JP7518719B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

In pneumatic tires, it is desirable to improve drainage. For example, in Patent Document 1, pin-shaped sipes are provided in part of the extension region of the widthwise sipes that extend in the tread width direction, and water between the tire and the road surface can enter these pin-shaped sipes, improving drainage. In addition, by providing pin-shaped sipes, the edge components in the width direction are reduced compared to when drainage is improved by widthwise sipes, so ride comfort can be improved.

JP 2017-193222 A

However, the technology described in Patent Document 1 could reduce the rigidity of the land area, resulting in a decrease in maneuverability such as steering stability. There was also a concern that stones on the road surface could get caught near the pin-shaped sipes.

The present invention aims to provide a pneumatic tire that ensures drainage and ride comfort without significantly compromising other driving performance and that can suppress stone entrapment.

The gist and configuration of the present invention are as follows.
(1) The tire has one or more circumferential main grooves extending in the circumferential direction of the tread on the tread surface of the tread portion,
A widthwise outermost land portion on one side in the tread width direction defined by a tread edge and the circumferential main groove has a plurality of widthwise sipes extending in the tread width direction and a plurality of pin-shaped sipes,
The pin-shaped sipes are not connected to the widthwise sipes and are arranged on the extension lines of the widthwise sipes,
The pin-shaped sipes are arranged in only one row at intervals in the tread circumferential direction,
The pin-shaped sipe is disposed on the outer side in the tire width direction than a tread width direction midpoint of the outermost land portion in the width direction,
A pneumatic tire, wherein the widthwise outermost land portion does not have a circumferential sipe extending in the tread circumferential direction.

Here, "tread surface" refers to the entire circumferential area of the tread that comes into contact with the road surface when a pneumatic tire is mounted on an applicable rim, inflated to the specified internal pressure, and subjected to the maximum load.
Moreover, the term "tread edge" refers to both ends of the contact surface in the tread width direction.
In addition, a "circumferential main groove" refers to a groove that extends in the circumferential direction of the tread and has a groove width (opening width) of 2 mm or more when the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and no load is applied. A "circumferential sipe" refers to a groove that extends in the circumferential direction of the tread and has a groove width (opening width) of less than 2 mm when the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and no load is applied. When a "circumferential main groove" or a "circumferential sipe" is referred to as "extending in the circumferential direction of the tread," this includes not only the case where the groove extends in the circumferential direction of the tread (inclination angle of 0° relative to the circumferential direction of the tread), but also the case where the groove extends at an inclination angle of 5° or less relative to the circumferential direction of the tread.
In addition, the "widthwise groove" described below refers to a groove that extends in the tread width direction and has a groove width (opening width) of 2 mm or more when the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and no load is applied. The "widthwise sipe" refers to a groove that extends in the tread width direction and has a groove width (opening width) of less than 2 mm when the pneumatic tire is mounted on an applicable rim, inflated to a specified internal pressure, and no load is applied.

The above-mentioned "applicable rim" refers to the standard rim for the applicable size that is described or will be described in the future in the industrial standards in effect in the region where the tire is manufactured and used, such as the JATMA YEAR BOOK of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the STANDARDS MANUAL of the European Tire and Rim Technical Organization (ETRTO) in Europe, and the YEAR BOOK of the Tire and Rim Association, Inc. (TRA) in the United States. The term "applicable rim" refers to a rim having a width corresponding to the bead width of the tire (i.e., the above "applicable rim" includes not only current sizes but also sizes that may be included in the above industry standard in the future. Examples of "sizes to be described in the future" include sizes described as "FUTURE DEVELOPMENTS" in the 2013 edition of the ETRTO STANDARDS MANUAL). However, in the case of sizes not described in the above industry standard, the term refers to a rim with a width corresponding to the bead width of the tire.
In addition, the "prescribed internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in the applicable size and ply rating, as described in the above-mentioned JATMA YEAR BOOK, etc., and in the case of a size not described in the above-mentioned industrial standard, the "prescribed internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Furthermore, the "maximum applied load" refers to the load corresponding to the above-mentioned maximum load capacity. Note that the air referred to here can be replaced with an inert gas such as nitrogen gas or the like.

(2) A pneumatic tire as described in (1) above, in which the outermost land portion in the width direction on one side of the tread width direction is the inner land portion when mounted on a vehicle.

(3) A pneumatic tire as described in (1) or (2) above, in which the pin-shaped sipes are arranged only on the outermost land portion in the width direction on one side of the tread width direction.

(4) The tire has two or more circumferential main grooves,
A first resonator is disposed in a first central land portion that is partitioned between the two circumferential main grooves and is adjacent to the tread widthwise inner side of the widthwise outermost land portion on one side of the tread width direction, the first resonator having a first air chamber portion that terminates in the first central land portion and a first narrowed neck portion that communicates between the circumferential main groove on the tire widthwise outer side of the first central land portion and the first air chamber portion,
The first air chamber has a groove width that gradually increases from one side to the other side in the tread circumferential direction in a plan view,
The pneumatic tire according to any one of (1) to (3) above, wherein the first narrowed neck portion is connected to an end portion of the first air chamber portion on one side in the tread circumferential direction.

(5) A pneumatic tire as described in (4) above, in which the first narrowed neck portion has an expanded diameter portion on the groove bottom side, the groove width of which is larger than the groove width at the opening to the tread surface.

(6) Having two or more of the circumferential main grooves,
The pneumatic tire according to any one of (1) to (5), wherein the groove width of the circumferential main groove located on the outermost side in the width direction on the other side in the tread width direction is larger than the groove width of any of the other circumferential main grooves.

(7) A pneumatic tire according to any one of (4) to (6) above, in which the first air chamber extends along the tread circumferential direction.

