tires, the protruding length of the weir plate is large, the tip of the sheath plate exceeds the center line of the lug groove, and the same is formed in the part that contacts the groove bottom, so When driving on the ground, drainage performance of the lug groove is hindered and running stability is reduced, and when the ground is touched, large stress is applied to the connection between the weir plate and the groove bottom, causing cracks in the connection. This occurs and grows, reducing the life of the tire.
It has the disadvantage of making it more difficult to use.

This invention is based on the above-mentioned lag i7. ! In a low-noise pneumatic tire equipped with a weir plate, the so-called pattern noise is the same as the above-mentioned known low-noise pneumatic tire IIi+.

11. It is possible to suppress the occurrence of cracks due to stress concentration at the boundary between the weir plate and the groove bottom, while ensuring running stability on wet roads. It was designed so that

However, the present invention has a plurality of lug grooves on both sides of the equator of the tire, one end of which opens to the side of the tire shoulder, and both of these lug grooves have j7. In a low-noise pneumatic tire with a shear plate protruding from the i' wall toward the center of 11'1\, the above-mentioned shear plate is on both f! ':' An upper region in which the walls are protruded in rows from substantially opposite positions, and the weir plates are close to the groove III, and! (The upper area excluding the upper area is IE, i' in the icy depth direction,
- in the meaning place "9" - 1 - part 141? The protrusion length is set to 20 to 48% of the groove width at any position above, and the protrusion length is set such that the tip of the second part lower region is recessed from the tip of the eleventh part region toward the groove wall side and touches the groove bottom. is set smaller than the part of the tire area, and the uniform thickness of the slat is 10 to 80% of the protruding length of the slat from the tire surface. Nibu Segi (1 ton of rug)
This low-noise public tire is characterized in that at least one pair of tires protruding from one side of the tire shoulder of Φ is provided at a distance of 15 discs or less in the tire meridian direction.

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

In FIG. 1, ■ is the tread of the lug tire, 2 is the tire shoulder, and 3 is the lug 'Ii1. P is the equator, and a pair of first weir plates 4.4 are provided protruding from opposing positions of both groove walls 3a, 3a of this lug groove 3. As shown in FIG. 2, this weir plate 4 includes an upper region 4a whose tip is formed into a straight line;
It consists of a lower region 4b whose tip is formed in a curved shape, and the tip of the lower region 4b extends from the tip of the "-" section region 4a to the groove wall 3.
It is recessed toward the a side and inscribed in the groove bottom.

Generally, when a tire rotates under load, each part of the tread 1 repeatedly contacts the ground every rotation, and a large shear strain occurs in the groove bottom of the lug groove 3 each time it makes contact with the ground. A large tensile strain occurs when the part is exposed, so if there is a protrusion like a conventional weir in this part, the stress at the base of the protrusion is (1, (
However, since the weir plate 4 of the two-part embodiment is provided with a lower region 4b having a smaller protrusion length than the two-part region J or 4a, the above-mentioned stress can be easily generated. The inside of the tire is reduced, no cracks occur, and the life of the tire is extended.

Since the lower region 4b of the second part exists, the grooves 1 to 1 contact the ground, and the groove width of the lug groove 3 is reduced, and the weir plate 4.4
Even when the two-part regions 4HI and 4a are overlapped and closed, a hole is formed between the tips of the lower regions 4b and 4b, which facilitates drainage when driving on a wet road and ensures running fj stability. Ru.

” ; The protruding length of one part area 4a of the marking plate 4 is the lag)
114 of t43! The width is set to 20 to 48'X.

