JPH03253406A - Radial tire - Google Patents

Abstract

PURPOSE:To reduce a road noise by arranging reinforcing members covering a carcass on a part which is between a maximum width part and both ends of the grounding part in the width direction and moves in a cross section direction inner side due to excitation to a grounding part to become a protruded end in a radial tire for an automobile. CONSTITUTION:Reinforcing members 6 covering a carcass 2 are arranged between the maximum width part, Wmax part, and both ends of a grounding part T in the width direction in a tire. The reinforcing members 6 are composed of a nylon cord ply which is a nylon cord rubber-coated. Two layers of the nylon cord ply are buried in a tire tread rubber 1 to be arranged on one side and another side in the width direction. The diameter outer end of each nylon cord ply is extended to the width direction end part of a steel belt 3, and the diameter inner end is prolonged to a carcass folded end. This constitution can cope with the high performance and high grade of a tire and reduce a road noise.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a radial tire, and is intended to reduce road noise of an automobile equipped with a radial tire.

(Prior Art) In recent years, as automobiles become more sophisticated and sophisticated, it is desired to reduce the noise generated inside the automobile. One example of such noise is road noise, which is caused by the vibration of tires being transmitted and vibrating the air inside the vehicle.

The magnitude of this road noise varies depending on the frequency, and depending on the natural frequency of the tire, the acoustic characteristics of the interior of the vehicle, etc., noise in a specific frequency range has a peak value, is emphasized, and is perceived as noise.

Conventionally, the natural frequency of the tire was lowered by increasing the rubber weight of the tread or reducing the spring constant, and the relationship between this natural frequency and the acoustic characteristics of the vehicle interior was made different. , a relatively low frequency (approximately 100 to 2
00H2) was aimed at reducing road noise.

Additionally, since radial tires generally produce less road noise than bias tires, radial tires are installed to reduce road noise.

(Problem to be solved by the invention) Conventionally, road noise reduction by lowering the natural frequency by increasing the weight of the tire or reducing the spring constant has a peak at a relatively low frequency. However, it was not effective in reducing road noise that is emphasized by having a peak at a relatively high frequency (approximately 2508Z or higher).

Therefore, in the case of automobiles where high-frequency road noise is particularly emphasized, there has been no countermeasure in the past.

Therefore, an object of the present invention is to provide a radial tire that can effectively reduce relatively high-frequency road noise.

(Means for Solving the Problems) The radial tire according to the present invention is characterized in that the radial tire is located between the maximum width part of the tire and both ends of the ground contact area in the width direction, and when the ground contact area is excited, the radial tire vibrates inward in the cross-sectional direction. The point is that a reinforcing member that covers the carcass is arranged at the part that swings and becomes the protruding end.

(Function) The reason why road noise is reduced by the radial tire having the configuration of the present invention is based on the following findings by the inventor of the present invention.

When analyzing the response characteristics when vibration is input to the tread portion of a radial tire, the vibration modes can be classified into a relatively low frequency range of about 2008Z or less and a relatively high frequency range of about 250412 or more.

Corresponding to the vibration characteristics of radial tires, the peak value of road noise for cars equipped with radial tires is approximately 1
A relatively low frequency range of about 00 to 200 Hz and about 250 Hz
It exists in a high frequency range of H2 or higher.

And, when the tread part of a radial tire is vibrated, the way of vibration in the cross-sectional direction of the tire in the low frequency range and high frequency range (vibration mode) is explained in the 61st! I and FIG.

61st! l indicates the vibration mode in the high frequency range when the tread is vibrated, and the 71st! l indicates a vibration mode in a low frequency range when the tread is vibrated.

In each figure, dashed lines and solid lines indicate modes of vibration.

In the low frequency range, the entire periphery vibrates in a mode, and when viewed in the cross-sectional mode, the entire tread and the entire side vibrate in different phases (from this, the rubber weight of the tread It can be seen that by increasing the spring constant or decreasing the spring constant of the side part, the natural frequency will be lowered, and as explained in the conventional example, the road noise in the low frequency range will be reduced.)

On the other hand, in the vibration mode in the high frequency range, a locally vibrating part occurs in the upper part of the side, and the maximum width part of the tire (
WmAx) It is recognized that there is a portion (^) that swings inward and becomes a protruding end between the iB portion and both ends of the grounding portion (T) in the radial direction.

This is because while conventional radial tires use belts and nylon cap braces in the tread area and bead fillers and folded carcass in the lower side areas to improve rigidity, the maximum width area This is because only a carcass exists between the widthwise ends of the ground contacting part and the rigidity is low.

Therefore, if a reinforcing member is placed to cover the carcass at the part (A) that vibrates inward when the tread is vibrated and becomes a protruding end, the rigidity of that part increases and vibrations in the high frequency range are suppressed. The road noise can be reduced by shifting the frequency to a higher one, and the relationship with the acoustic characteristics of the vehicle interior in the high frequency range becomes different.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing the schematic structure of a radial tire according to a first embodiment of the present invention, in which 1 is tire tread rubber, 2 is a carcass, 3 is a two-layer steel belt, 4 is a radial tire according to a first embodiment of the present invention.
5 indicates a bead wire, and 5 indicates a bead filler.

