JP7033503B2 - tire - Google Patents

Description

The present invention relates to a tire.

Conventionally, in order to reduce the air column resonance sound generated between the running road surface and the groove of the tread tread of the tire when the vehicle is running, for example, a Helmholtz type resonator is applied to the tire mounted on the vehicle. Are known.
This Helmholtz-type resonator is provided with an air chamber formed by being separated from the traveling road surface by being closed when the tire tread is grounded on the traveling road surface. The air chamber volume and the like are set on the assumption that the tire will be closed when the tire is closed.

As a device provided with such a resonator, for example, a pneumatic tire of Patent Document 1 has been proposed.

Japanese Unexamined Patent Publication No. 2015-171835

However, in actual driving, not only when traveling on a smooth road surface, but also when traveling on a rough road surface including unevenness, steps, etc., an air chamber partitioned from the traveling road surface is predetermined. It may not be the volume. In addition, an unexpected gap may occur between the vehicle and the road surface, the air chamber itself may not be formed, and the resonator may not function sufficiently. In these cases, the air column resonance sound cannot be sufficiently reduced.
Therefore, an object of the present invention is to provide a tire capable of reliably reducing air column resonance noise when the vehicle is running.

In order to achieve the above object, in the tire according to the present invention, at least one side in the tire width direction is partitioned on the tread tread by three or more circumferential main grooves continuously extending in the tire circumferential direction and the circumferential main groove. In addition, a tire having a plurality of land portions, at least in the intermediate land portion adjacent to the innermost side in the tire width direction of the circumferential main groove on the outermost side in the tire width direction, among the plurality of land portions. A resonator including a sub-groove terminating in the intermediate land portion and at least one branch groove communicating the sub-groove with the circumferential main groove, wherein the sub-groove in the resonator is a tread tread. It is characterized in that the opening width in the above is composed of only a hidden groove portion narrower than the groove width of the groove bottom. According to the tire according to the present invention, the air column resonance noise can be reliably reduced when the vehicle is running.

Here, in the present specification, the "tread tread" means that a tire assembled on a rim and filled with a predetermined internal pressure comes into contact with the road surface when the tire is rolled with a maximum load applied. It means the outer peripheral surface over the entire circumference of the tire, and the "tread ground contact end" means the end of the tread tread in the tire width direction.

Further, in the present specification, the "opening width", the "groove width" and the like refer to the width measured along the direction orthogonal to the extending direction of the groove in the following reference state. Hereinafter, unless otherwise specified, the dimensions of each element such as a groove shall be measured in the reference state.

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

The above "rim" is an industrial standard that is effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) JATMA YEAR BOOK, and in Europe, ETRTO (The European Tyre and Rim). STANDARDS MANUAL of Technical Organization), standard rim in applicable size (Measuring Rim in STANDARDS MANUAL of ETRTO) described in or in the future in YEAR BOOK of TRA (The Tire and Rim Association, Inc.) in the United States. , Design Rim in TRA's YEAR BOOK (ie, "rim" above includes sizes that may be included in the industry standards in the future in addition to current sizes. "Sizes to be stated in the future" As an example of, the size described as "FUTURE DEVELOPMENTS" in the STANDARDS MANUAL 2013 edition of ETRTO can be mentioned.) However, if the size is not described in the above industrial standard, it corresponds to the bead width of the tire. A rim with a wide width. The "predetermined 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 described in the above JATMA YEAR BOOK, etc., and is described in the above industrial standard. In the case of a size without tires, the "predetermined internal pressure" means the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle equipped with tires. Further, the "maximum load" means a load corresponding to the above maximum load capacity. The air referred to here can be replaced with an inert gas such as nitrogen gas or the like.

In the tire of the present invention, the groove width of the groove bottom of the sub-groove in the resonator in the intermediate land portion located in the half of the inside of the vehicle mounted with respect to the tire equatorial plane is such that one side in the tire circumferential direction is the other side. Wider is preferred. According to this configuration, the drainage efficiency due to the pump effect can be improved.

In the tire of the present invention, it is preferable that the groove width of the groove bottom gradually decreases from one side in the tire circumferential direction to the other side. According to this configuration, the drainage efficiency due to the pump effect can be further improved.

In the tire of the present invention, the inclination angle of the sub-groove in the resonator of the intermediate land portion located on the inner half of the vehicle mounting with respect to the tire equatorial plane with respect to the tire circumferential direction is the vehicle with respect to the tire equatorial plane. It is preferable that the sub-groove in the resonator in the intermediate land portion located in the outer half of the mounting is larger than the inclination angle with respect to the tire circumferential direction. According to this configuration, uneven wear resistance can be improved and deterioration of turning performance can be suppressed.

