JP6076127B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire with reduced air column resonance caused by circumferential grooves extending in the tire circumferential direction.

It is generally known that air column resonance is generated by so-called air column resonance, in which an air column defined by a circumferential groove extending in the tire circumferential direction and a road surface in the ground contact surface resonates. The frequency of the air column resonance sound is 800 to 1200 Hz in a general passenger car, and the frequency band is wide and the peak sound pressure level is high.
In addition, human hearing is sensitive in a frequency band around 1000 Hz, as indicated by a frequency correction characteristic called A characteristic that reflects human auditory sensitivity characteristics, and this reduction in air column resonance is quiet in the passenger compartment. It is very effective for improving the performance and reducing the noise near the road.

で表されることが分かっている。 In order to suppress such air column resonance, Patent Document 1 discloses that at least one circumferential groove extending in the tire circumferential direction on the tread surface of the tire and one end opened to the circumferential groove and the other end. Has been proposed that includes a branch groove that functions as a so-called side-branch resonator that ends in the land. As shown in FIG. 1A, when the length of the side branch type resonator 4 opening in the circumferential groove 2 is l and the speed of sound is c, the frequency f to be reduced is:

It is known that

で表されることが分かっている。 Further, Patent Document 2 proposes to reduce the air column resonance by using a so-called Helmholtz resonator, which is composed of a narrowed section having a small cross-sectional area and an air chamber section having a large cross-sectional area. Yes.
In this case, as shown in FIG. 1 (b), the length of the narrow groove portion plus the opening end correction amount is l, the cross sectional area of the narrow groove portion is S, the volume of the air chamber portion is V, and the sound velocity is c. Then, the frequency f to be reduced is

It is known that

で表されることが分かっている。 Alternatively, instead of the Helmholtz type resonator as described above, as shown in FIG. 1 (c), pipes having different cross-sectional areas having constant cross-sectional areas S1 and S2 are connected in the length direction. A stepped tube resonator can also be applied. In this case, if the lengths of the respective pipelines plus the opening end correction amount are 11 and 12 and the sound speed is c, the resonance frequency f is

It is known that

International Publication No. 2004/1037737 Pamphlet JP 2008-213596 A

Patent Document 2 described above discloses that the wear performance is improved by making the length in the tire circumferential direction of the air chamber portion of the Helmholtz resonator longer than the length in the tire width direction. However, the circumferential rigidity of the land portion surrounded by the air chamber portion, the narrowed portion, and the circumferential groove is lowered, and there is a possibility that sufficient braking performance cannot be ensured.
Accordingly, an object of the present invention is to provide a pneumatic tire that reduces air column resonance and ensures sufficient braking performance.

The gist of the present invention is as follows.
(1) At least two circumferential grooves extending in the tire circumferential direction are formed on the tread with the tire equatorial plane interposed between the vehicle mounting inner side and the vehicle mounting outer side, and a plurality of ribs are formed by the circumferential groove. In pneumatic tires with asymmetrical patterns with land sections,
The negative rate of the vehicle wearing inner region is higher than the negative rate of the vehicle wearing outer region,
The circumferential groove ruri blanking-like land portion be adjacent, resonator having a recessed air chamber toward the inner side in the tire radial direction, a constriction communicating with the air chamber portion and said circumferential groove, a is Multiple formed,
Each of the resonators is disposed only in a rib-like land portion on the vehicle-mounted outer side of a circumferential groove that communicates with a narrowed neck of each resonator,
The air chamber part has a tire circumferential direction length longer than a tire width direction length,
The narrowed portion is inclined at 60 ° ± 10 ° with respect to the tire circumferential direction.
A pneumatic tire characterized by that.

(2) The plurality of resonators include a first resonator having a first circumferential length and a second resonator having a second circumferential length shorter than the first circumferential length. The pneumatic tire according to (1) above.

(3) The pneumatic tire according to (2), wherein the width of the first constricted portion of the first resonator is larger than the width of the second constricted portion of the second resonator.

(4) The air according to (2) or (3), wherein a depth of the first constriction portion of the first resonator is larger than a depth of the second constriction portion of the second resonator. tire.

It is a figure which shows the example of a resonator. It is a figure which shows the tread pattern which concerns on 1st Example of the pneumatic tire of this invention. It is a figure for demonstrating the effect of this invention. It is a figure which shows the tread pattern which concerns on 2nd Example of the pneumatic tire of this invention.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings. In addition, since the internal reinforcement structure of a tire is the same as that of a general pneumatic tire, the description is abbreviate | omitted.
FIG. 2 is a view showing a tread pattern according to the first embodiment of the pneumatic tire of the present invention. The pneumatic tire has an asymmetric tread pattern. Specifically, two circumferential grooves 2a and 2b extending in the tire circumferential direction are formed on the tread on the inner side of the vehicle with the tire equatorial plane CL interposed therebetween, and one circumferential direction extending in the tire circumferential direction on the outer side of the vehicle mounting. Directional grooves 2c are formed. The rib-like land portions 3a to 3d are partitioned by these circumferential grooves 2a to 2c.