Then, the maximum width part (LAx) of the tire and the ground contact part (
A reinforcing member 6 that covers the carcass 2 is arranged between both ends of the carcass T) in the width direction.

The reinforcing member 6 of this first embodiment is a nylon cord ply in which nylon cord is coated with rubber, and two layers of each nylon cord ply are embedded in the tire tread rubber 1 on the front side and the other side in the width direction. It is something. Further, the radially outer end of each nylon cord ply reaches the widthwise end of the steel belt 3, and the radially inner end thereof reaches the folded end of the carcass 2.

FIG. 2 shows a schematic structure of a radial tire according to a second embodiment of the present invention. The difference from the first embodiment is that in the first embodiment, the reinforcing members 6 are arranged on one side and the other side in the width direction, whereas in the second embodiment, the vibration damping is on one side and the other side in the radial direction. The member 6 is integrated with a reinforcing member 7 that covers the outer diameter of the steel belt 3 and reinforces the tread portion. Note that the reinforcing member 7 is made of two layers of nylon cord ply, similar to the reinforcing member 6. The rest is the same as in the first embodiment and is indicated by the same reference numerals.

FIG. 8 shows a schematic structure of a radial tire according to a conventional example, in which the reinforcing member 6 as in the above embodiment is not arranged, and it is made of two layers of nylon cord ply covering the radially outer side of the steel belt 3. Only the reinforcing member 7 is arranged. The rest is the same as in the above embodiment and is indicated by the same reference numerals.

Next, the radial tires of the above-mentioned first and second embodiments and the conventional example were mounted on a car, and the results of measuring the road noise were measured in the first test.
It is shown in the table, FIGS. 3 and 4.

The measurement conditions are as follows.

・Tire size: 185 /65 R14-85H
・Tire internal pressure: 2. OKgf/cm” Steel belt width Inner diameter force: 145mm Outer diameter: 135m
m・Radius of each reinforcing member 6 in the first embodiment: 100m+r+・
Total width of each reinforcing member 6.7 in the second embodiment: 300 mm.
Width of reinforcing member 7 in conventional example: 150mm Rim size: 13X 5'/2-J Traveling speed: 60Xm/h Vehicle type: Sedan type with a displacement of 1800cc
Tire load: Car, 2 passengers and measuring equipment Weight Test course: Road noise evaluation road And sound collection microphones were installed on the left and right sides of the driver's seat backrest, and each sound collection microphone was positioned on either side of the driver's ears. FIG. 3 shows the measurement results with a sound-collecting microphone located on the window side of the car, and FIG. 4 shows the measurement results with a sound-collecting microphone located on the center side of the car.

In Table 1, Figures 3 and 4, the horizontal axis shows the frequency of road noise, the vertical axis shows the sound pressure of road noise, the dashed line is the conventional example, the one-dot chain line is the first example, and the two-dot chain line is the The results of each measurement in Example 2 are shown.

From the above measurement results, it can be confirmed that in the high frequency range of about 250H2, the peak value of the sound pressure of the road noise is lower in the example than in the conventional example. Also,
The total sound pressure is also reduced.

FIG. 5 shows a third embodiment, which differs from the above embodiment in that instead of using a vibration damping member made of nylon cord, the width of the radially inner steel belt 3 is extended, and the extended portion is used as a reinforcing member 6. That's the point. The rest is the same as in the above embodiment and is indicated by the same reference numerals.

Note that the reinforcing member is not limited to nylon cord plies or steel belts, and may be any material that can improve rigidity.

Further, in each of the above embodiments, the reinforcing member 6 has the maximum width portion (1
1i, 1AX) and both ends in the width direction of the grounding part (T), but due to vibration to the grounding part (T), it swings inward in the cross-sectional direction and the protruding end (A) Any position that covers the carcass 2 is sufficient.

(Effects of the Invention) According to the radial tire according to the present invention, road noise in a relatively high frequency range can be reduced by arranging reinforcing members at predetermined positions, and it can correspond to high performance and high-class automobiles, and is easy to use. Since it can be implemented with a simple structure, it can be put into practical use at low cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a radial tire according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a radial tire according to a second embodiment of the present invention, and FIGS. A diagram showing the relationship between frequency and sound pressure, FIG. 5 is a cross-sectional view of a radial tire according to a third embodiment of the present invention, FIGS. 6 and 7 are diagrams each showing the vibration mode of the tire, and FIG. 8 1 is a sectional view of a radial tire according to a conventional example. 2... Carcass, 6... Reinforcing member, A... Portion that swings inward in the cross-sectional direction due to vibration to the ground contact portion and becomes a protruding end.

Claims (1)

[Claims] (1) A reinforcing member covering the carcass is placed between the maximum width part of the tire and both widthwise ends of the ground-contacting part, at a part that swings inward in the cross-sectional direction due to vibration to the ground-contacting part and becomes a protruding end. A radial tire characterized by: