JP5140334B2 - Pneumatic tire - Google Patents

Description

  The present invention provides a tread tread surface with a circumferential groove extending continuously in the circumferential direction, an air chamber that opens to the land surface at a position away from the circumferential groove, and a narrowed neck that communicates the air chamber with the circumferential groove. In particular, the present invention relates to a tire that can gradually change the tread pattern over time without sacrificing the effect of reducing air column resonance noise.

With the recent quietness of vehicles, the ratio of tire noise to automobile noise has become relatively large, so reducing tire noise has become a major issue. Above all, tire noise around 1000 Hz, which is easily heard by humans, is a major cause of noise outside the vehicle, and this noise is expected to be promptly taken from the viewpoint of environmental problems.
By the way, the tire noise of about 800 to 1200 Hz may be generated by air column resonance caused by resonance of the air column defined by the circumferential groove and the road surface in the tire contact surface. In general, in order to suppress such air column resonance, the tread tread has a circumferential groove extending continuously in the circumferential direction, and an air chamber that opens to the land surface at a position away from the circumferential groove. A pneumatic tire has been proposed in which a resonator including a constricted neck that communicates the air chamber with the circumferential groove is disposed in a land portion (see, for example, Patent Document 1). It is said that air column resonance can be reduced by resonance.

JP 2001-191734 A

  However, in the prior art shown above, the constriction neck is configured to have a certain depth over the entire length from the circumferential groove to the air chamber, and in this case, it becomes shallow as the wear of the tire progresses. Since the initial narrowing neck is shallower than the circumferential grooves and air chambers, it disappears suddenly at a certain point, leaving only the circumferential grooves and air chambers. The change causes an abrupt change in performance and is not preferable.

  The present invention has been made in view of such a problem, and provides a tire capable of making a change in a tread pattern over time without sacrificing an effect of reducing air column resonance. With the goal.

According to the present invention, a tread surface is provided with a circumferential groove extending linearly and continuously in the circumferential direction, and an air chamber opening on the land surface at a position away from the circumferential groove, and the air chamber communicated with the circumferential groove. In the tire in which the resonator including the narrowed neck to be disposed is disposed in the land portion, the depth of the narrowed neck is changed in the length direction. In this case, it is preferable that the depth of the narrowed neck is continuously changed from the circumferential groove to the air chamber.

  According to the present invention, since the depth of the stenosis neck is changed in the length direction, it is possible to prevent the entire stenosis neck from disappearing rapidly at a certain point and to suppress a rapid change in the tread pattern. And if the change in the depth of the stenosis neck changes continuously from the circumferential groove to the air chamber, the extinction region of the stenosis neck can be gradually expanded, so the change in the tread pattern Can be made more gradual.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a tire ground contact surface in a state in which a pneumatic tire according to an embodiment of the present invention is assembled to an applicable rim, filled with a maximum air pressure and loaded with a mass corresponding to a maximum load capacity, The tire has a circumferential groove 1 continuously extending in the circumferential direction on a tread surface, an air chamber 3 that opens in the circumferential groove 1 and opens on a surface of a land portion 2 that is separated from the circumferential groove 1, and an air chamber 3. A resonator 5 including a constricted neck 4 communicating with the circumferential groove 1 is disposed in the land portion.

  Here, the applicable rim refers to the rim specified in the following standards, the maximum air pressure refers to the air pressure defined in accordance with the maximum load capacity in the following standards, and the maximum load capacity refers to the following The maximum mass allowed to be loaded on a tire by standard.

  The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, “THE TIRE AND RIM ASSOCIARION INC. YEAR BOOK” in the United States, “European Tire and Rim Technical Organization, Japan” .

The feature of the present invention is that the depth of the constriction neck 4 is changed in the length direction, that is, the direction along the center line LN connecting the midpoints in the width direction of the resonator. Each of FIG. 5 has an air chamber having a length of L ₁ and a width of W ₁ and a narrowed neck having a length of L ₂ and a width of W ₂ , and the opening shape to the tread surface is the same. However, FIG. 3 is a longitudinal sectional view illustrating four resonators having different length direction distributions (changes) of the stenosis necks, and the resonator 5 of the first embodiment shown in FIG. 2. the two parts 14a depth varies stepwise, it has a narrowed neck 4 consisting 14b, in the illustrated case, narrowed neck 4 has a circumferential groove portion 14a depth d _1, a depth d ₁ and is composed of a deeper d ₂ in the gas chamber side portion 14b, also resonators 5A of the second embodiment shown in FIG. 3, depth, of the circumferential groove side from d ₃ of the air chamber side d _It has a constriction neck 4A that continuously deepens up to _four .

In addition to these embodiments, as shown in FIG. 4, a resonator 5B formed such that the lengthwise center of the constriction neck 4B is shallower (or deeper) than both sides thereof, and FIG. as shown, it is possible depth d ₅ of the circumferential groove side to illustrate the resonator 5C, or the like having a deep narrowed neck 4C than the depth d ₆ of the air chamber side. Note that the resonator in the conventional tire has a narrowed neck 94 having a constant depth d as shown in the longitudinal sectional view of FIG.

  In the present invention, the tread pattern (that is, the tread surface of the groove portion) is changed over time by using the tire by changing the length of the narrowed necks 4, 4A, 4B, and 4C in the length direction as in the above example. The change in the tread pattern will be described with reference to the following example.

