阅读说明：本技术 充气轮胎 (Pneumatic tire ) 是由 富田达也 于 2018-12-10 设计创作，主要内容包括：一种轮胎,其在胎面接地面具有多个陆部,该多个陆部被沿轮胎周向连续地延伸的周向主槽至少划分了轮胎宽度方向一侧,在所述多个陆部中的位于相对于轮胎赤道面而言的车辆安装内侧半部的内侧陆部具备内侧共鸣器,该内侧共鸣器包含在该内侧陆部内终止的第1副槽和将所述第1副槽与所述周向主槽连通的第1支槽,其中,在所述第1支槽与所述第1副槽相邻地设有隐藏槽部,该隐藏槽部的胎面接地面处的开口宽度小于槽底的槽宽。(A tire having a plurality of land portions on a tread contact surface, the land portions being divided at least on one side in a tire width direction by a circumferential main groove extending continuously in a tire circumferential direction, an inner resonator including a1 st sub-groove terminating in the inner land portion and a1 st sub-groove communicating the 1 st sub-groove with the circumferential main groove being provided in an inner land portion of the land portions located in a vehicle-mounted inner half with respect to a tire equatorial plane, wherein a hidden groove portion having an opening width at a tread contact surface smaller than a groove width of a groove bottom is provided in the 1 st sub-groove adjacent to the 1 st sub-groove.)

1. A tire having, in a tread contact surface, a plurality of land portions partitioned at least on one side in a tire width direction by a circumferential main groove extending continuously in a tire circumferential direction, an inner resonator including a1 st sub-groove terminating in a1 st of the plurality of land portions and a1 st sub-groove communicating the 1 st sub-groove with the circumferential main groove being provided in an inner land portion of a vehicle-mounted inner half portion with respect to a tire equatorial plane,

and a hidden groove part is arranged at the 1 st branch groove and adjacent to the 1 st auxiliary groove, and the opening width of the tread contact surface of the hidden groove part is smaller than the groove width of the groove bottom.

2. The tire according to claim 1, wherein,

an outer resonator including a2 nd sub-groove terminating in the outer land portion and a2 nd sub-groove communicating the 2 nd sub-groove with the circumferential main groove is provided in an outer land portion of the plurality of lands on a vehicle-mounted outer half with respect to a tire equatorial plane, and a tire circumferential length of the outer resonator at the tread contact surface is smaller than a tire circumferential length of the inner resonator.

3. The tire according to claim 1 or 2,

the volume of the 2 nd sub-groove of the outer resonator is smaller than the volume of the 1 st sub-groove of the inner resonator, and the number of the outer resonators arranged in the entire tire circumferential direction is larger than the number of the inner resonators arranged in the entire tire circumferential direction.

4. A tire according to any one of claims 1 to 3,

the tire includes at least two circumferential main grooves, and a groove width of the circumferential main groove on the innermost side of the vehicle mounting is largest among the circumferential main grooves.

5. A tire according to any one of claims 2 to 4,

the hidden groove portion of the 1 st branch groove and the 2 nd sub groove overlap in the tire width direction.

6. A tire according to any one of claims 1 to 5,

the groove depth of the 1 st sub groove is smallest at a portion adjacent to the 1 st branch groove.

Technical Field

The present invention relates to a pneumatic tire.

Background

In pneumatic tires, there is a demand for reducing noise during vehicle running and improving quietness. Various proposals have been made for such tires: an external noise such as air column resonance noise (generally observed at approximately 800Hz to 1200Hz in a typical passenger car) generated from a circumferential main groove provided in a tread contact surface of a tire is reduced by a resonator (so-called helmholtz resonator) including an air chamber and a narrowed neck portion (for example, patent document 1).

Disclosure of Invention

Problems to be solved by the invention

However, generally, when the helmholtz resonator is provided in the land portion of the tread, the rigidity distribution of the land portion tends to become uneven, and uneven wear tends to occur in the tread. Therefore, it is desirable to reduce air columnar resonance noise and also suppress uneven wear of the tread.

Accordingly, an object of the present invention is to provide a tire capable of reducing air columnar resonance noise and suppressing uneven wear of a tread.

Means for solving the problems

The tire of the present invention has a plurality of land portions partitioned at least on one side in the tire width direction by a circumferential main groove extending continuously in the tire circumferential direction in a tread contact surface, and an inner resonator including a1 st sub-groove terminating in the inner land portion and a1 st sub-groove communicating the 1 st sub-groove with the circumferential main groove is provided in an inner land portion of the plurality of land portions located in a vehicle-mounted inner half with respect to a tire equatorial plane, and is characterized in that a hidden groove portion having an opening width smaller than a groove width of a groove bottom is provided in the 1 st sub-groove adjacent to the 1 st sub-groove.

