JPH09109621A - Radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease load noise by providing an annular projecting part formed of rubber having the same materials as side rubber on the front surface of the side rubber in the radial direction outward from the position of the maximum carcass sectional width. SOLUTION: When a point on the front surface of a tire side part in relation to a point at which a straight line passing a point P and is parallel to a tire rotary shaft traverses a buttress part 9 and the maximum width point of a carcass 4 is taken as S, the total gauge of the region of about 40% from the point F to the point S of a line segment FS is set to the height of 10mm of the maximum height H by providing an annular projecting part 6. Thereby, the mass distribution in the part is changed in comparison with the conventional one. An annular recessed part 7 is provided inward in the radial direction, and a cange is applied to the mass distribution. To decrease load noise, one nylon-made reinforcing layer 8 having the width of 25mm to 35mm and the cord angle of 45 deg. is embedded in the buttress part 9. Therefore, load nose in the frequency band in the range of 250 to 400Hz can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire with reduced road noise, particularly 250 to
The present invention relates to a radial tire that reduces road noise in a high frequency region of 400 Hz.

[0002]

2. Description of the Related Art Due to the high quality and quietness of automobiles these days,
The road noise reduction rate is increasing as one of the required tire performances. Road noise is generated when tires vibrate due to forced input from road surface irregularities and are transmitted to the passenger compartment. Therefore, it is necessary to improve the tire vibration characteristics, but the tire vibration characteristics for vibration up to 250 Hz can be improved relatively easily by increasing the weight of the tread portion and decreasing the spring constant. But,
At present, there is no effective means for improving the vibration characteristics of tires in the high frequency range of 250 to 400 Hz.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to improve the tire side shape in a radial tire by 2
It is to provide a radial tire that achieves road noise reduction in the frequency range of 50 to 400 Hz.

[0004]

In order to achieve the above object, a radial tire according to the present invention comprises a bead core provided on a pair of left and right bead portions, and a bead core extending from one bead portion to the other bead portion. A carcass ply consisting of a radial cord layer wound around the bead portion and wound, and a belt consisting of one or more cord layers arranged radially outside the crown portion of the carcass ply,
In a pneumatic tire comprising a tread arranged radially outside the belt and a side rubber arranged outside the tire shaft of the carcass ply, on the side rubber surface,
An annular convex portion made of rubber of the same quality as the side rubber is provided radially outward of the position of the maximum cross-sectional width. Further, if an annular concave portion is provided on the side rubber surface on the inner side in the radial direction from the position of the annular convex portion, 250 to 400H.
This is preferable because the road noise of z can be further reduced. Further, it is preferable to embed the cord reinforcing layer in the buttress portion between the tire maximum carcass cross sectional width position and the tire width direction end portion, because road noise can be further reduced.

When the tire travels on an uneven road surface, the tire is vibrated in accordance with the uneven condition, and each part vibrates and is transmitted to the axle. 250-400 to pay attention to here
It is known that tire vibration in the frequency band of Hz is similar to vibration of a string fixed at both ends and that a standing wave is created between both bead parts as fixed ends to form a vibration mode in the radial direction. There is. However, the current situation is that the relationship between the tire transfer characteristic and the tire vibration mode is not clear.

In the present invention, it was found based on the following knowledge that the above-mentioned means can reduce the road noise of 250 to 400 Hz. That is, (1) In the vibration mode in the band of 250 to 400 Hz, the belt end portion, the maximum width portion of the tire and the bead fixing portion become nodes,
It has been empirically found that the buttress portion and the bead portion have a belly in the radially outer portion. (2) In the band of 250 to 400 Hz, it was confirmed that the vibration transmission characteristic of the tire can be reduced by suppressing or adjusting the amplitude of the vibration mode of the buttress portion. In general, when the structure exhibits a certain vibration mode form, when the rigidity / mass of another point is changed in order to suppress the mode amplitude of any point, it is necessary to increase or decrease it. Is known to depend on.

From the above, the inventors have made various attempts to change the mass distribution from the buttress of the tire to the side wall, and as a result, the present invention has been achieved.
In the present invention, when a point where a straight line passing through the main belt end P and parallel to the tire rotation axis crosses the tire buttress surface is F and a point of the tire side wall portion corresponding to the tire carcass maximum width portion is S, the line segment FS 40 from F to S
An annular convex portion having a height H that is 2 to 5 times the typical total gauge h of the carcass maximum width portion is provided in the 60% region. Further, a concave portion is provided inside the annular convex portion in the radial direction while securing a gauge for the tire maximum width portion, thereby changing the mass distribution from the buttress to the side wall.