(8) Having two or more of the circumferential main grooves,
a second central land portion that is defined between the two circumferential main grooves and adjacent to an outermost land portion in the width direction on the other side of the tread width direction defined by the tread edge and the circumferential main grooves, and a plurality of second resonators are arranged in the second central land portion, the second resonators having a second air chamber portion that terminates in the second central land portion and a second narrowed neck portion that communicates between the circumferential main groove and the second air chamber portion;
The second air chamber has a central portion on a central side in the tread width direction and two raised side portions adjacent to groove walls on both sides in the tread width direction,
the central portion has a first raised portion that is raised on a circumferential central side of the tread in comparison with an end side in the tread width direction,
The pneumatic tire according to (7) above, wherein each of the two side portions has a second raised portion on a circumferential center side of the tread that is raised higher than the end sides in the tread width direction.

(9) A pneumatic tire as described in (8) above, in which the second narrowed neck portion has an expanded diameter portion on the groove bottom side, the groove width of which is larger than the groove width at the opening to the tread surface.

(10) Having two or more of the circumferential main grooves,
The pneumatic tire according to any one of (1) to (9), wherein a widthwise outermost land portion on the other side of the tread width direction defined by a tread end and the circumferential main groove does not have a circumferential sipe extending in the tread circumferential direction.

(11) Having two or more of the circumferential main grooves,
A pneumatic tire according to any one of (1) to (10) above, wherein a second central land portion that is defined between the two circumferential main grooves and adjacent to the widthwise outermost land portion on the other side of the tread width direction defined by the tread end and the circumferential main grooves does not have a circumferential sipe extending in the tread circumferential direction.

(12) The tire has three or more circumferential main grooves,
A first resonator is disposed in a first central land portion that is partitioned between the two circumferential main grooves and is adjacent to the tread widthwise inner side of the widthwise outermost land portion on one side of the tread width direction, the first resonator having a first air chamber portion that terminates in the first central land portion and a first narrowed neck portion that communicates between the circumferential main groove on the tire widthwise outer side of the first central land portion and the first air chamber portion,
A second central land portion is partitioned between the two circumferential main grooves and is adjacent to the tread widthwise inner side of the widthwise outermost land portion on the other side of the tread width direction. A second resonator is disposed in the second central land portion, the second resonator having a second air chamber portion terminating in the second central land portion and a second narrowed neck portion communicating between the circumferential main groove on the tire widthwise outer side of the second central land portion and the second air chamber portion,
The pneumatic tire according to any one of (1) to (11) above, wherein the plurality of first resonators and the plurality of second resonators are arranged such that, at any position in the tread circumferential direction, when viewed in the tread width direction, either or both of the first air chamber portion and the second air chamber portion are present.

The present invention provides a pneumatic tire that ensures drainage and ride comfort without significantly compromising other driving performance and that can suppress stone entrapment.

1 is a development view of a tread showing a contact surface of a tread portion of a tire according to one embodiment of the present invention. FIG. 4 is an enlarged view of the second resonator and the circumferential main groove. FIG. 2 is a cross-sectional view of the second constriction neck portion. FIG. 4 is an enlarged view of the second air chamber portion. FIG. 4 is a cross-sectional view of the second air chamber portion. 1A and 1B are plan and cross-sectional views of a pin-shaped sipe.

The following is a detailed description of an embodiment of the present invention, with reference to the drawings. When dimensions of components are described below, unless otherwise specified, they refer to the dimensions when the pneumatic tire is mounted on the applicable rim, inflated to the specified internal pressure, and unloaded.

The internal structure of the pneumatic tire of the present invention (hereinafter also simply referred to as "tire") can be the same as that of the conventional tire, so a description thereof will be omitted. As an example, the tire can be configured with a carcass that spans a pair of bead portions in a toroidal shape, and a belt and tread portion that are disposed radially outward of the carcass.

Figure 1 is a tread development showing the tread surface of a tire according to one embodiment of the present invention. As shown in Figure 1, this tire has one or more (three in the illustrated example) circumferential main grooves 2 (2a, 2b, 2c) extending in the tread circumferential direction on the tread surface 1 of the tread.

Land portions 3 (3a, 3b, 3c, 3d) (four in the illustrated example) are defined between the tread end TE and the circumferential main groove 2 or between the circumferential main grooves 2. That is, the tread end TE and the circumferential main groove 2a on one side in the tread width direction define the widthwise outermost land portion 3a on one side in the tread width direction, and the tread end TE and the circumferential main groove 2c on the other side in the tread width direction define the widthwise outermost land portion 3d on the other side in the tread width direction. Furthermore, a first central land portion 3b is defined between the circumferential main grooves 2a and 2b, adjacent to the widthwise inner side of the widthwise outermost land portion 3a on one side in the tread width direction, and a second central land portion 3c is defined between the circumferential main grooves 2b and 2c, adjacent to the widthwise inner side of the widthwise outermost land portion 3d on the other side in the tread width direction.
In the illustrated example, the second central land portion 3c is located on the tire equatorial plane CL, the circumferential main grooves 2a and 2b are located in the tread half on one side in the tread width direction, and the circumferential main groove 2c is located in the tread half on the other side in the tread width direction. However, the present invention is not limited to this case, and for example, the circumferential main groove may be located on the tire equatorial plane CL.
In the illustrated example, all the land portions 3 are rib-like land portions (land portions that are not completely divided in the tread circumferential direction by widthwise grooves), but any of the land portions 3 may be block-like. Note that in this specification, even if a land portion is completely divided in the tread circumferential direction by a widthwise sipe, it is included in the rib-like land portion.
The tire in the illustrated example is configured so that one side in the tread width direction can be the inner side when mounted on a vehicle, and the other side in the tread width direction can be the outer side when mounted on a vehicle.
The number of the circumferential main grooves 2 is not limited to three and may be, for example, four. Accordingly, the number of the land portions 3 is also not limited to four and may be, for example, five.