Here, in the present specification, the "vehicle-mounted inner half portion" and the "vehicle-mounted outer half portion" refer to half portions that become the outer side and the inner side of the vehicle in the tire width direction with respect to the tire equatorial plane when the tire is mounted on the vehicle.

In the present specification, the term "tread contact surface" refers to an outer peripheral surface of a tire that is assembled to a rim and filled with a predetermined internal pressure over the entire circumferential range of the tire and that comes into contact with a road surface when the tire rolls under a maximum load, and the term "tread contact end" refers to a tire width direction end of the tread contact surface.

In the present specification, the "opening width" and the "groove width" of each groove and the like refer to widths measured in a direction orthogonal to the extending direction of the groove in the following reference state. In the present specification, the "groove depth" and the "volume" of each groove also refer to the depth and volume measured in the following reference state. Hereinafter, unless otherwise specified, dimensions and the like of the respective elements such as the grooves are measured in a reference state.

In the present specification, the "reference state" refers to a state in which the tire is assembled to a rim, and a predetermined internal pressure is applied to the tire to cause no load.

The "Rim" is an industrial standard effective in an area where a Tire is produced and used, is STANDARDS MANUA L of JATMA (japan automobile Tire Association), STANDARDS MANUA L of The European Tire and Rim Technical Organization (ETRTO) in europe, is measurning Rim in STANDARDS MANUA L of The ETRTO, and Design Rim in The giar Rim of TRA (Tire Rim Association, The Tire and Rim Association, Inc.) or an application size described in The FUTURE (i.e., The "Rim" includes a current size and a size that The industrial standard will include in The FUTURE as well as a current size), and an example of The "size described in The FUTURE" may be listed as a "size that The industrial standard will include in The STANDARDS MANUA L2013 of The ETRTO, and an example of The" size described in The FUTURE "may be listed as a" full Tire L "in The STANDARDS MANUA L of The ETRTO, but The" maximum size of The air pressure "may correspond to a maximum air pressure of a predetermined load of The Tire (The" may be a maximum air pressure of The Tire).

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, uneven wear of the tread can be suppressed while reducing air columnar resonance noise.

Drawings

Fig. 1 is a partially developed view of a tread contact surface of a tire according to an embodiment of the present invention.

Fig. 2 is a partially enlarged view of the tread surface shown in fig. 1.

Fig. 3 is a sectional view taken along the line a-a shown in fig. 2.

Fig. 4 is a sectional view taken along the line b-b shown in fig. 2.

Fig. 5 is a sectional view taken along the line c-c shown in fig. 2.

Fig. 6 is a sectional view taken along the line d-d shown in fig. 2.

Detailed Description

Hereinafter, embodiments of the tire according to the present invention will be described by way of example with reference to the accompanying drawings.

Fig. 1 is a partially developed view showing a tread contact surface 2 of a tire 1 according to an embodiment of the present invention. Although a part of the illustration is omitted, the tire 1 of this embodiment includes a carcass having a radial structure extending annularly between bead portions, a belt disposed on the tire radial direction outer side of the carcass of the tread portion, and a tread rubber disposed on the tire radial direction outer side of the belt and forming a tread contact surface 2.

As shown in fig. 1, this tire 1 includes two inner circumferential main grooves 31a, 32a extending in a vehicle-mounted inner half HA (left side of the paper surface in fig. 1) of a tread surface 2 with respect to a tire equatorial plane C L, and two outer circumferential main grooves 31b, 32b extending in a vehicle-mounted outer half HB (right side of the paper surface in fig. 1) of the tread surface 2 with respect to a tire equatorial plane C L, the inner circumferential main grooves 31a, 32a and the outer circumferential main grooves 31b, 32b continuously and linearly extending in the tire circumferential direction, and further, the outer circumferential main grooves 31b, 32b have equal groove widths, the total groove width of the outer circumferential main grooves 31b, 32b is smaller than the total groove width of the inner circumferential main grooves 31a, 32a, the groove widths of the inner circumferential main grooves 31a, 32a on the tire ground end TE side are different from each other, the groove width of the inner circumferential main groove 32a on the tire ground end TE side is larger than the groove width of the inner circumferential main groove 31a on the tire equatorial plane C L side, and the largest main groove width is 3 in the circumferential main grooves.

