JP5061606B2 - Pneumatic radial tire - Google Patents

Description

  The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire in which road noise in a frequency range of 200 to 400 Hz is reduced without increasing the mass of the tire.

  There is a strong demand for reducing noise caused by tires as vehicles become more sophisticated and quieter. In general, the sound pressure level of road noise caused by tire vibration varies depending on the frequency as shown in FIG. 2, and the primary peak exists in the region of 100 to 200 Hz, and the secondary peak exists in the region of 200 to 400 Hz. .

  The former road noise reduction measures in the low frequency range can be achieved relatively easily by increasing the rubber in the tread portion or decreasing the longitudinal spring constant of the tire. On the other hand, in order to reduce the road noise in the latter high frequency region, it is known that the above-described method cannot be used, and it is necessary to change the vibration mode in the tire cross-sectional direction.

  That is, the vibration mode in the 200 to 400 Hz region of the tire creates a standing wave with the bead portion as a fixed end, the shoulder portion and the tire maximum position in the tire cross section become nodes, and the tread center portion, buttress portion and bead upper region are Since each has a belly mode, the road noise is reduced by suppressing the butterfly belly.

Conventionally, as part of the method described above, a proposal has been made to reduce the road noise by reducing the amplitude by placing a high specific gravity rubber on the buttress part and increasing the weight of the antinode of vibration mode. (For example, Patent Document 1). However, in this type of proposal, high-mass rubber is placed on the left and right buttresses, which increases the weight of the tire, causing other tire performance such as riding comfort and rolling resistance to deteriorate. It was.
JP 2001-191742 A

  An object of the present invention is to solve such a conventional problem, and to provide a pneumatic radial tire that reduces road noise in a frequency range of 200 to 400 Hz without increasing the mass of the tire. It is in.

In order to achieve the above object, the pneumatic radial tire of the present invention is an air in which at least one carcass layer is mounted between a pair of left and right bead portions, and a belt layer is disposed on the outer periphery of the carcass layer in the tread portion. In the entering radial tire, in the left and right regions from the both ends of the belt layer to the tire maximum width position, rubber having a mass higher than the periphery in the tire radial direction is disposed in one region, and the tire diameter is disposed in the other region. by arranging the direction of a rubber lower mass than the surrounding, Rutotomoni with different mass distribution in left and right tires, side where the mass and mass Ga in the region of the mass was disposed a high rubber side placed the lower rubber The ratio Ga / Gb to the mass Gb in the region is set to 1.2 to 2.0 .

Furthermore, in the structure mentioned above, it is preferable to comprise as described in (1)-(4) below.

(1) At least one of barium sulfate, titanium oxide, and zinc oxide is blended with the high-mass rubber, and a foaming agent is blended with the low-mass rubber.

(2) A recess is formed at the maximum tire width position on the higher mass side.

(3) An asymmetric pattern having different groove area ratios on the left and right sides of the tire equator is formed in the tread portion, rubber having a high mass is disposed on the side where the groove area ratio is large, and the groove area ratio is on the side where the groove area ratio is small. A rubber having a low mass is disposed.

(4) The side where the high-mass rubber is arranged is attached to the inside of the vehicle, and the side where the low-mass rubber is arranged is attached to the outside of the vehicle.

  According to the present invention, the mass of the rubber disposed in the left and right regions from the both ends of the belt layer to the tire maximum width position is higher than the peripheral rubber in the tire radial direction in one region, and in the tire radial direction in the other region. Since the amplitudes in the left and right regions forming the antinodes of the vibration mode are changed from each other, road noise in the frequency region of 200 to 400 Hz can be reduced.

In addition, while increasing the mass on the left and right sides of the tire, decreasing the mass on the other side offsets the increase and decrease of the rubber mass on the left and right, so there is no increase or decrease in the total tire mass. Further, deterioration of other tire performances such as riding comfort and rolling resistance can be prevented.
Moreover, since the ratio Ga / Gb between the mass Ga of the rubber on the higher mass side and the mass Gb of the rubber on the lower mass side was adjusted to 1.2 to 2.0, preferably 1.4 to 1.8, Road noise can be reduced without deteriorating riding comfort and uneven wear resistance.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing a pneumatic radial tire according to an embodiment of the present invention.