That is, the protrusion length b of the second part region Jul 4 d at any position in the groove depth direction is set to 20 to 48% of the groove width B at any position of the second part. If the length of the protrusion L is less than 20% of the groove width B, it is too small and it is difficult to generate vibration wave nodes for air column vibration, and therefore the air column vibration frequency does not change, resulting in a low ear t- If the effect of changing exceeds t; on the other hand, 48ヾ), then 1-Lets 1
Weir plate 4 due to the reduction of jM1 width Y3 at the time of <1 grounding.
The overlapping length of the weir plate 4 is excessively large, increasing drainage resistance when driving on wet roads, and reducing running stability.
The height d (length in the depth direction of ff+f') of the two-part region 4a is preferably 30 to 80%, particularly 40 to 70%, of the groove depth D. The height d of the two-part region 4a of the weir plate 4 is 3 of the groove depth D.
If it is less than 0%, the effect of providing the weir plate 4 will be lost and the purpose of noise reduction will not be achieved;
If it exceeds this, drainage performance during running on a wet road will be reduced and cracks will likely occur at the connection with the illumination bottom.

The cross-sectional shape of the weir plate 4 can be any shape, such as a rectangular shape with a constant J value as shown in FIG. 3, or a trapezoidal shape with an uneven thickness as shown in FIG. The average thickness t is the protruding length b of the weir plate 4 on the surface of the tread 1
o (see FIG. 2) is set to 10 to 80%. -1-
The article uniform thickness t is 10% of the protruding length bo of the marking plate 4.
If the rigidity of the weir plate 4 is less than
There is insufficient resistance to the pressure of the airflow generated within 1 yen, making it difficult to generate nodes of vibration waves that align with the air column vibration, resulting in
If it exceeds 80%, the rigidity is too high, and the drainage resistance when running on a wet road becomes excessive, reducing running stability, and stress concentration tends to occur at the connection with the groove wall 3a. Cracks are likely to occur in this area. Additionally, if the rigidity of the weir plate 4 becomes excessive, the resistance to the airflow will also increase, and when the groove volume P is reduced by grounding, the pressure inside the groove will increase, and some air will be forcibly discharged to the outside. It expands rapidly and generates eddy currents, which vibrate the surrounding air and increase the high frequency components of pattern noise.
You will not be able to achieve your first goal. In addition, j, Ii of 1" plate 4
It goes without saying that it gives roundness to the body.

”-The example is 1711! This is an example in which two weir plates 4.4 are protruded from a straight line perpendicular to the center line C (see No. 1 and 1), and as shown in FIG. 4. The position of 4 can be slightly shifted parallel to the groove center line C. The deviation in this case, that is, the intersection of the extension line of the weir plate 4.4 and the ill, ly center line C, is Q,
It is desirable that the distance ti+ltS between the intersection points Q and Q, where Q is defined, be set as small as the groove width 13 or less at the position where the weir plate 4 is provided. When the deviation S shown in above exceeds Hf, Y width ■3, the effect of using the two weir plates 4.4 as a pair is lost, and only one sheath plate 4 is used to suppress the vibration of the air column pipe. In this case, the protruding length of the weir plate 4 must be set to 50% or more of the groove width, resulting in the above-mentioned inconvenience.

By providing the weir plate 4, the frequency of the resonance sound of the air column composed of the lug groove 3 and the road surface is reduced to a range of 6 to 8 Kllz or higher, which is low sensitivity for the human ear. It is intended to be transferred. As is well known, the human ear is highly sensitive to the sound range of 1 to 5 KIIz, and has low sensitivity in any of the above ranges. On the other hand, the frequency f of the air column resonance sound is determined by the sound speed being V and the tube length being j.
When it starts, in a pipe with one end closed and one end open, f
= V//Ij in a tube closed at both ends, f
=v/2j. Therefore, in the first N, in order to make the resonance sound generated by the air column formed on the shoulder side of the weir plate 4 with one end closed and one end open to the human body, it is necessary to increase the length of the air column. 17 to 15+nm or less, especially 1
It is preferable to set it to 0 mn or less, and as shown in FIG. 6, one rough 1713! 3, two or more pairs of weirs 4.4 are provided, and these form an air column tube with both ends closed, in order to make humans feel the resonance sound generated by this air column tube. In this case, it is preferable to set the interval <la between the weir plates 4.11 to 30+ nm or less, particularly 20 mm or less.