In the tire 1, the circumferential main grooves 3 have the above-described extended form, and the widths of the circumferential grooves 3 have the above-described dimensional relationship, but in the tire of the present invention, the circumferential main grooves 3 may have a zigzag or wavy extended form, and the widths of the outer circumferential main grooves 31b, 32b may be made different from each other, or the widths of the inner circumferential main grooves 31a, 32a may be made different from each other, or the like.

As shown in fig. 1, the tread surface 2 has a plurality of (five in the present embodiment) land portions 4, and the land portions 4 are divided at least on one side in the tire width direction by (four in the present embodiment) circumferential main grooves 3 extending continuously in the tire circumferential direction.

More specifically, the tire 1 HAs a central land portion 41 divided by an inner circumferential main groove 31a and an outer circumferential main groove 31b adjacent to each other across a tire equatorial plane C L, an inner intermediate land portion 42a divided by two inner circumferential main grooves 31a, 32a, an outer intermediate land portion 42b divided by two outer circumferential main grooves 31b, 32b, an inner shoulder land portion 43a divided by a tread ground edge TE on the vehicle-mounting inner side (hereinafter also simply referred to as "tread ground edge TE") and an inner circumferential main groove 32a on the tread ground edge TE side, and an outer shoulder land portion 43b divided by a tread ground edge TE on the vehicle-mounting outer side (hereinafter also simply referred to as "tread ground edge TE") and an outer circumferential main groove 32b on the tread ground edge TE side, that is, in the tread ground contact surface 2, the central land portion 41 including a tire equatorial plane C L, two inner land portions (inner intermediate land portion 42a and inner shoulder land portion 43a) on the vehicle-mounting inner half HA, and two outer land portions (outer shoulder land portions 42b) on the vehicle-mounting outer half HA.

In addition, in this tire 1, each of the plurality of land portions 4 is a rib-shaped land portion extending continuously in the tire circumferential direction, but in the tire of the present invention, one or more land portions 4 of the plurality of land portions 4 may be a block-shaped land portion or the like.

Here, in the tire 1, the inner land portion (in the present embodiment, the inner intermediate land portion 42a) of the plurality of land portions 4 located in the vehicle-mounted inner half HA with respect to the tire equatorial plane C L includes an inner resonator 5 (in the illustrated example, a helmholtz type resonator).

More specifically, the inner resonator 5 includes a1 st sub-groove 51 terminating in the inner intermediate land portion 42a and a1 st sub-groove 52 communicating the 1 st sub-groove 51 with the circumferential main groove 3 (in the present embodiment, a1 st sub-groove 52a communicating the 1 st sub-groove 51 with the inner circumferential main groove 32a on the tread ground edge TE side and a1 st sub-groove 52b communicating the 1 st sub-groove 51 with the inner circumferential main groove 31a on the tire equatorial plane C L side).

In the inner resonator 5, the 1 st branch groove 52a is provided adjacent to the end 51Ea on one side in the tire circumferential direction of the 1 st sub-groove 51 (upper side in the paper surface in fig. 1), and the 1 st branch groove 52b is provided adjacent to the end 51Eb on the other side in the tire circumferential direction of the 1 st sub-groove 51 (lower side in the paper surface in fig. 1). that is, in this example, one end of the 1 st branch groove 52a opens into the inner circumferential main groove 32a on the tread ground end TE side, and the other end of the 1 st branch groove 52a opens into the end 51Ea on one side in the tire circumferential direction of the 1 st sub-groove 51. similarly, one end of the 1 st branch groove 52b opens into the inner circumferential main groove 31a on the tire equatorial plane C L side, and the other end of the 1 st branch groove 52b opens into the end 51Eb on the other side in the tire circumferential direction of the 1 st sub-groove 51.

In this way, in the inner resonator 5, the 1 st sub-groove 51 communicates with the two inner circumferential main grooves 31a, 32a by including the two 1 st branch grooves 52a, 52b, but in the tire of the present invention, the inner resonator may be configured to include only one 1 st branch groove, or may be configured to include two 1 st branch grooves but communicate with one inner circumferential main groove. In the tire of the present invention, the inner resonators may include three, four, or four or more 1 st grooves.

Further, in the tire of the present invention, the 1 st sub groove 52a, 52b may be provided adjacent to a portion of the 1 st sub groove 51 other than the tire circumferential direction end portions 51Ea, 51Eb, for example, adjacent to the tire circumferential direction central portion of the 1 st sub groove 51.

In the inner resonator 5, the 1 st sub-groove 51 has a larger groove volume than either of the two 1 st grooves 52a and 52b connected to the 1 st sub-groove 51. The opening area of the 1 st sub-groove 51 that opens in the tread surface 2 is larger than the opening area of either of the two 1 st sub-grooves 52a, 52b that connect to the 1 st sub-groove 51 that opens in the tread surface 2.