  In FIG. 1, a pneumatic radial tire 1 has at least one carcass layer 3 mounted between a pair of left and right bead portions 2 and 2, and a belt layer 5 (2 in the figure) on the outer periphery of the carcass layer 3 in the tread portion 4. Layer). In the left and right regions T and T respectively extending from the both end portions 5a and 5a of the belt layer 5 to the tire maximum width positions 6 and 6, rubber having a higher mass than the periphery in the tire radial direction is disposed in one region T, and the other region. A rubber having a lower mass than the periphery in the tire radial direction is arranged on T, and the mass distribution is made different on the left and right sides of the tire. In FIG. 1, the mass Ga of the rubber GA is higher than the mass Gb of the rubber GB (Ga> Gb).

  The method of making the masses Ga and Gb of the rubber GA and GB different in the left and right regions T and T of the tire is not particularly limited. What is necessary is just to comprise so that it may differ. Therefore, the rubber mass in any part among the parts such as the wing tip, the side rubber, the liner, and the carcass covering rubber constituting the rubber GA and GB may be varied on the left and right. In order to change the mass of the rubber, a material for changing the mass is added to the rubber composition without changing the volume (volume) of the rubber so as not to affect other tire performances. Good.

  Thereby, the left and right amplitudes in the regions T and T that become the antinodes of the vibration mode can be changed from each other, and road noise in the frequency range of 200 to 400 Hz can be efficiently reduced. In addition, while increasing the mass on the left and right sides of the tire, decreasing the mass on the other side offsets the increase and decrease of the rubber mass on the left and right, so there is no increase or decrease in the total tire mass. Further, deterioration of other tire performances such as riding comfort and rolling resistance can be prevented.

  In the present invention, at least one of barium sulfate, titanium oxide, and zinc oxide is blended with the rubber GA having a high mass, and a foaming agent is blended with the rubber GB having a low mass. Thereby, the increase / decrease in the mass of the rubber | gum in the right-and-left area | regions T and T can be canceled efficiently.

  The masses GA and Gb of the rubber GA and GB described above refer to the total mass of the rubber in the regions T and T extending from the both end portions 5a and 5a of the belt layer 5 to the tire maximum width positions 6 and 6, respectively. In this case, the rubber corresponding to the regions T and T is taken out from the vulcanized tire and the total mass is measured, and then the value obtained by subtracting the mass of the carcass cord, which is a non-rubber component, from the measured value. Therefore, the case where the above-described mass relationship is reversed between the left and right is allowed between the parts constituting the rubber GA and GB.

Furthermore, in the present invention, the ratio Ga / Gb between the mass Ga of the rubber on the higher mass side and the mass Gb of the rubber on the lower mass side is 1.2 to 2.0, preferably 1.4 to 1.8. It is adjusted so that If Ga / Gb is less than 1.2, the effect of reducing road noise cannot be obtained sufficiently, and if it exceeds 2.0, the left and right mass balances are so different that riding comfort and uneven wear resistance are deteriorated and steering stability is deteriorated. Will drop.

Further, in the pneumatic radial tire 1 of the present invention, it is preferable to form the recess 7 on the tire outer wall at the tire maximum width position 6 on the rubber GA side where the mass is high, from the viewpoint of securing running stability during high speed running. Thereby, the rigidity balance in the tire radial direction on the left and right is well maintained, and uneven wear resistance and riding comfort can be improved at the same time. The recessed part 7 is good to comprise by the hollow of a cross-sectional substantially circular arc shape which is 1-10 mm in width and 0.5-3 mm in depth. And it is good to form this hollow continuously in a tire peripheral direction.

  The pneumatic radial tire 1 of the present invention may form asymmetric patterns with different groove area ratios on the left and right sides of the tire equator on the surface of the tread portion. When an asymmetric pattern with different right and left groove area ratios is formed in the tread portion in this way, a rubber GA having a high mass is disposed on the side having a large groove area ratio, and a rubber GB having a low mass on the side having a small groove area ratio is disposed. It is good to arrange. This makes it possible to equalize the positions of the center of gravity on the left and right sides of the tire in a well-balanced manner, and to ensure good high-speed durability by equalizing the rising of the tread portion on the left and right during high-speed running.

  Furthermore, when the pneumatic radial tire 1 of the present invention is mounted on the vehicle, the rubber GA side having a high mass is mounted on the vehicle inner side, and the rubber GB side having a low mass is mounted on the vehicle outer side. This compensates for the asymmetry of the rim weight (the weight on the outside is higher than that on the inside of the vehicle), so that the ground contact area on the inside of the vehicle during turning can be secured. Can be secured.