Here, the negative rate of the vehicle mounting inner region is higher than the negative rate of the vehicle mounting outer region.
In addition, among the rib-like land portions 3a and 3b adjacent to the circumferential groove 2a, a plurality of resonators 4 are formed on the rib-like land portion 3b located outside the vehicle mounting. Each resonator 4 has an air chamber portion 4a that is recessed toward the inner side in the tire radial direction, and a narrowed portion 4b that communicates with the air chamber portion 4a and the circumferential groove 2a. Similarly, a plurality of resonators 4 are formed in a rib-like land portion 3c outside the vehicle mounted adjacent to the circumferential groove 2b. Each resonator 4 includes an air chamber portion 4a that is recessed toward the inside in the tire radial direction. And a narrowed portion 4b communicating with the air chamber portion 4a and the circumferential groove 2b. In addition, a plurality of resonators 4 are formed in a rib-like land portion 3d outside the vehicle mounted adjacent to the circumferential groove 2c, and each resonator 4 includes an air chamber portion 4a that is recessed toward the inside in the tire radial direction, A narrow portion 4b communicating with the air chamber portion 4a and the circumferential groove 2c.
The air chamber portion 4a has a tire circumferential direction length L1 longer than a tire width direction length L2. Further, the narrowed portion 4b is inclined at θ = 60 ° ± 10 ° with respect to the tire circumferential direction.

Hereinafter, the function and effect of the present invention will be described.
Generally, a pneumatic tire is often mounted on a vehicle with a negative camber attached. Then, the contact area with respect to the road surface increases in the vehicle mounting inner region than in the vehicle mounting outer region. Here, the wet performance can be improved by setting the negative rate of the vehicle mounting inner region higher than the negative rate of the vehicle mounting outer region.
Further, in a state where a negative camber is applied to the pneumatic tire, the vehicle mounting inner region has a higher contact pressure than the vehicle mounting outer region. Therefore, the rigidity of the rib-shaped land portion is improved by providing the resonator 4 in the rib-shaped land portion 3b outside the vehicle mounting rather than providing the resonator 4 in the rib-shaped land portion 3a inside the vehicle mounting of the circumferential groove 2a. Reduction can be suppressed. Therefore, by providing the resonator 4 in the rib-like land portions 3b to 3d outside the vehicle mounted in the circumferential grooves 2a to 2c, the air column resonance noise caused by the circumferential grooves 2a to 2c is reduced, and the rib shape is provided. The decrease in rigidity of the land is suppressed.

When the edge component extending in the tire width direction at the edge of the air chamber portion 4a is long, the braking force acting in the tire circumferential direction is increased, and the wear of the rib-shaped land portion is increased. By making the length L1 in the direction longer than the length L2 in the tire width direction, the generation of braking force can be suppressed and the amount of wear can be reduced. However, when the edge component extending in the tire circumferential direction at the edge of the air chamber portion 4a is lengthened, the block-shaped land portion R surrounded by the air chamber portion 4a, the narrowed portion 4b, and the circumferential groove has a tire circumference. It will extend long in the direction. Then, the circumferential rigidity of the land portion R is lowered, causing a decrease in grounding property due to deformation in the grounding surface, and there is a concern that a stopping distance during braking becomes long.
Accordingly, by inclining the narrowed portion 4b at θ = 60 ° ± 10 ° with respect to the tire circumferential direction, the braking performance is improved as compared with the case where the narrowed portion 4b is tilted at less than θ = 50 °. be able to.
In the case of FIG. 3A in which θ = 45 °, when the corner portion Rk of the block-like land portion R adjacent to the constricted portion 4b enters the ground plane, a force is applied in the direction of the arrow in the figure, and this corner portion. Rk is pushed to the land R side and is caught. When this is shown in a circumferential cross-sectional view, the state shown in FIG. 3B is changed to the state shown in FIG. 3C, and the portion adjacent to the corner Rk is lifted from the ground plane. As a result, the grounding property is insufficient.
In the present invention, by increasing the angle of the corner portion Rk of the block-shaped land portion R, force is applied not only to the corner portion Rk but also to the land portion adjacent to the corner portion Rk. In addition, it is possible to increase the ground contact within the ground contact surface and maintain the braking performance.

  In the tread pattern of FIG. 2, it is preferable that the groove widths of the circumferential grooves 2 a, 2 b, and 2 c increase from the vehicle mounting inner side toward the vehicle mounting outer side. With this configuration, the rigidity of the rib-like land portions 3a, 3b, and 3c can be sufficiently ensured while improving the drainage performance in the vehicle mounting inner region where the two circumferential grooves 2a and 2b are formed. . Similarly, in the vehicle mounting outer region where only one circumferential groove 2c is formed, it is possible to achieve both the rigidity block rigidity and the drainage performance of the rib-like land portions 3c and 3d.