  The tire of the first embodiment shown in FIG. 2 is taken as Example 1, the tire of the second embodiment shown in FIG. 3 is taken as Example 2, and an initial tread is compared with these examples. As a comparative example (see FIG. 6), a conventional tire having a resonator in which the shape of the opening to the tread is exactly the same as in Example 1 and Example 2 and the depth of the narrowed neck is uniform over the length direction. For these tires, the tread pattern at each wear stage (opening shape to the tread surface of the groove portion) was drawn by simulation. 7 shows the results of Example 1, FIG. 8 shows the results of Example 2, and FIG. 9 shows the results of Comparative Example.

In each of the resonators of Examples 1 and 2 and the comparative example, the air chamber width W ₁ is 10 mm, the air chamber length L ₁ is 25 mm, the stenosis neck width W ₂ is 2 mm, and the stenosis neck length. L ₂ was 10 mm. Also, for these depths, examples depth d ₁ of 1, d ₂ (see FIG. 2), the depth of the Example 2 d _3, d ₄ (see FIG. 3), and the depth of Comparative Example d (see FIG. 2) is shown in Table 1.

  7-9, (a) is the initial tread pattern (when the degree of wear is 0%), (b) is the tread pattern when the degree of wear is 30%, and (c) is the degree of wear of 50%. (D) shows the tread pattern when the degree of wear is 70%. In addition, the abrasion degree in the above is the value which expressed the ratio with respect to the initial groove depth of the difference of the initial groove depth of the circumferential groove 1 and the groove depth at the time of abrasion with a percentage.

  In the comparative example, as is apparent when comparing FIG. 7 (b) and FIG. 7 (c), the stenosis neck 94 disappears at any time between 30% and 50% of the degree of wear. On the other hand, in the first embodiment, as shown in FIG. 5C, only a part of the stenosis neck 4 disappears, and the stenosis neck as shown in FIG. It reaches the complete disappearance stage. In the second embodiment, the change over time of the opening shape of the narrowed neck 4A on the tread surface is made more gradual, and it passes through the partial wear stage of the narrowed neck 4A when the wear degree is 50% and 70%. It can be seen that it will completely disappear.

  The tire size in the above example was 195 / 65R15. In addition, it is said that the resonance noise reduction effect by the resonator should be effective up to the point when the wear level is up to 30%. In any case, the resonator functions sufficiently until the wear level is 30%. Yes.

  In addition, although the result of having measured the noise in the initial stage about these tires is shown in Table 1, there is not a big difference in these resonance noise reduction effects so that Table 1 clearly shows, Therefore Example 1, Example It can be seen that the tire of No. 2 can have a gradual change in the tire pattern over time without sacrificing the resonance noise reduction effect as compared with the tire of the comparative example.

  Note that the noise reduction method in Table 1 is to measure the noise by mounting a tire of the above size on a 6JJ rim, filling it with 210kPa air pressure, and using an indoor drum tester under a load of 4.4kN for 80km. Roll the load at a speed of / h, measure the side sound of the tire at this time according to the conditions specified in JASO C606, and obtain the overall value of the band with a center frequency of 800-1000Hz-1250Hz in 1/3 octave band It was. The evaluation results are shown in Table 1 as a difference (dB) in decibels as a resonance reduction effect for a tire having no resonator (the resonator portion of the tire pattern shown in FIG. 1 is landed). .

1 is a plan view showing a ground contact surface of a tire according to an embodiment of the present invention. It is sectional drawing which shows the resonator of the tire of 1st embodiment. It is sectional drawing which shows the resonator of the tire of 2nd embodiment. It is sectional drawing which shows the resonator of the tire of other embodiment. It is sectional drawing which shows the resonator of the tire of other embodiment. It is sectional drawing which shows the resonator of the tire of a comparative example. FIG. 3 is a schematic diagram showing a change with time of the tread pattern of the tire of Example 1; FIG. 6 is a schematic diagram showing a change over time in a tread pattern of a tire of Example 2. It is a schematic diagram which shows the time-dependent change of the tread pattern of the tire of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circumferential groove 2 Land part 3 Air chamber 4, 4A, 4B, 4C Stenosis neck 5, 5A, 5B, 5C Resonator 10 Tire contact surface 14a Circumferential groove side part of stenosis neck 14b Air chamber side part of stenosis neck

Claims (5)

A tread surface is provided with a circumferential groove extending linearly and continuously in the circumferential direction, and an air chamber that opens to the surface of the land portion at a position away from the circumferential groove, and a narrowing neck that communicates the air chamber with the circumferential groove, A tire in which a resonator comprising the above is disposed in a land portion, wherein a depth of the narrowed neck is changed in a length direction thereof.   The tire according to claim 1, wherein a depth of the narrowed neck is continuously changed from the circumferential groove to the air chamber. The tire according to claim 1 or 2, wherein the circumferential groove communicating with the resonator does not communicate with other circumferential grooves and tread ends. The tire according to any one of claims 1 to 3, wherein a depth at a central portion in the length direction of the narrowed neck is shallower than a depth at both lengthwise sides of the narrowed neck. The tire according to any one of claims 1 to 3, wherein the narrowed neck has a depth on the circumferential groove side that is deeper than a depth on the air chamber side.

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