The groove width (opening width) of the circumferential main groove 2 is not particularly limited, but may be 10 to 14 mm, and the groove depth (maximum depth) of the circumferential main groove 2 is not particularly limited, but may be 5 to 9 mm. In addition, it is preferable that the groove width of the circumferential main groove located on the outermost side in the width direction on the other side of the tread width direction (circumferential main groove 3c in the illustrated example) is larger than the groove width of any of the other circumferential main grooves (circumferential main grooves 3a, 3b in the illustrated example). In addition, in the illustrated example, all of the circumferential main grooves 2 extend straight in the tread circumferential direction, but they may extend in a zigzag, curved, or bent shape in the tread circumferential direction.

The size relationship of the widths of the land portions 3 in the tread width direction is not particularly limited, but for example, as shown in the figure, it is preferable to make the width of the first central land portion 3b in the tread width direction smaller than the width of the second central land portion 3c in the tread width direction. When one side in the tread width direction is the inner side when mounted on the vehicle, it is possible to effectively achieve both steering stability and ride comfort by relatively increasing the rigidity of the outer side when mounted on the vehicle (which contributes more to steering stability) and relatively decreasing the rigidity of the inner side when mounted on the vehicle (which contributes more to ride comfort).

As shown in FIG. 1, the land portion 3a has multiple widthwise sipes 4 extending in the tread width direction, and multiple pin-shaped sipes 5. On the other hand, the land portion 3a does not have circumferential sipes extending in the tread circumferential direction. Furthermore, the land portion 3a does not have widthwise grooves.

The land portion 3a has two types of widthwise sipes 4: a first widthwise sipe 4a that connects from the tread end TE to the circumferential main groove 2a, and a second widthwise sipe 4b that extends from the circumferential main groove 2a to the outside in the tread width direction and terminates within the land portion 3a (near the widthwise center of the land portion 3a in the illustrated example). The first widthwise sipe 4a and the second widthwise sipe 4b are alternately arranged in the tread circumferential direction. The first and second widthwise sipes 4a, 4b are not particularly limited, but can extend in the tread width direction (incline angle 0°) or extend at an inclination angle of 45° or less with respect to the tread width direction. In the illustrated example, the first and second widthwise sipes 4a, 4b do not have a bent portion, but can also have a bent portion. The sipe width (opening width) of the widthwise sipes 4a and 4b is not particularly limited, but can be 0.5 to 2 mm, and the sipe depth (maximum depth) of the widthwise sipes 4a and 4b is not particularly limited, but can be 3 to 9 mm. Note that the first widthwise sipe 4a does not necessarily have to be present.

4 is a plan view and a cross-sectional view of a pin-shaped sipe. As shown in FIG. 4, the pin-shaped sipe 5 is a small-diameter hole with a circular opening in a plan view. The diameter of the hole (maximum diameter of the opening) is large enough that the wall surfaces do not come into contact with each other when the tire is mounted on the applicable rim, filled with the specified internal pressure, and subjected to the maximum load. Specifically, although not particularly limited, the diameter of the hole can be 2 to 6 mm. By making the diameter of the hole 2 mm or more, the effect of improving drainage can be more effectively exhibited, while on the other hand, by making the diameter of the hole 6 mm or less, the rigidity of the land portion can be prevented from decreasing as much as possible. The depth of the hole can be, although not particularly limited, 3 to 9 mm. By making the depth of the hole 3 mm or more, the effect of improving drainage can be more effectively exhibited, while on the other hand, by making the depth of the hole 9 mm or less, the rigidity of the land portion can be prevented from decreasing as much as possible. It is preferable that the opening of the pin-shaped sipe 5 is circular in a plan view in order to suppress the occurrence of cracks in the sipe 5, but it can also be elliptical or polygonal. The diameter of the hole can be constant in the direction of the hole depth, or can vary (e.g., gradually decrease or increase) from the opening side toward the sipe bottom side. For example, an enlarged diameter portion (preferably having a maximum diameter 1.5 to 3 times the diameter of the sipe opening) can be provided at the position of the sipe bottom (preferably 80% to 100% of the sipe depth). The sipe bottom of the pin-shaped sipe 5 can also be rounded to suppress crack generation at the sipe bottom. In the example shown in Figure 4, the diameter is constant from the opening to about half the groove depth, and then the diameter gradually decreases toward the sipe bottom.

The pin-shaped sipes 5 are not connected to the widthwise sipes 4b, but are arranged on the extension line of the widthwise sipes 4b. The "extension line" is a straight line connecting the outer end of the widthwise sipe in the tread width direction and a point 1 mm inward from the outer end along the periphery of the widthwise sipe, and "arranged on the extension line" includes cases where the pin-shaped sipe part intersects with the straight line, or the shortest distance between the pin-shaped sipe part and the straight line is 0.5 m or less. Furthermore, the pin-shaped sipes 5 consist of only one row arranged at intervals in the tread circumferential direction (in the illustrated example, multiple pin-shaped sipes 5 are arranged at the same position in the tread width direction at approximately equal intervals in the tread circumferential direction). The pin-shaped sipes 5 are arranged on the outer side in the tire width direction than the tread width direction midpoint of the outermost land portion 3a in the width direction. The pin-shaped sipes 5 are arranged only on the outermost land portion 3a on one side of the tread width direction, and are not arranged on the other land portions 3b, 3c, and 3d.

Next, in the first central land portion 3b, a plurality of first resonators 6 are arranged in the tread circumferential direction. The first resonators 6 have a first air chamber portion 6a that terminates within the first central land portion 3b and a first narrowed neck portion 6b that connects the circumferential main groove 2a on the outer side of the first central land portion 3b in the tire width direction to the first air chamber portion 6a. In this example, the first resonators 6 are Helmholtz-type resonators.