Fig. 2 is a partially enlarged view of the tread contact surface 2 shown in fig. 1, showing the acoustic resonator 5 and a peripheral portion of the acoustic resonator 5 in an enlarged manner. In the inner resonator 5, a hidden groove portion 52aH is provided in the 1 st branch groove 52 (one 1 st branch groove 52a in the present embodiment) adjacent to the 1 st sub-groove 51, and the opening width of the hidden groove portion 52aH in the tread contact surface 2 is smaller than the groove width of the groove bottom. In fig. 2, the groove wall hiding the groove portion 52aH is indicated by a dotted line.

More specifically, in the inner resonator 5, the 1 st branch groove 52a extends to have one bent portion, and is constituted by a1 st extending portion 52a1 extending substantially along the extending direction of the 1 st sub-groove 51 and a2 nd extending portion 52a2 extending in a direction different from the extending direction of the 1 st extending portion. The 1 st extending portion 52a1 is connected to the 1 st sub groove 51, and the 2 nd extending portion 52a2 is connected to the inner circumferential main groove 32 a. In the inner resonator 5, the hidden groove portion 52aH is provided only in the 1 st extending portion 52a 1. Further, the hidden groove portion 52aH is provided over the entire extension length of the 1 st extension portion 52a 1.

Although the 1 st groove 52a in the present embodiment extends so as to have one bent portion, the 1 st groove 52a may be formed so as to extend without a bent portion (straight or arcuate shape), or so as to extend so as to have two or more bent portions in the tire of the present invention.

In the tire 1, as shown in fig. 2, the hidden groove portion 52aH provided in the 1 st extending portion 52a1 of the 1 st branch groove 52a is provided continuously with the end region of the 1 st sub groove 51. That is, the hidden groove portion 51H is also provided in the peripheral region of the end 51Ea on the tire circumferential direction side of the 1 st sub-groove 51. However, in the tire of the present invention, the hidden groove portion may be provided in the entire region of the 1 st sub-groove 51, or only in the 1 st branch groove 52 a.

In the inner resonator 5, a portion where the opening width is constant in the tread surface 2 is the 1 st branch groove 52 a. In the tire of the present invention, when the opening width of the 1 st sub groove changes along the extending direction of the 1 st sub groove, a portion having an opening width smaller than 20% of the maximum width of the 1 st sub groove is set as the 1 st sub groove.

Fig. 3 to 5 are sectional views of the inner resonator 5. That is, fig. 3 is a sectional view taken along the line a-a of fig. 2, fig. 4 is a sectional view taken along the line b-b of fig. 2, and fig. 5 is a sectional view taken along the line c-c of fig. 2. More specifically, fig. 3 is a sectional view of a surface of the 1 st sub groove 52a orthogonal to the extending direction of the 1 st sub groove 52a, and fig. 4 and 5 are sectional views of a surface of the 1 st sub groove 51 orthogonal to the extending direction of the 1 st sub groove 51.

As shown in fig. 3, in the hidden groove portion 52aH of the 1 st branch groove 52a, the opening width W52aH at the tread contact surface 2 is smaller than the groove depth D52aH and smaller than the groove width W52aHB at the groove bottom 52 aHB.

Further, as shown in fig. 4, in the end region of the 1 st sub-groove 51 having the hidden groove portion 51H, the opening width W51H at the tread contact surface 2 is smaller than the groove depth D51H and smaller than the groove width W51HB at the groove bottom 51 HB.

Further, as shown in fig. 5, in the 1 st sub-groove 51 except for the end region having the hidden groove portion 51H, the opening width W51 at the tread contact surface 2 is smaller than the groove depth D51 and is greater than or equal to the groove width W51B at the groove bottom 51B.

Further, the opening width W51H at the tread surface 2 of the 1 st sub-groove 51 having the end region of the hidden groove portion 51H is smaller than the opening width W51 at the tread surface 2 of the 1 st sub-groove 51 except for the end region. Also, the groove depth D51H of the end region of the 1 st sub-groove 51 having the hidden groove portion 51H is larger than the groove depth D51 of the portion of the 1 st sub-groove 51 other than the end region.

In the tire 1, the groove depth of the 1 st branch groove 52a is the largest at the hidden groove portion 52aH, but the groove depth of the 1 st branch groove 52a may be constant in the tire of the present invention.