Next, further explanation will be given using an experimental example.

Experimental Example 1 Size 7.50- with lug grooves shown in Figures 1 and 2
16 For a 1.4 yen automobile pneumatic lug tire, the protruding length of the weir plate 4 in the lug groove 3 was varied and J
Installed on iS standard rim; r1, under the maximum air pressure, 1 [
Loading the S maximum load and carrying out two trials at a speed of 20 to 100 Km/l+ based on JASO-CLOG, measuring the average noise level and making the graph in Figure 7. It was 1t. This graph shows the ratio W (%) of the above protruding length) to the width ■3
is plotted on the horizontal axis, and the index of the noise level (b/n=2
The noise level at 0% is set to 100. ) is taken on the vertical axis. As is clear from a glance at FIG. 7, the noise level is lowest when the protruding length b of the weir plate 4 is 25 to 30% of the groove width 13, and the protruding length b is smaller than 20%. In this case, the effect of Sekikari 4 is lost and the noise level rises rapidly.

However, when the above-mentioned protruding length becomes larger than 30%, the noise level gradually increases, but this is due to the fact that the weir plate 4. A closed tube with both ends closed is formed in the lug groove on the equator side of
This is presumed to be due to the addition of high frequency components due to rapid expansion. That is, if the protruding length of the weir plate 4 is too large, the noise will increase, which will be disadvantageous not only in terms of tire durability but also in terms of noise (C).

Experimental Example 2 A lug tire of the same size as the lug tire used in Experimental Example 1 was used, and a 3W (ij type evening, ear (f ,!°薯表cf.1iζ
0 and set the speed to b ('l K11l/h L:
, 'e + s' was set, and the bench test of real shell example 1 and the same Ki 13 was fj. 1p4 a) Q ) l 3m
n, the length of 1 inch on the tire surface is 4 inches (the protrusion length of l is 1
), were set to 6+11111 (b/r3=38"y,> respectively.

2 (13A written by i-fuken on the 11th table of notes: Onto Sunokuri 1-le analysis, 1-knock-down No. 81, piece 3 not shown, this 58
14).

j5V (+l+III) is 1 (L') by the test, and the number of skins is 511?
l). As is clear from this ;: HB and 1 J:, 0-ki board 1) 7.7. Comparative Example 1 where - is small is +1.6Kl17. The sound pressure level near 1 (1) is 1 (5 <) compared to the other samples, and in Comparative Example 2, where the thickness is biased toward the larger side, the lag The sound pressure level becomes high in the region 3KII7 and above due to the influence of high frequency components accompanying the ejection of air in the groove, and Example 1 in which the above thickness is appropriate is described in 2.1-], 6
There is no peak near K117°, and there are few high frequency components as described in "1". In addition, in the sound pressure level of Example 1, 6
KII7. The mountains appearing nearby are considered to be components generated from the closed pipes formed in the inner grooves of the weir plate 4.

FIG. 9 is a graph showing the speed (Km/l+) on the horizontal axis and the noise level (dn(A)) on the vertical axis for three types of samples with different thicknesses of the girder 4. In Example 1, the sound pressure level is the lowest, and the difference from the others becomes larger especially as the speed increases. This is because the higher the speed, the greater the contribution rate of the air column resonance sound as seen in Comparative Example 1, and the greater the contribution rate of the air column resonance sound as seen in Comparative Example 2.
+! It is thought that this is because the high frequency components become large as a result of the rapid volumetric contraction within.

Experimental Example 3 Four types of tires were prepared as shown in Table 2 by changing the logarithmic angle and position of the weir plate 4 using the lug tires of Example 1 used in Experimental Example 2. 1 = 1 = Thickness of the weir plate 4 [, and protrusion length b01J:, two missing itari 1 and 1
iTI-1.