In this example, the first air chamber 6a extends along the tread circumferential direction from one side in the tread circumferential direction (upper side in the figure) to the other side in the tread circumferential direction (lower side in the figure). More specifically, the first air chamber 6a has a shape in which the length in the tread circumferential direction projected in the tread width direction is longer than the length in the tread width direction projected in the tread circumferential direction, and for example, the ratio of the tread circumferential length/the tread width direction length can be 2 to 4. The groove volume of the first air chamber 6a is larger than the groove volume of the first narrowed neck portion 6b. The specific volume can be appropriately adjusted according to the frequency band of the sound that the first resonator 6 is intended to reduce. In this example, the first air chamber 6a has a substantially triangular shape in plan view, with the groove width gradually increasing from one side in the tread circumferential direction to the other side. Note that the shape of the first air chamber 6a is not limited to this shape, and can be various shapes that function as a resonator.

In the illustrated example, the first narrowed neck portion 6b is connected to the circumferential main groove 2a on the tread edge TE side, but it can also be connected to the circumferential main groove 2b on the tire equatorial plane CL side. In this example, the first narrowed neck portion 6b is connected to the end of the first air chamber portion 6a on one side of the tread circumferential direction. Alternatively, the first narrowed neck portion 6b can be connected to the end of the first air chamber portion 6a on the other side of the tread circumferential direction. The groove width (opening width) of the narrowed neck portion 6b is not particularly limited, but is preferably 0.4 to 1.2 mm, for example. If the groove width is 0.4 mm or more, the first narrowed neck portion 6a is not closed when the tire comes into contact with the ground, and the function of the first resonator 6 can be exerted. On the other hand, if the groove width is 1.2 mm or less, the rigidity of the land portion around the first narrowed neck portion 6b can be secured, and uneven wear can be suppressed. For the same reason, it is more preferable that the groove width of the first narrowed neck portion 6 is 0.5 to 0.7 mm. In addition, the first narrowed neck portion 6b has an expanded diameter portion on the groove bottom side where the groove width is larger than the groove width (opening width) at the opening to the tread surface 1. This can improve drainage when wear progresses. On the other hand, the first narrowed neck portion 6b may not have an expanded diameter portion on the groove bottom side. The expanded diameter portion is preferably provided at a position 80% to 100% of the groove depth, and preferably has a maximum diameter 1.5 to 3 times the opening width.

In addition, the first central land portion 3b also has a plurality of third widthwise sipes 7 (spaced apart in the tread circumferential direction) that extend from the circumferential main groove 2b on the tire equatorial plane CL side to the inside in the tread width direction and terminate within the first central land portion 3b. This increases the widthwise edge component, thereby improving driving performance such as traction performance. The third widthwise sipes 7 are not connected to the first resonator 6. The sipe width (opening width) of the third widthwise sipes 7 is not particularly limited, but can be 0.2 to 1 mm, and the sipe depth (maximum depth) of the third widthwise sipes 7 is not particularly limited, but can be 2 to 6 mm. The first central land portion 3b does not have a circumferential sipe extending in the tread circumferential direction. The first central land portion 3b also does not have a widthwise groove.

Next, in the second central land portion 3c, a plurality of second resonators 8 having a second air chamber portion 8a terminating in the second central land portion 3c and a second narrowed neck portion 8b (8c) (two for each second air chamber portion 8b in this example) that communicates between the second air chamber portion 8a and the circumferential main groove 2b (2c) are arranged in the tread circumferential direction. In this example, the second resonator 8 is a Helmholtz-type resonator. In the illustrated example, the second resonator 8 has two types of narrowed neck portions, one narrowed neck portion 8b communicating with the circumferential main groove 2b on the tire equatorial plane CL side, and the other narrowed neck portion 8c communicating with the circumferential main groove 2c on the tread end TE side. As a result, the second resonator 8 can exert a reduction effect on both the sound generated in the circumferential main groove 2b and the sound generated in the circumferential main groove 2c. On the other hand, the narrowed neck portion may be connected to only one of the circumferential main grooves (in this case, for example, one narrowed neck can be provided for one air chamber portion). The second central land portion 3c does not have a circumferential sipe extending in the tread circumferential direction. The second central land portion 3c also does not have a widthwise groove.

FIG. 2A is an enlarged view showing the second resonator and the circumferential main groove in FIG. 1 .
As shown in FIG. 2A, the second air chamber 8a has a central portion 8a1 on the tread width direction center side and two raised side portions 8a2, 8a3 adjacent to the groove walls on both sides in the tread width direction. In the illustrated example, the groove width of the central portion 8a1 gradually increases from the end portion on one side in the tread circumferential direction toward the central portion side in the tread circumferential direction, and gradually decreases from the central portion side in the tread circumferential direction toward the end portion on the other side in the tread circumferential direction. In the illustrated example, the side portion 8a2 on the circumferential main groove 2c side extends in the tread circumferential direction from the end portion on one side in the tread circumferential direction of the central portion 8a1 to the vicinity of the center of the central portion 8a1. The groove width of the side portion 8a2 gradually increases from one side in the tread circumferential direction to the vicinity of the center of the central portion 8a1. In the illustrated example, the side portion 8a3 on the circumferential main groove 2b side extends in the tread circumferential direction from the end of the central portion 8a1 on the other side of the tread circumferential direction to the vicinity of the center of the central portion 8a1. The groove width of the side portion 8a3 gradually increases from the other side of the tread circumferential direction to the vicinity of the center of the central portion 8a1. The side portions 8a2 and 8a3 are arranged so as to have overlapping portions when projected in the tread width direction. The central portion and the side portions will be described in detail later using cross-sectional views.
The second air chamber 8a has a shape in which the length in the tread circumferential direction projected in the tread width direction is longer than the length in the tread width direction projected in the tread circumferential direction, and for example, the ratio of the tread circumferential length/the tread width direction length can be 2 to 4. The groove volume of the second air chamber 8a is larger than the groove volume of the second narrowed neck portions 8b and 8c. The specific volume can be appropriately adjusted depending on the frequency band of the sound that the second resonator 8 is intended to reduce. The shape of the second air chamber 8a is not limited to this shape, and various shapes can be used as long as the function as a resonator is exhibited.