In the tire of the present invention, the opening in the tread tread of the sub-groove in the resonator in the intermediate land portion located in the half portion inside the vehicle mounting with respect to the equatorial plane of the tire is bent and extended. , Is preferable. According to this configuration, the drainage property of the tire can be improved.

According to the present invention, it is possible to provide a tire capable of reliably reducing air column resonance noise when the vehicle is running.

It is a partially developed view of the tread tread of the tire which concerns on one Embodiment of this invention. It is a partially enlarged view of the intermediate land part provided with the resonator shown in FIG. 1. It is a partially enlarged view of the intermediate land part provided with the other resonator shown in FIG. 1. It is sectional drawing which follows the depth direction of the resonator shown in FIG. It is explanatory drawing which shows the relationship between the ground contact line and the auxiliary groove in the tread tread of FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a partially developed view showing a tread tread 11 of a tire 10 according to an embodiment of the present invention. Although a part of the illustration is omitted, the tire 10 of the present embodiment includes a carcass having a radial structure extending in a toroidal shape between the bead portions, a belt arranged on the outer side of the tread portion of the carcass in the tire radial direction, and a belt. It is provided with a tread rubber which is arranged on the outer side in the tire radial direction to form the tread tread surface 11.

As shown in FIG. 1, the tire 10 of the present embodiment has three or more circumferential main grooves 12 continuously extending in the tire circumferential direction on the tread tread 11, and at least one of the tire width directions by the circumferential main groove 12. It has a plurality of land portions 13 whose sides are partitioned.

In the present embodiment, the tire 10 has five land portions 13 in which at least one side in the tire width direction is partitioned by four circumferential main grooves 12. More specifically, on the tread tread 11, a central land portion 13a partitioned by two circumferential main grooves 12a and 12b adjacent to each other with the tire equatorial plane CL in between, and a tire half on one side of the tire equatorial plane CL. The intermediate land portion 13b partitioned by the two circumferential main grooves 12a and 12c located in the portion HA (left side in the drawing in FIG. 1), the ground contact end TE of the tire half portion HA, and the circumference of the ground contact end TE side. Two circumferential main grooves 12b extending to the shoulder land portion 13c partitioned by the directional main groove (shoulder main groove) 12c and the tire half HB (right side in the drawing in FIG. 1) on the other side of the tire equatorial plane CL. It has an intermediate land portion 13d partitioned by 12d, and a shoulder land portion 13e partitioned by a ground contact end TE of the tire half HB and a circumferential main groove (shoulder main groove) 12d on the ground contact end TE side. ing.
Here, the tire half HA is a vehicle mounting inner portion that is inside (indicated as IN side in FIG. 1) when the tire 10 is mounted on the vehicle, and the tire half HB is the vehicle mounting inner portion when the tire 10 is mounted on the vehicle. This is the vehicle-mounted outer portion that becomes the outside (indicated as the OUT side in FIG. 1) (the same applies to the IN side and the OUT side in FIGS. 2, 3 and 5).

In the present embodiment, four circumferential main grooves 12 are provided, but the present invention is not limited to this, and three or more, such as five, may be provided.
The circumferential main grooves 12 (12a, 12b, 12c, 12d) in the tire 10 all extend linearly and continuously along the tire circumferential direction, but in other examples, they are zigzag or wavy. It can be an extended form other than a linear shape such as. Further, the land portion 13 (13a, 13b, 13c, 13d, 13e) in this example is a rib-shaped land portion continuously extending in the tire circumferential direction, but in another example, it is a block land portion or the like. can do.

The tire 10 of the present embodiment has an intermediate land portion 13 (13b, 13b, which is adjacent to at least the outermost circumferential main groove 12 (12c, 12d) in the tire width direction inside the tire width direction among the plurality of land portions 13. 13d) is a resonator (in the example shown in FIG. 1) including a sub-groove 14 terminated in the intermediate land portion 13 and at least one branch groove 15 communicating the sub-groove 14 and the circumferential main groove 12. , Helmholtz type resonator) 16.
In the present embodiment, the resonator 16 is composed of two types of resonators 16a and 16b, and in the example shown in FIG. 1, one resonator 16a is one of the two land portions 13b and 13d. The other intermediate land portion 16a is provided in the intermediate land portion 13b of the above, and the other intermediate land portion 13d of the two land portions 13b and 13d, respectively. The resonator 16a has an auxiliary groove 14a and two branch grooves 15a terminated in the intermediate land portion 13b, and the resonator 16b has an auxiliary groove 14b and two branch grooves 15b terminated in the intermediate land portion 13d, respectively. Includes.
That is, the inner intermediate land portion 13b on the inner side of the vehicle mounted when the tire 10 of the present embodiment is mounted has an auxiliary groove 14a, and the outer intermediate land portion 13d on the outer side of the vehicle mounted when the tire 10 is mounted on the vehicle. It has an auxiliary groove 14b.