In this way, the reason why the road noise in the 250 to 400 Hz band can be reduced is that the vibration mode itself is changed as described above. It can be explained that by increasing the mass of the possessed part, the amplitude was reduced, and further, by reducing the natural frequency, the overall energy level could be lowered. (The energy level is proportional to the product of the square of the mass and the frequency and the square of the displacement.) Here, 40 to 60 of the line segment FS from F to S
The reason why the annular convex portion is provided in the area of% is that the mass distribution cannot be changed sufficiently at 40% or less, and the tire weight increases too much at 60% or more. In addition, unless the annular convex portion is arranged so as not to extend to the outside in the tire width direction from the point S, the maximum width of the tire may exceed the standard.

Further, at a buttress portion between the tire maximum carcass sectional width position corresponding to the annular convex portion and the tire width direction end portion of the belt, 30 to 50 ° with respect to the tire circumferential direction.
By embedding the reinforcing layer made of the organic fiber cord, the above-mentioned effect is further exerted, so that the road noise can be reduced. The angle of the reinforcing cord layer with respect to the circumferential direction is optimally around 45 °. As the cord type, nylon, polyester, aromatic polyamide or the like can be used.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to
A radial tire of / 65R14 will be described as an example with reference to the drawings. As shown in FIG. 1, in this embodiment, if a straight line passing through the point P and parallel to the tire rotation axis crosses the buttress portion F and a point S on the surface of the tire side portion corresponding to the carcass maximum width point, a line segment is obtained. About 4 from F to S of FS
The total gauge in the 0% area is set to a maximum H height of 10 mm by providing the annular convex portion 6, and is about three times as large as the typical total gauge h of the carcass maximum width portion of 3 mm. The mass distribution of this part is changed from that of the conventional tire. An annular recess is provided on the inner side in the radial direction to further change the mass distribution. Although there is a restriction that the gauge around this concave portion cannot be freely changed, this concave portion is an important portion in the sense that the mass distribution can be largely changed from that of the conventional tire.

In the present embodiment, the buttress portion has a width of 25 mm and 35 mm to further reduce road noise.
One nylon reinforcing layer with a cord angle of 45 ° is embedded. In this case, embedding a plurality of layers is effective against road noise, but it is not preferable because the riding comfort when overcoming the protrusion is deteriorated.

In order to confirm the effect of the present invention, a radial tire for passenger cars having a tire size of 195 / 65R14 having the structure shown in FIG. 1 was prototyped under the specifications shown in Table 1. For comparison, a tire having an ordinary side shape was prepared. Note that these tires have the same structure except for the side shape and the presence or absence of the reinforcing layer. The gauge ratio in the table means the value of H / h in FIG.

These tires were mounted on a 6JJ rim with an internal pressure of 2.
The test was conducted using a domestic 2000cc passenger car assembled at 0kg / cm ² . Road noise is 50 km / h
The vehicle interior noise was measured at h, and the result is shown in Table 1 as a comparative example 100. The larger the index, the better.

[0014]

[Table 1]

[0015]

As is apparent from the above description, according to the present invention, road noise in the frequency band of 250 to 400 Hz can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view in a tire width direction showing an embodiment of the present invention.

[Explanation of symbols]

1 tire 2 bead portion 3 bead core 4 carcass 5 belt 6 annular convex portion 7 annular concave portion 8 reinforcing layer 9 buttress portion P main belt end F point where a straight line passing through the point P and parallel to the tire rotation axis crosses the buttress portion S carcass A point on the surface of the tire side that corresponds to the maximum width point H Total gauge of annular protrusion h Typical representative gauge of carcass maximum width

Claims (3)

[Claims] 1. A bead core provided on a pair of left and right bead portions, and extending from one bead portion to the other bead portion,
A carcass ply consisting of a radial cord layer wound around the bead core and anchored to the bead portion, and a carcass ply having a crown portion radially outwardly disposed in the crown portion
In a pneumatic tire comprising a belt composed of at least two cord layers, a tread arranged radially outside the belt, and a side rubber arranged outside the tire shaft of the carcass ply, the side rubber surface has a maximum A radial tire, characterized in that an annular convex portion made of rubber of the same quality as the side rubber is provided on the outer side in the radial direction from the position of the carcass cross-sectional width. 2. The radial tire according to claim 1, wherein an annular concave portion is provided on the surface of the side rubber inward of the annular convex portion in the radial direction. 3. The radial tire according to claim 1, wherein a cord reinforcing layer is embedded in a buttress portion between the tire maximum carcass cross sectional width position and the tire width direction end portion.