In the illustrated example, the second narrowing neck portion 8b is connected to the end of the second air chamber portion 8a on one side in the tread circumferential direction, and the second narrowing neck portion 8c is connected to the end of the second air chamber portion 8a on the other side in the tread circumferential direction. On the other hand, the second narrowing neck portion 8b can be connected to the end of the second air chamber portion 8a on the other side in the tread circumferential direction, and the second narrowing neck portion 8c can be connected to the end of the second air chamber portion 8a on one side in the tread circumferential direction. Alternatively, both of the second narrowing neck portions 8b and 8c can be connected to the end of the second air chamber portion 8a on one side in the tread circumferential direction, and both of the second narrowing neck portions 8b and 8c can be connected to the end of the second air chamber portion 8a on the other side in the tread circumferential direction. The groove width (opening width) of the narrowed neck portions 8b, 8c is not particularly limited, but is preferably 0.4 to 1.2 mm, for example. If the groove width is 0.4 mm or more, the second narrowed neck portions 8b, 8c are not closed when the tire touches the ground, and the function of the second resonator 8 can be exhibited. On the other hand, if the groove width is 1.2 mm or less, the rigidity of the land portion around the second narrowed neck portions 8b, 8c can be ensured, and uneven wear can be suppressed. For the same reason, the groove width of the second narrowed neck portions 8b, 8c is more preferably 0.5 to 0.7 mm. FIG. 2B is a cross-sectional view of the second narrowed neck portion. As shown in FIG. 2B, the second narrowed neck portions 8b, 8c have an expanded diameter portion on the groove bottom side, in which the groove width is larger than the groove width (opening width) at the opening to the tread surface 1. This can improve the drainage when wear progresses. The second narrowed neck portions 8b, 8c may not have an expanded diameter portion on the groove bottom side. The enlarged diameter portion is preferably located at a position between 80% and 100% of the groove depth, and preferably has a maximum diameter that is 1.5 to 3 times the opening width.

FIG. 3A is an enlarged view showing the second air chamber, and FIG. 3B is a cross-sectional view showing the second air chamber.
As shown in FIG. 3A and FIG. 3B, the central portion 8a1 has a first bottom-up portion that is raised on the tread circumferential center side more than the tread width direction end side. In this example, at the groove width center of the central portion 8a1, a first bottom-up portion that is raised on the tread circumferential center side more than the tread width direction end side (see the b-b cross section). In this example, the bottom-up is smoothly raised by forming a tapered portion. Therefore, as shown in the b-b cross section, the first bottom-up portion is composed of the two tapered portions and the raised groove bottom constant portion sandwiched between them. On the other hand, the groove depth of the groove wall of the central portion 8a1 gradually decreases from the end side of the second air chamber portion 8a toward the central portion (see the c-c cross section, the d-d cross section, and the e-e cross section).
Next, each of the two side portions 8a2, 8a3 has a second bottom-up portion at the tread circumferential center side that is higher than the end side in the tread width direction. In this example, the groove depth gradually decreases from the end side of the second air chamber toward the center side (see the a-a cross section). The height of the bottom-up of the side portions 8a2, 8a3 relative to the center portion 8a1 (starting from the bottom) is approximately constant in the tread circumferential direction (see the ff cross sections, gg cross sections, and h-h cross sections).
The first raised portion and the second raised portion can increase the rigidity of the land portion, and can also suppress stone trapping at the locations where the first raised portion and the second raised portion are formed.

In addition, the second central land portion 3c is also formed with a plurality of fourth widthwise sipes 9 extending from the circumferential main groove 2b to the outside in the tread width direction and terminating within the second central land portion 3c, and a plurality of fifth widthwise sipes 10 extending from the circumferential main groove 2c on the tread end TE side to the inside in the tread width direction and terminating within the second central land portion 3c (spaced apart in the tread circumferential direction). This increases the widthwise edge component and improves driving performance such as traction performance. The fourth and fifth widthwise sipes 9, 10 are not connected to the second resonator 8. The sipe width (opening width) of the fourth and fifth widthwise sipes 9, 10 is not particularly limited, but can be 0.5 to 3 mm, and the sipe depth (maximum depth) of the fourth and fifth widthwise sipes 9, 10 is not particularly limited, but can be 4 to 8 mm. The second central land portion 3c does not have a circumferential sipe extending in the tread circumferential direction. The second central land portion 3c also does not have a widthwise groove.

Next, the land portion 3d has a plurality of widthwise sipes 11 extending in the tread width direction. On the other hand, the land portion 3d does not have a circumferential sipe extending in the tread circumferential direction. Furthermore, the land portion 3d does not have a widthwise groove.
In this example, the land portion 3d has two types of widthwise sipes 11: a sixth widthwise sipe 11a that connects from the tread end TE to the circumferential main groove 2d, and a seventh widthwise sipe 11b that extends from the circumferential main groove 2d to the outside in the tread width direction and terminates within the land portion 3d (beyond the widthwise center of the land portion 3d in the illustrated example). The sixth widthwise sipes 11a and the seventh widthwise sipes 11b are alternately arranged in the tread circumferential direction.
The sixth and seventh widthwise sipes 11a, 11b are not particularly limited, but may extend in the tread width direction (inclination angle 0°) or extend inclined at an inclination angle of 45° or less with respect to the tread width direction. In the illustrated example, the sixth and seventh widthwise sipes 11a, 11b do not have a curved portion, but may have a curved portion. The sipe width (opening width) of the sixth and seventh widthwise sipes 11a, 11b is not particularly limited, but may be 0.2 to 3 mm, and the sipe depth (maximum depth) of the sixth and seventh widthwise sipes 11a, 11b is not particularly limited, but may be 3 to 8 mm.