Table 2 shows the four types of tires. Parsimony 2 and ln
Tests were conducted on the l tlO stand, and the obtained noise spectrum analysis results are shown in Figure 10.
6 Comparative Example 3 1.1 shown in Figure 1 respectively, the FC (Q) of the heating plate 4 was excessive, and the 10th
1"j. As shown here, the shift of the air column 1 sound frequency to the high frequency side is sufficient for J time car 1, and 4 old + 7. (
, the noise level is high near l. Also, Hiton example 4
is an example in which the weir plate 4 is not used at all, and the air column resonance frequency is the lowest among the four types of tires, 1.61 (l (exists in z). For this example, in Example 1, The resonance frequency of the air column has moved close to 6Kl17 (;l6).And in Example 2, a pair of weir plates 4, 4 are added to Example 1, and in Example 1, 61 (l() The high frequency components that existed near z are dispersed into a higher frequency range, reducing the noise level. As a result, as shown in Fig. 11.

In the noise level graph with speed as the horizontal axis, the noise level of Comparative Example 4, which does not have a weir, is the highest, followed by Comparative Example 3, which has a weir but is out of its position range, and then further. The noise level decreases in the order of Example 1, in which one pair of weir plates are provided in an appropriate range, and Example 2, in which two pairs of weir plates are provided.

As explained above, the present invention provides a pair of weir plates protruding from opposing groove walls of a lug groove, sets the protrusion length to 20 to 48% of the groove width, and sets the lower area of the weir plate to It is formed into four parts with a smaller protruding length than the upper area, and reduces noise by moving the air column resonance sound to the high frequency side that is difficult for the human ear to hear, and also reduces drainage when driving on a wet road. The tire's lifespan can be shortened by improving the tire's running stability and improving the tire's running speed by increasing the tire's running speed at 141, while also causing cracks to occur at the border between the weir plate and the groove bottom.

[Brief explanation of the drawing]

1 [■] A surface view of the tread of the embodiment of the invention, Figure 2 is a sectional view of the lug groove, Figures 3 and 4 are sectional views of the weir plate, and Figure 5 is the position of the weir plate. FIG. 6 is a surface view of another modification, FIG. 7 is a graph of the relationship between the protrusion length of the weir plate and the noise level according to Example 1, and FIG.
The figure is a graph showing the results of the noise level in Experimental Example 2, Figure 9 is a graph of the relationship between velocity and sound pressure level in the first litter Ii2, and Figure 10 is the noise level in Experimental Example I3. Graph showing the spectrum analysis results of
The figure is a graph showing the relationship between speed and sound pressure level in Experimental Example 3. 1: [-Red, 2: Tire shoulder, 3: Lug groove, 3
a:? 4 wall, /l: weir, 4a: upper area, 4
b: Lower region, P: Equator (tire circumferential center line) c: Groove center line, B: Groove width, b = protrusion length. Figure 3 Figure 41J dB(A) C) 111

Claims (1)

[Claims] (1) On both sides of the tire's equator, there are a number of lug grooves with one end opening to the side of the tire shoulder, and a weir plate extending from both groove walls of these lug grooves toward the center of 14'. Low noise with a protrusion? °1 In the pneumatic tire, the weir plates marked "-" are provided in pairs to protrude from opposite positions of both groove walls, and the weir plates marked "I" are located at the groove bottom L; in the adjacent lower area. 1 part of the area excluding the lower territory and force 11, and the protrusion length of the area is 2. 6. 20 of the groove width at the position of
~48γ, set to A, and the tip of the mark area is recessed 1° from the tip of the ten area to the side so that its protruding length is smaller than the two area. The average length of the weir slopes) is 10 to 80% of the protruding length of the weir plate on the tire surface.
The distance i' from the tire shoulder side opening end of the lug 1I111' to the tire meridian direction is 15+If11 or less.
A low-noise pneumatic retirement tire characterized by having at least one set protruding from the flt.