FIG. 4 is a view showing a tread pattern according to a second embodiment of the pneumatic tire of the present invention. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
Each of the rib-like land portions 3b to 3d includes a first resonator 41 having a first circumferential length L41 and a second resonator 42 having a second circumferential length L42 shorter than the first circumferential length L41. Is formed.
By adopting so-called pitch variations in which the interval (pitch) of the repeating pattern along the tire circumferential direction of the tread pattern is not one type but multiple types (two types in the illustrated example), the noise during driving is converted into white noise. Can be reduced.
In the illustrated example, the circumferential length of the first air chamber portion 41a is longer than the circumferential length of the second air chamber portion 42a while the lengths of the first constriction portion 41b and the second constriction portion 42b are made equal. Thus, although the first circumferential length L41 is longer than the second circumferential length L42, the lengths of the first constricted portion 41b and the second constricted portion 42b can be changed.

Further, it is preferable that the width W41b of the first constricted portion 41b is larger than the width W42b of the second constricted portion 42b. Furthermore, it is preferable that the depth D41b of the first constricted portion 41b is larger than the depth D42b of the second constricted portion 42b.
With these configurations, the rigidity of the land portion R2 adjacent to the second constriction portion 42b is higher than the rigidity of the land portion R1 adjacent to the first constriction portion 41b, the deformation of the land portion R2 is suppressed, and the grounding property is deteriorated. The braking performance can be improved.

The present invention is not limited to the embodiments described above.
For example, in the illustrated example, the circumferential grooves 2a to 2c extend linearly in the tire circumferential direction, but the circumferential grooves 2a to 2c may extend in a zigzag manner in the tire circumferential direction.
In FIG. 2, the resonator 4 formed in the rib-like land portion 3 b and the resonator 4 formed in the rib-like land portion 3 c are arranged side by side in the tire width direction, but the resonator 4 is arranged in the tire width direction. It can also be shifted. In this case, the edge components in the width direction of the resonators 4 are not grounded at the same time, which is preferable because pattern noise can be reduced.
Moreover, although the resonator 4 was formed in the rib-shaped land part on the vehicle mounting outer side adjacent to the circumferential groove, it can also be formed on the rib-shaped land part on the outer side of the vehicle mounting. For example, in the configuration of FIG. 2, the resonator 4 formed in the rib-like land portion 3c is opened in the circumferential groove 2c, and the rib-like land portions 3c and 3d on both sides of the circumferential groove 2c are inserted into the circumferential groove 2c. It is also possible to provide a resonator 4 that reduces the air column resonance sound.

Examples of the present invention will be described below, but the present invention is not limited thereto.
Invention tires and comparative tires were prototyped and their braking performance was evaluated. Each test tire (tire size: 195 / 65R15) has the tread pattern shown in FIG. 4, and as shown in Table 1, the length L41b, the width W41b, the depth D41b, and the inclination angle of the first constricted portion 41b. θ41, the length L42b, the width W42b, the depth D42b, and the inclination angle θ42 of the second constricted portion 42b are changed.

(Evaluation of braking performance)
After attaching each test tire to the applicable rim and applying the specified internal pressure, attach it to the vehicle (four wheels of a normal passenger car) and apply the normal load (maximum load in the applicable size and ply rating specified in JATMA YEAR BOOK) And run the test course.
The braking distance from a speed of 100 km / h until full braking was applied to the stationary state was measured. The results are shown as indices in Table 1 with the braking distance of Comparative Example 1 being 100. In addition, it shows that it is excellent in performance, so that an index | exponent is small.

  From Table 1, it can be seen that the inventive tires are able to ensure good braking performance.

2 circumferential groove 3 rib-like land portion 4 resonator 41 first resonator 42 second resonator 4a air chamber portion 41a first air chamber portion 42a second air chamber portion 4b constriction portion 41b first constriction portion 42b second constriction Part

Claims (4)

At least two circumferential grooves extending in the tire circumferential direction are formed on the tread with the tire equatorial plane sandwiched between the vehicle mounting inner side and the vehicle mounting outer side, and a plurality of rib-like land portions are formed by the circumferential groove. In a pneumatic tire with a compartmentalized asymmetric pattern,
The negative rate of the vehicle wearing inner region is higher than the negative rate of the vehicle wearing outer region,
The circumferential groove ruri blanking-like land portion be adjacent, resonator having a recessed air chamber toward the inner side in the tire radial direction, a constriction communicating with the air chamber portion and said circumferential groove, a is Multiple formed,
Each of the resonators is disposed only in a rib-like land portion on the vehicle-mounted outer side of a circumferential groove that communicates with a narrowed neck of each resonator,
The air chamber part has a tire circumferential direction length longer than a tire width direction length,
The narrowed portion is inclined at 60 ° ± 10 ° with respect to the tire circumferential direction.
A pneumatic tire characterized by that.   The plurality of resonators includes a first resonator having a first circumferential length and a second resonator having a second circumferential length shorter than the first circumferential length. The pneumatic tire according to 1.   The pneumatic tire according to claim 2, wherein a width of the first constriction portion of the first resonator is larger than a width of the second constriction portion of the second resonator.   The pneumatic tire according to claim 2 or 3, wherein a depth of the first constriction portion of the first resonator is larger than a depth of the second constriction portion of the second resonator.

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