Next, the layout relationship between the elements between the land portions 3 will be described.
First, the multiple first resonators 6 and the multiple second resonators 8 are arranged so that at any position in the tread circumferential direction, when viewed in the tread width direction, either or both of the first air chamber 6a and the second air chamber 6b are present. That is, when a virtual line is drawn in the tread width direction at any tread circumferential position, the line intersects only with the first air chamber 6a, only with the second air chamber 8a, or with both. This makes it possible to suppress the occurrence of a state in which there are two air chambers in the tread width direction and a state in which there are no air chambers in the tread width direction due to the rotation of the tire, which causes a decrease in ride comfort due to a rigidity step, a decrease in driving performance, uneven wear, etc. In particular, in order to fully exert the sound deadening effect, it is desirable to arrange a sufficient number of resonators in the tread circumferential direction, but this results in many circumferential positions where two resonators are arranged as viewed in the tread width direction. For this reason, the above configuration makes it possible to suppress the occurrence of a decrease in ride comfort, a decrease in driving performance, uneven wear, etc. while achieving sufficient quietness.

In addition, the second widthwise sipe 4b of the land portion 3a and the first narrowed neck portion 6b of the land portion 3b are on an extension line of each other, which makes it possible to efficiently improve drainage.
Moreover, no circumferential sipes are formed in the land portions 3a to 3d, while the first air chamber 6a of the first resonator 6 in the land portion 3b and the second air chamber 8a of the second resonator 8 in the land portion 3c extend along the tread circumferential direction as described above. This makes it possible to ensure the rigidity of the land portions 3a to 3d while also ensuring edge components in the tread circumferential direction, thereby improving the running performance during cornering.
Furthermore, the land portions 3a to 3d do not have widthwise grooves, whereas the land portion 3a has a widthwise sipe 4, the land portion 3b has a widthwise sipe 7, the land portion 3c has widthwise sipes 9 and 10, and the land portion 3d has a widthwise sipe 11. This makes it possible to ensure the rigidity of the land portions 3a to 3d while also ensuring edge components in the tread width direction, thereby improving traction performance and the like.
In this example, the widthwise sipes 4 of the land portion 3a are curved convexly toward one side in the tread circumferential direction, while the widthwise sipes 11 of the land portion 3d are curved convexly toward the other side in the tread circumferential direction.

The effects of the pneumatic tire of the present embodiment will be described below.
First, the pneumatic tire of this embodiment has a widthwise outermost land portion 3a on one side in the tread width direction, which has a plurality of pin-shaped sipes 5. As a result, compared to a case in which widthwise sipes are provided, the edge components in the width direction are reduced to improve ride comfort, while the drainage performance can be improved by the water absorption of the holes in the pin-shaped sipes 5.
In this embodiment, the pin-shaped sipes 5 are arranged in only one row at intervals in the tread circumferential direction, so that the reduction in the area of the land portion is suppressed compared to the case where two or more rows are arranged, and since a region sandwiched between two rows of pin-shaped sipes is not formed, the reduction in the rigidity of the entire land portion is suppressed, and a region where the rigidity is locally reduced can be prevented from being formed. Furthermore, the pin-shaped sipes 5 are not connected to the widthwise sipes 4, and since the pin-shaped sipes 5 are arranged on the tire widthwise outer side of the tread widthwise midpoint of the widthwise outermost land portion 3a, it is not necessary for them to be connected to each other, or for the rigidity to be reduced due to the close distance between them. In addition, since they are not connected to each other, stone trapping can be suppressed. Furthermore, since the pin-shaped sipes 5 are arranged on the extension line of the widthwise sipes 4b, holes are not arranged in the tread circumferential region between the widthwise sipes 4a and the widthwise sipes 4b, so that the rigidity of the land portion in the circumferential region can be ensured. In addition, since the outermost land portion 3a in the width direction does not have a circumferential sipe extending in the tread circumferential direction, the area of the land portion 3a is secured while the land portion 3a is not divided in the tread width direction, and the rigidity of the land portion 3a can be increased. In this way, according to this embodiment, the rigidity of the land portion 3a is secured, and it is possible to prevent a decrease in driving performance such as driving stability, and also to suppress stone trapping.
As described above, the pneumatic tire of the present embodiment can ensure drainage and ride comfort without significantly impairing other driving performance (such as steering stability) and can also suppress stone entrapment.

Here, it is preferable that the outermost land portion in the width direction on one side of the tread width direction is the land portion on the inner side when mounted on the vehicle. By ensuring drainage with pin-shaped sipes in the outermost land portion in the width direction on the inner side when mounted on the vehicle, which has a relatively large contribution to ride comfort, it is possible to efficiently suppress the deterioration of ride comfort due to widthwise edge components compared to when drainage is ensured with widthwise sipes.

It is also preferable that pin-shaped sipes are arranged only in the outermost land portion in the width direction on one side of the tread width direction. This is because it is possible to avoid a decrease in the rigidity of the land portion due to the formation of pin-shaped sipes in other land portions, thereby ensuring driving performance such as steering stability, and also to prevent stone trapping in the pin-shaped sipes in other land portions. In particular, since the outermost land portion in the width direction on the outside when mounted on the vehicle has a relatively large contribution to steering stability, it is efficient to avoid a decrease in rigidity in this land portion. Furthermore, in land portions other than the two outermost land portions in the width direction, resonators are often arranged, for example as in this embodiment, and the area of the land portion tends to decrease, so it is also efficient to avoid a decrease in rigidity in such land portions.