As shown in fig. 3, the hidden groove portion 52aH of the 1 st groove 52a is formed of an opening side portion 52aHa and a groove bottom side portion 52aHb in this order from the tread contact surface 2 side in a cross-sectional view of a surface orthogonal to the extending direction of the 1 st groove 52a, the opening side portion 52aHa maintains the same groove width as the opening width W52aH of the tread contact surface 2 in the tire radial direction inner side (groove depth direction), and the groove bottom side portion 52aHb is continuous in the groove depth direction with a groove width wider than the opening width W52 aH.

In the hidden groove portion 52aH of the 1 st branch groove 52a, the groove width of the opening side portion 52aHa is constant, while the groove width of the groove bottom side portion 52aHb of the hidden groove portion 52aH gradually increases from the tread contact surface 2 side toward the groove bottom 52aHB side in a section to the vicinity of the middle of the groove bottom side portion 52aHb, and thereafter gradually decreases or is maintained constant in a section from the vicinity of the middle of the groove bottom side portion 52aHb to the groove bottom 52 aHB. That is, the groove bottom side portion 52aHb in this example has a deformed hexagonal shape in a cross-sectional view of a plane orthogonal to the extending direction of the 1 st branch groove 52 a.

However, in the inner resonator of the present invention, the groove bottom side portion 52aHb of the hidden groove portion 52aH provided in the 1 st branch groove 52a may be formed in a shape (for example, a circular shape, an elliptical shape, or a rhombic shape) in which the groove width gradually increases and gradually decreases from the tread contact surface 2 side toward the groove bottom 52aHB side in the cross-sectional view, a shape (for example, a quadrangular shape) in which the groove width is constant from the tread contact surface 2 side toward the groove bottom 52aHB side, a shape (for example, a triangular shape or a semicircular shape) in which the groove width gradually increases from the tread surface 2 side toward the groove bottom 52aHB side at all times, or the like.

In the internal resonator of the present invention, the hidden groove portion 52aH provided in the 1 st branch groove 52a may not have the open side portion 52 aHa. That is, the hidden groove portion 52aH may have the following structure: the groove width gradually increases from the tread surface 2 side toward the groove bottom 52aHB side, so that the opening width W52aH at the tread surface 2 is smaller than the groove width W52aHB at the groove bottom 52aHB side.

Further, fig. 6 is a sectional view taken along line d-d of fig. 2. Here, the 1 st sub-groove 51 and the 1 st branch groove 52a are shown in a developed manner in cross section along the plane of the opening center. In the 1 st sub-groove 51 of the inner resonator 5, the groove depth gradually decreases from the 1 st sub-groove 52b side (right side in the drawing) toward the 1 st sub-groove 52a side (left side in the drawing), but a groove deepest portion 51Dp where the groove depth of the 1 st sub-groove 51 becomes the largest is provided at least in the central portion in the extending direction of the 1 st sub-groove 51.

Further, the groove depth of the 1 st sub groove 51 becomes smallest at a portion where the 1 st sub groove 51 is adjacent to the 1 st branch groove 52 a. That is, in the 1 st sub groove 51, in an expanded view of a cross section along the extending direction of the 1 st sub groove 51, a groove depth is smallest between a groove deepest portion 51Dp and the 1 st branch groove 51a connected to the 1 st sub groove 51, and the groove deepest portion 51Dp is disposed at least in the extending direction center portion of the 1 st sub groove 51. According to this structure, uneven wear of the tread can be more reliably suppressed while air columnar resonance noise is more effectively reduced.

In the inner resonator 5, the 1 st sub-groove 51 is locally deep in the deepest groove portion 51 Dp. However, in the tire of the present invention, the groove depth of the 1 st sub-groove may be gradually increased from the end portion on one side and the end portion on the other side in the tire circumferential direction of the 1 st sub-groove toward the center portion in the extending direction of the 1 st sub-groove. In this case, a portion having a groove depth larger than twice the average depth of the 1 st sub-groove 51 is defined as the groove deepest portion 51 Dp.

Further, this tire 1 includes an outer resonator 6 (in the illustrated example, a helmholtz-type resonator) in an outer land portion (in the present embodiment, the outer intermediate land portion 42b) located in a vehicle-mounted outer half HB with respect to a tire equatorial plane C L among the plurality of land portions 4, the outer resonator 6 includes a2 nd sub-groove 61 terminating in the outer intermediate land portion 42b and a2 nd sub-groove 62 communicating the 2 nd sub-groove 61 with the circumferential main groove 3 (in the present embodiment, the 2 nd sub-groove 61 communicates with the circumferential main groove 32b on the vehicle-mounted outer side and the 2 nd sub-groove 61 communicates with the circumferential main groove 31b on the tire equatorial plane C L side).