  As described above, in the pneumatic radial tire of the present invention, the mass of rubber in the left and right regions from the both ends of the belt layer to the tire maximum width position is higher on the one side than the peripheral rubber, and on the other side By making it lower than rubber, the road noise in the frequency range of 200 to 400 Hz is reduced while suppressing the increase in the total mass of the tire, without causing any deterioration in performance due to the increase in tire weight. In addition, since road noise can be reduced, it can be widely applied as a high-frequency noise reduction tire.

  Conventional tire size is 225 / 45ZR17, tire structure is shown in FIG. 1, and the sum of the rubber masses Ga and Gb (Ga + Gb) in the left and right regions T and T is the same, and the left and right rubber masses Ga and Gb are made equal. A tire (conventional example) and tires of the present invention (Examples 1 to 3) in which the ratio Ga / Gb of the left and right rubber masses Ga and Gb was changed as shown in Table 1 were produced.

  These four types of tires were evaluated for ride comfort, uneven wear resistance and road noise by the following test methods, and the results are also shown in Table 1. The higher the number, the better.

[Evaluation of ride comfort]
Each tire is filled with air pressure of 230 kPa, mounted on the front and rear wheels of a domestic 2000cc vehicle so that the side with the higher rubber mass is on the inside of the vehicle, and a test course consisting of a rough road is run at an average speed of 50 km / h, Sensory evaluation was performed by three skilled test drivers. The results were averaged and displayed as an index with the conventional example being 100.

[Evaluation of uneven wear resistance]
Each tire is filled with an air pressure of 230 kPa, mounted on the front and rear wheels of a domestic 2000cc vehicle so that the side with the higher rubber mass is the inside of the vehicle, traveled on a general road mainly composed of asphalt roads for 5000 km, The occurrence state (size, depth) of uneven wear on the tread surface was measured. The reciprocal number was used for evaluation of uneven wear resistance, and the result was displayed as an index with the conventional example as 100.

[Evaluation of road noise]
Each tire is filled with air pressure 230 kPa, mounted on the front and rear wheels of a domestic 2000cc vehicle so that the side with the higher rubber mass is inside the vehicle, while running a test course consisting of rough roads at an average speed of 50 km / h, The sound pressure (decibel) in the 200 to 400 Hz region was measured with a sound collecting microphone attached to the backrest of the driver's seat. The reciprocal number was used to evaluate road noise, and the result was displayed as an index with the conventional example being 100.

  From Table 1, the tires of the present invention (Examples 1 to 3) reduce road noise in the 200 to 400 Hz region without substantially reducing ride comfort and uneven wear resistance compared to conventional tires. You can see that

It is sectional drawing which shows the pneumatic radial tire which consists of embodiment of this invention. It is a graph which shows the sound pressure level of the road noise accompanying the vibration of a tire.

Explanation of symbols

1 Pneumatic radial tire 2 Bead part 3 Carcass layer 4 Tread part 5 Belt layer 5a End part of belt layer 6 Tire maximum width position 7 Recess T region GA, GB Rubber Ga, Gb Mass

Claims (5)

In a pneumatic radial tire in which at least one carcass layer is mounted between a pair of left and right bead portions, and a belt layer is disposed on the outer periphery of the carcass layer in a tread portion,
In the left and right regions from the both ends of the belt layer to the tire maximum width position, rubber having a higher mass than the periphery in the tire radial direction is arranged in one region , and the mass in the other region from the periphery in the tire radial direction is arranged. lower by placing the rubber having a mass in the region of the mass distribution at different Rutotomoni, side where the mass and mass Ga in the region of the mass was disposed a high rubber side placed the lower rubber in left and right tires A pneumatic radial tire having a ratio Ga / Gb to Gb of 1.2 to 2.0 .   The pneumatic radial tire according to claim 1, wherein at least one of barium sulfate, titanium oxide, and zinc oxide is blended with the high-mass rubber, and a foaming agent is blended with the low-mass rubber. The pneumatic radial tire according to claim 1 or 2, wherein a concave portion is formed at a maximum tire width position on the higher mass side. Forming an asymmetric pattern with different groove area ratios on the left and right sides of the tire equator in the tread portion, disposing rubber having a high mass on the side where the groove area ratio is large, and placing the mass on the side where the groove area ratio is small The pneumatic radial tire according to claim 1, 2 or 3, wherein a low rubber is arranged. The pneumatic radial tire according to claim 1, 2, 3 or 4 , wherein the side on which the high-mass rubber is arranged is attached to the inside of the vehicle, and the side on which the low-mass rubber is arranged is attached to the outside of the vehicle. .

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