In addition, as in the above embodiment, a first central land portion is partitioned between two circumferential main grooves and adjacent to the tread widthwise inner side of the widthwise outermost land portion on one side of the tread width direction, and a first resonator having a first air chamber portion terminating within the first central land portion and a first narrowed neck portion communicating with the first air chamber portion and the circumferential main groove on the tire widthwise outer side of the first central land portion is preferably arranged, and the groove width of the first air chamber portion gradually increases from one side of the tread circumferential direction to the other side in a plan view, and the first narrowed neck portion is preferably connected to the end of the first air chamber portion on one side of the tread circumferential direction. According to this configuration, the sound generated in the circumferential main groove on the tire widthwise outer side of the first central land portion can be reduced by the resonator. In this case, the first narrowed neck portion communicates with the end of the air chamber on the side with the smaller groove width, thereby minimizing the local decrease in rigidity caused by communication between the circumferential main groove, the first narrowed neck portion, and the first air chamber.

Furthermore, it is also preferable that the first narrowed neck portion has an expanded diameter portion at the bottom of the groove where the groove width is larger than the groove width at the opening to the tread surface. This is because it can improve drainage as wear progresses.

It is also preferable that the tire has two or more circumferential main grooves, and that the groove width of the circumferential main groove located on the outermost side in the width direction on the other side of the tread width is larger than the groove width of any of the other circumferential main grooves.

It is also preferable that the first air chamber portion extends along the tread circumferential direction. This is because the circumferential spacing of the tread increases when the tire rotates while preventing the edge component in the width direction from increasing, further suppressing the deterioration of ride comfort. In particular, when any of the land portions (all land portions in the above embodiment) do not have circumferential sipes, the circumferential edge component tends to decrease, but with the above configuration, the first air chamber portion ensures the circumferential edge component, and it is possible to ensure maneuverability performance such as steering stability during cornering.

In addition, a second central land portion is partitioned between the two circumferential main grooves and adjacent to the outermost land portion on the other side of the tread width direction partitioned by the tread edge and the circumferential main groove. A second resonator having a second air chamber portion terminating within the second central land portion and a second narrowed neck portion connecting the circumferential main groove and the second air chamber portion is arranged in a plurality of positions. The second air chamber portion has a central portion on the tread width direction center side and two raised side portions adjacent to the groove walls on both sides of the tread width direction, respectively. It is preferable that the central portion has a first raised portion on the tread circumferential center side that is raised higher than the tread width direction end side, and each of the two side portions has a second raised portion on the tread circumferential center side that is raised higher than the tread width direction end side. This is because the first raised portion and the second raised portion can increase the rigidity of the land portion and also suppress stone trapping at the locations where the first raised portion and the second raised portion are formed.

It is also preferable that the second narrowed neck portion has an expanded diameter portion at the bottom of the groove where the groove width is larger than the groove width at the opening to the tread surface. This is because it can improve drainage as wear progresses.

Furthermore, it is preferable that the outermost land portion on the other side of the tread width direction, which is defined by the tread edge and the circumferential main groove, does not have a circumferential sipe extending in the tread circumferential direction. This is because it is possible to avoid a decrease in the rigidity of the land portion due to the formation of a circumferential sipe.

In addition, it is preferable that the second central land portion, which is defined between the two circumferential main grooves and adjacent to the outermost land portion on the other side of the tread width direction defined by the tread edge and the circumferential main grooves, does not have a circumferential sipe extending in the tread circumferential direction. This is because it is possible to avoid a decrease in the rigidity of the land portion due to the formation of a circumferential sipe.

Further, as in the above embodiment, a first central land portion is partitioned between two circumferential main grooves and adjacent to the tread widthwise inner side of the widthwise outermost land portion on one side of the tread width direction, and a plurality of first resonators are arranged in the first central land portion, the first resonators having a first air chamber portion terminating within the first central land portion and a first narrowed neck portion communicating between the circumferential main groove on the tire widthwise outer side of the first central land portion and the first air chamber portion,
A second central land portion is partitioned between two circumferential main grooves and is adjacent to the tread widthwise inner side of the widthwise outermost land portion on the other side of the tread width direction. A second resonator is disposed in the second central land portion, the second resonator having a second air chamber portion terminating in the second central land portion and a second narrowed neck portion communicating between the second air chamber portion and the circumferential main groove on the tire widthwise outer side of the second central land portion,
It is preferable that the multiple first resonators and the multiple second resonators are arranged so that either or both of the first air chamber portion and the second air chamber portion are present at any position in the tread circumferential direction when viewed in the tread width direction.
As described above, this is because the rotation of the tire causes a state in which there are two air chambers in the tread width direction and a state in which there is no air chamber in the tread width direction, which can suppress the occurrence of deterioration in ride comfort, deterioration in driving performance, uneven wear, etc. due to rigidity differences (according to the above configuration, there is a state in which there are two air chambers in the tread width direction or a state in which there is one air chamber in the tread width direction). In particular, in order to fully exert the sound deadening effect, it is desirable to arrange a sufficient number of resonators in the tread circumferential direction, but this results in many circumferential positions where two resonators are arranged as viewed in the tread width direction. Therefore, by using the above configuration, it is possible to suppress deterioration in ride comfort, deterioration in driving performance, uneven wear, etc. while achieving sufficient quietness.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. In particular, in the present invention, the land portion other than the outermost land portion in the width direction on one side of the tread width direction is not particularly limited and can be configured in various ways. For example, in this embodiment, the first central land portion and the second central land portion defined by the two circumferential main grooves are both provided with resonators, but any of the land portions defined by the two circumferential main grooves may not have a resonator. In addition, for example, the outermost land portion in the width direction on the other side of the tread width direction may be provided with a width groove communicating with the tread end. In addition, in the above example, the outermost land portion in the width direction on one side of the tread width direction has a width sipe 4a communicating from the tread end TE to the circumferential main groove 2a, but the width sipe 4a may be terminated within the land portion 3a, or the width sipe 4a may not be provided. In addition, various other modifications and changes are possible.
Moreover, the pneumatic tire of the present invention is suitable as a pneumatic tire for passenger cars, and is particularly suitable as a pneumatic tire for minivans.