In the outer resonator 6, the 2 nd branch groove 62a is provided adjacent to the tire circumferential direction center portion of the 2 nd sub-groove 61, and the 2 nd branch groove 62b is provided adjacent to the tire circumferential direction side end portion (upper side in the drawing sheet in fig. 1) of the 2 nd sub-groove 61, that is, in this example, one end of the 2 nd branch groove 62a opens to the outer circumferential direction main groove 32b on the tread ground edge TE side, and the other end of the 2 nd branch groove 62a opens to the tire circumferential direction center portion of the 2 nd sub-groove 61, and similarly, one end of the 2 nd branch groove 62b opens to the outer circumferential direction main groove 31b on the tire equatorial plane C L side, and the other end of the 2 nd branch groove 62b opens to the tire circumferential direction side end portion of the 2 nd sub-groove 61.

In this way, in the outer resonator 6, the 2 nd sub-groove 61 communicates with the two outer circumferential main grooves 31b, 32b by including the two 2 nd branch grooves 62a, 62b, but in the tire of the present invention, the outer resonator may be configured to include only one 2 nd branch groove, or configured to communicate with one outer circumferential main groove although two 2 nd branch grooves are included. In the tire of the present invention, the outer resonators may include three, four, or four or more of the 2 nd branch grooves.

In the tire of the present invention, both the 2 nd sub grooves 62a and 62b may be provided adjacent to the tire circumferential direction end portions of the 2 nd sub groove 61, and both the 2 nd sub grooves 62a and 62b may be provided adjacent to the tire circumferential direction center portion of the 2 nd sub groove 61.

In the outer resonator 6, the 2 nd sub-groove 61 has a larger groove volume than either of the two 2 nd sub-grooves 62a and 62b connected to the 2 nd sub-groove 61. The opening area of the 2 nd sub-groove 61 that opens in the tread contact surface 2 is larger than the opening area of either of the two 2 nd sub-grooves 62a and 62b that connect to the 2 nd sub-groove 61 that opens in the tread contact surface 2.

In addition, in the outer resonator 6, the hidden groove portion having the opening width smaller than the groove width of the groove bottom in the tread contact surface 2 is not provided in any of the 2 nd branch grooves 62a and 62b, but in the tire of the present invention, the hidden groove portion similar to the inner resonator 5 may be provided in at least one of the 2 nd branch grooves 62a and 62 b.

Here, in this tire 1, the tire circumferential direction length L6 of the outer resonator 6 at the tread contact surface 2 is smaller than the tire circumferential direction length L5 of the inner resonator 5.

In the tire 1, the inner resonators 5 are arranged at the inner intermediate land portion 42a with a constant interval over the entire range in the tire circumferential direction, and the outer resonators 6 are arranged at the outer intermediate land portion 42b with a constant interval over the entire range in the tire circumferential direction.

Here, in this tire 1, the volume of the 2 nd sub-groove 61 of the outer resonator 6 is smaller than the volume of the 1 st sub-groove 51 of the inner resonator 5, and the number of the outer resonators 6 arranged over the entire range in the tire circumferential direction is larger than the number of the inner resonators 5 arranged over the entire range in the tire circumferential direction.

That is, in this tire 1, the arrangement pitch of the outer resonators 6 in the tire circumferential direction is smaller than the arrangement pitch of the inner resonators 5 in the tire circumferential direction. In addition, when the inner resonator 5 and the outer resonator 6 do not have a constant pitch in the tire circumferential direction but are arranged with a variable interval in the tire circumferential direction, the average pitch over the entire range in the tire circumferential direction is set as the arrangement pitch of the inner resonator 5 and the outer resonator 6.

In the tire 1, the tire circumferential positions of the inner resonators 5 adjacent to each other in the tire circumferential direction do not overlap each other, but the tire circumferential positions of the outer resonators 6 adjacent to each other in the tire circumferential direction overlap each other.

In the tire 1, the hidden groove portion 52aH of the 1 st branch groove 52a of the inner resonator 5 and the 2 nd sub-groove 61 of the outer resonator 6 overlap each other in the tire width direction. More specifically, in the illustrated example, the entire area of the extension area in the tire circumferential direction of the hidden groove portion 52aH of the 1 st branch groove 52a of the inner resonator 5 overlaps with the extension area in the tire circumferential direction of the 1 st sub-groove 62 of the outer resonator 6 in the tire width direction. In particular, in the tire 1, the maximum width positions of the hidden groove portion 52aH of the 1 st branch groove 52a of the inner resonator 5 and the 2 nd sub-groove 61 of the outer resonator 6 overlap in the tire circumferential direction.