1: Tread, 2, 2a, 2b, 2c: Circumferential main groove,
3, 3a, 3b, 3c, 3d: land area,
4, 4a, 4b: width direction sipes, 5: pin-shaped sipes,
6: first resonator; 6a: first air chamber portion; 6b: first narrowed neck portion;
7: Width direction sipes,
8: second resonator; 8a: second air chamber portion; 8b: second narrowed neck portion;
9: widthwise sipes, 10: widthwise sipes, 11: widthwise sipes,
CL: tire equatorial plane, TE: tread edge

Claims (11)

The tire has one or more circumferential main grooves extending in the circumferential direction of the tread on the tread surface of the tread portion,
A widthwise outermost land portion on one side in the tread width direction defined by a tread edge and the circumferential main groove has a plurality of widthwise sipes extending in the tread width direction and a plurality of pin-shaped sipes,
The pin-shaped sipes are not connected to the widthwise sipes and are arranged on the extension lines of the widthwise sipes,
The pin-shaped sipes are arranged in only one row at intervals in the tread circumferential direction,
The pin-shaped sipe is disposed on the outer side in the tire width direction than a tread width direction midpoint of the outermost land portion in the width direction,
The widthwise outermost land portion does not have a circumferential sipe extending in the tread circumferential direction,
A pneumatic tire, characterized in that the pin-shaped sipes are arranged only on the widthwise outermost land portion on one side in the tread width direction. The pneumatic tire according to claim 1, wherein the outermost land portion in the width direction on one side of the tread width direction is the inner land portion when mounted on a vehicle. Two or more of the circumferential main grooves are provided,
A first resonator is disposed in a first central land portion that is partitioned between the two circumferential main grooves and is adjacent to the tread widthwise inner side of the widthwise outermost land portion on one side of the tread width direction, the first resonator having a first air chamber portion that terminates in the first central land portion and a first narrowed neck portion that communicates between the circumferential main groove on the tire widthwise outer side of the first central land portion and the first air chamber portion,
The first air chamber has a groove width that gradually increases from one side to the other side in the tread circumferential direction in a plan view,
The pneumatic tire according to claim 1 or 2, wherein the first narrowed neck portion communicates with an end portion of the first air chamber portion on one side in the tread circumferential direction. The pneumatic tire according to claim 3, wherein the first narrowed neck portion has an expanded diameter portion on the groove bottom side, the groove width of which is larger than the groove width at the opening to the tread surface. Two or more of the circumferential main grooves are provided,
The pneumatic tire according to any one of claims 1 to 4, wherein the groove width of the circumferential main groove located on the outermost side in the width direction on the other side in the tread width direction is larger than the groove width of any of the other circumferential main grooves. The pneumatic tire according to claim 3 or 4 , wherein the first air chamber portion extends along a circumferential direction of the tread. Two or more of the circumferential main grooves are provided,
a second central land portion that is defined between the two circumferential main grooves and adjacent to an outermost land portion in the width direction on the other side of the tread width direction defined by the tread edge and the circumferential main grooves, and a plurality of second resonators are arranged in the second central land portion, the second resonators having a second air chamber portion that terminates in the second central land portion and a second narrowed neck portion that communicates between the circumferential main groove and the second air chamber portion;
The second air chamber has a central portion on a central side in the tread width direction and two raised side portions adjacent to groove walls on both sides in the tread width direction,
the central portion has a first raised portion that is raised on a circumferential central side of the tread in comparison with an end side in the tread width direction,
The pneumatic tire according to claim 6 , wherein each of the two side portions has a second raised portion on a circumferential center side of the tread that is raised higher than an end side in the tread width direction. The pneumatic tire according to claim 7, wherein the second narrowed neck portion has an expanded diameter portion on the groove bottom side, the groove width of which is larger than the groove width at the opening to the tread surface. Two or more of the circumferential main grooves are provided,
The pneumatic tire according to any one of claims 1 to 8, wherein a widthwise outermost land portion on the other side in the tread width direction defined by a tread end and the circumferential main groove does not have a circumferential sipe extending in the tread circumferential direction. Two or more of the circumferential main grooves are provided,
10. The pneumatic tire according to claim 1, wherein a second central land portion that is defined between the two circumferential main grooves and adjacent to a widthwise outermost land portion on the other side of the tread width direction defined by the tread end and the circumferential main grooves does not have a circumferential sipe extending in the tread circumferential direction. The circumferential main grooves are three or more.
A first resonator is disposed in a first central land portion that is partitioned between the two circumferential main grooves and is adjacent to the tread widthwise inner side of the widthwise outermost land portion on one side of the tread width direction, the first resonator having a first air chamber portion that terminates in the first central land portion and a first narrowed neck portion that communicates between the circumferential main groove on the tire widthwise outer side of the first central land portion and the first air chamber portion,
A second central land portion is partitioned between the two circumferential main grooves and is adjacent to the tread widthwise inner side of the widthwise outermost land portion on the other side of the tread width direction. A second resonator is disposed in the second central land portion, the second resonator having a second air chamber portion terminating within the second central land portion and a second narrowed neck portion communicating between the circumferential main groove on the tire widthwise outer side of the second central land portion and the second air chamber portion,
11. The pneumatic tire according to claim 1, wherein the plurality of first resonators and the plurality of second resonators are arranged such that, at any position in the tread circumferential direction, when viewed in the tread width direction, either or both of the first air chamber portion and the second air chamber portion are present.

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