Next, the operation and effect of the tire 1 of the present embodiment will be described.

In this tire 1, as described above, the inner resonator 5 is provided in the inner land portion (in the present embodiment, the inner intermediate land portion 42a) of the plurality of land portions 4 provided in the tread contact surface 2, which is positioned in the vehicle-mounted inner half HA with respect to the tire equatorial plane C L, and the inner resonator 5 includes the 1 st sub-groove 51 terminating in the inner intermediate land portion 42a and the 1 st sub-groove 52 (in the present embodiment, the 1 st sub-grooves 52a, 52b) communicating the 1 st sub-groove 51 with the circumferential main groove 3 (in the present embodiment, the inner circumferential main grooves 31a, 32 a).

In the tire 1, the hidden groove portion 52aH having an opening width smaller than the groove width of the groove bottom in the tread contact surface 2 is provided in the 1 st sub-groove 52 (the 1 st sub-groove 52a in the present embodiment) adjacent to the 1 st sub-groove 51. In the hidden groove portion 52aH, since the opening width W52aH at the tread contact surface 2 is smaller than the groove width W52aHB of the groove bottom 52aHB, an excessive decrease in the stiffness of the land portion due to the provision of the inner resonator 5 at the tread contact surface 2 can be suppressed, whereby uneven wear of the tread can be suppressed.

Further, in the tire 1, since the opening side portion 52aHa maintaining the same groove width as the opening width W52aH in the tread contact surface 2 in the tire radial direction inner side (groove depth direction) is provided in the hidden groove portion 52aH, uneven wear of the tread around the inner resonator 5 can be suppressed more reliably.

In addition, in the tire 1, the outer resonator 6 is provided in the outer land portion (in the present embodiment, the outer intermediate land portion 42b) of the plurality of land portions 4 located in the vehicle-mounted outer half HB with respect to the tire equatorial plane C L, and the outer resonator 6 includes the 2 nd sub-groove 61 that terminates within the outer land portion 42b, and the 2 nd sub-groove 62 (in the present embodiment, the 2 nd sub-groove 62a, 62b) that communicates the 2 nd sub-groove 61 with the circumferential main groove 3 (in the present embodiment, the outer circumferential main grooves 31b, 32b), so that air column resonance noise generated in the outer circumferential main grooves 31b, 32b can be reduced by the outer resonator 6, and therefore, air column resonance noise generated in the tire can be further reduced as compared with a case where only the inner resonator 5 is provided in the tread 2.

In the tire 1, the tire circumferential direction length L6 of the outer resonator 6 in the tread contact surface 2 is smaller than the tire circumferential direction length L5 of the inner resonator 5, and generally, the tread contact length is longer in the vehicle-mounted inner half HA than in the vehicle-mounted outer half HB, and therefore, if the tire circumferential direction length L6 of the outer resonator 6 is made smaller than the tire circumferential direction length L5 of the inner resonator 5, the number of the outer resonators 6 included in the contact surface increases, and therefore, the air column resonance sound can be further reduced.

In the tire 1, the volume of the 2 nd sub-groove 61 of the outer resonator 6 is smaller than the volume of the 1 st sub-groove 51 of the inner resonator 5, and the number of the outer resonators 6 arranged in the entire tire circumferential direction is larger than the number of the inner resonators 5 arranged in the entire tire circumferential direction. In this way, if the number of outer resonators 6 arranged over the entire range in the tire circumferential direction is made larger than the number of inner resonators 5 arranged over the entire range in the tire circumferential direction, the number of outer resonators 6 included in the ground surface increases, which is advantageous in further reducing air column resonance noise. However, as the number of the outer resonators 6 increases, the rigidity of the outer intermediate land portion 42b provided with the outer resonators 6 decreases. Therefore, if the volume of the 2 nd sub-groove 61 of the outer resonator 6 is made smaller than the volume of the 1 st sub-groove 51 of the inner resonator 5, the rigidity distribution of the tread can be made uniform, and uneven wear of the tread can be suppressed.

Further, in the tire 1, at least two circumferential main grooves 3 are provided, and the groove width of the circumferential main groove on the innermost side in the vehicle mounting (the inner circumferential groove 32a in the present embodiment) is the largest among the circumferential main grooves 3. In this case, since the water is efficiently drained by the inner circumferential main groove 32a, which is the innermost side in the vehicle mounting and has the largest groove width, the drainage performance can be particularly improved during the straight traveling.

In addition, generally, when the circumferential main groove 3 having a large groove width and in which the air column resonance sound is increased is disposed at the innermost side of the vehicle, it is possible to minimize the noise emitted to the outside.

In the tire 1, the hidden groove portion 52aH of the 1 st branch groove 52a of the inner resonator 5 and the 2 nd sub-groove 61 of the outer resonator 6 overlap each other in the tire width direction. In this case, since the hidden groove portion 52aH in which the rigidity of the land portion can be maintained high and the 2 nd sub-groove 61 in which the rigidity of the land portion is likely to decrease overlap in the tire width direction, the rigidity distribution of the tread can be further uniformized, and uneven wear of the tread can be more reliably suppressed.

In particular, in the tire 1, since the hidden groove portion 52aH of the 1 st branch groove 52a of the inner resonator 5 and the maximum width position of the 2 nd sub-groove 61 of the outer resonator 6 overlap in the tire circumferential direction, it is particularly advantageous to efficiently uniformize the rigidity distribution in the tire width direction.

Further, in the tire 1, the opening width at the tread contact surface 2 of the 1 st sub-groove 51 and the 2 nd sub-groove 61 is gradually increased from one end in the tire circumferential direction of the 1 st sub-groove 51 and the 2 nd sub-groove 61 toward the maximum width position of the 1 st sub-groove 51 and the 2 nd sub-groove 61, and is gradually decreased from the maximum width position toward the other end in the tire circumferential direction of the 1 st sub-groove 51 and the 2 nd sub-groove 61. In this case, when the tire rolls under load, the groove widths of the 1 st sub-groove 51 and the 2 nd sub-groove 61 in the center portion in the tire circumferential direction are likely to change, and water entering the 1 st sub-groove 51 and the 2 nd sub-groove 61 can be efficiently discharged, so that the drainage can be further improved.

In the tire 1, the groove depth of the 1 st branch groove 52a of the inner resonator 5 is largest at the hidden groove portion 52 aH. Therefore, both the quietness (the effect of reducing air columnar resonance noise) and the uneven wear resistance can be achieved.

In the tire 1, the groove deepest portion 51Dp, at which the groove depth D51 of the 1 st sub-groove 51 becomes the largest, is provided at least in the extending direction center portion of the 1 st sub-groove 51 of the inner resonator 5. If the groove deepest portion 51Dp is provided, the groove volume of the sub-groove 51 can be easily secured, and therefore the drainage can be further improved.

Further, if the groove deepest portion 51Dp is configured such that the depth of the 1 st sub-groove 51 becomes locally deeper in the groove deepest portion 51Dp as in the tire 1 of the present embodiment, the rigidity of the land portion (the inner intermediate land portion 42a in the present embodiment) provided with the inner resonator 5 is easily maintained, and uneven wear of the tread can be more reliably suppressed, as compared with the case where the groove deepest portion 51Dp is configured such that the depth of the 1 st sub-groove 51 becomes gradually deeper.

Here, in the vehicle-mounted inner half HA, the ground contact width of the inner shoulder land portion 43a (the distance in the tire width direction between the ground contact ends of the ground contact surfaces when the tire is mounted on the application rim, the predetermined internal pressure is applied, and the maximum load is applied) is preferably smaller than the ground contact width of the inner intermediate land portion 42 a.

Further, it is preferable that, in the vehicle-mounted outer side half HB, the ground contact width of the outer shoulder land portion 43b is smaller than the ground contact width of the outer intermediate land portion 42 b.

In the case where the center land portion 41 is formed as in the embodiment shown in fig. 1, it is preferable that the ground contact width of the center land portion 41 among the plurality of land portions is the smallest.

In the present invention, it is preferable that the inner circumferential main groove 32a, which is located on the outermost side in the tire width direction, of the plurality of circumferential main grooves has the largest groove width. This is because the ground contact length on the vehicle-mounted inner side is likely to be elongated during traveling, and the contribution to the water-level performance is large, so that the water-level performance can be effectively improved.

In the present invention, the edge length per unit area in the tire width direction is preferably such that the edge length per unit area in the tire width direction of the outer shoulder land portion 43b is greater than the edge length per unit area in the tire width direction of the inner shoulder land portion 43 a.

Further, the edge length per unit area in the tire width direction is preferably such that the edge length per unit area in the tire width direction of the outer intermediate land portion 42b is larger than the edge length per unit area in the tire width direction of the inner intermediate land portion 42 a.

Further, the edge length per unit area in the tire circumferential direction is preferably such that the edge length per unit area in the tire circumferential direction of the inner shoulder land portion 43a is larger than the edge length per unit area in the tire circumferential direction of the outer shoulder land portion 43 b.

This is because the grounding length can be optimized, the performance of the resonator can be more effectively exhibited, and the quietness can be further improved.