Further, in the tire of the present invention, the resonator 16 may be configured to include only one of the two branch grooves 15 (15a, 15b). That is, the resonator 16 communicates only with the circumferential main groove 12 on one side in the tire width direction that divides the land portion 13, for example, the sub-groove 14a of the intermediate land portion 13b is the circumferential main groove 12a or the circumferential direction. The main groove 12c and the sub-groove 14b of the intermediate land portion 13d may be configured to communicate with the circumferential main groove 12b or the circumferential main groove 12d. Further, in the tire of the present invention, the resonator 16 may be configured to include three, four, or more branch grooves 15.

In the present embodiment, the branch groove 15 preferably has a groove width of 0.4 to 1.2 mm, more preferably 0.5 to 0.7 mm on the tread tread surface 11. If the groove width is 0.4 mm or more, the branch groove 15 does not close even when the tread tread surface 11 is in contact with the ground, so that the function of the resonator 16 can be exhibited. If the groove width is 1.2 mm or less, the branch groove 15 can be exhibited. It is possible to secure the rigidity of the land portion around the groove 15 and suppress uneven wear.
The branch groove 15 is always open.

In the resonator 16 (16a, 16b), the sub-grooves 14 (14a, 14b) have a shape extending in the tire circumferential direction, that is, a shape in which the tire circumferential length is larger than the tire width direction length. Further, the groove volume of the sub-groove 14 is larger than the groove volume of the branch groove 15 (15a, 15b) connected to the sub-groove 14.

In the present embodiment, in the resonator 16a, the end portion of the sub-groove 14 on one side in the tire circumferential direction (upper side in the drawing in FIG. 1) has a circumferential main groove 12c and a sub-groove by one of the two branch grooves 15a. The end portion of the tire 14 on the other side in the circumferential direction (lower side in the drawing in FIG. 1) communicates with the main groove 12a in the circumferential direction by the other of the two branch grooves 15a. Further, in the resonator 16b, the end portion of the sub-groove 14 on one side in the tire circumferential direction (upper side in the drawing in FIG. 1) has a circumferential main groove 12d and a tire of the sub-groove 14 due to one of the two branch grooves 15b. The end portion on the other side in the circumferential direction (lower side in the drawing in FIG. 1) communicates with the main groove 12b in the circumferential direction by the other of the two branch grooves 15b.
However, in the tire of the present invention, the branch groove 15 may be provided in a portion other than the tire circumferential end portion of the sub-groove 14, for example, the tire circumferential central portion of the sub-groove 14.

2 and 3 are partially enlarged views of the tread tread 11 shown in FIG. 1, FIG. 2 shows an enlarged peripheral portion of the resonator 16a and the resonator 16a, and FIG. 3 shows the resonator 16b and the resonance. The peripheral part of the vessel 16b is enlarged and shown.
The sub-groove 14 of the resonator 16 of the present embodiment includes only a hidden groove portion in which the opening width a of the tread tread 11 is narrower than the groove width of the groove bottom.
More specifically, the sub-grooves 14 (14a, 14b) of the resonator 16 (16a, 16b) are in the tread tread 11 of the openings O (Oa, Ob) in which all of the grooves open into the tread tread 11. It is composed of hidden groove portions G (Ga, Gb) whose opening width a is narrower than the groove bottom width b, which is the groove width of the groove bottom. In FIGS. 1 to 3, the groove wall of the hidden groove portion G (Ga, Gb) that does not appear on the tread tread 11 is shown by a hidden line (broken line).

Here, the opening O (Oa, Ob) that opens to the tread tread 11 is located substantially at the center of the groove opening width over the entire length direction of the hidden groove G (Ga, Gb).
Further, the opening width a refers to the distance between the openings O (Oa, Ob) in the tread tread 11 in the orthogonal direction to the opening edges on both sides in the opening extending direction, and the groove bottom width b is the groove on both sides in the groove bottom extending direction. The distance between orthogonal directions to the wall.
A plurality of resonators 16a including the sub-grooves 14a and a plurality of resonators 16b including the sub-grooves 14b are arranged at substantially equal intervals in the tire circumferential direction.

Since the sub-groove 14 of the resonator 16 is composed of only the hidden groove portion G, the sub-groove 14 can be reliably closed even when the tire 10 travels on a rough road surface including irregularities and steps. As a result, the air chamber partitioned from the traveling road surface can be made to have a predetermined volume, and an unexpected gap is generated between the air chamber and the traveling road surface so that the air chamber itself is not formed as much as possible. It can be made less likely to occur.
Therefore, regardless of the state of the traveling road surface, the provided resonator 16 functions reliably, and the air column resonance sound can be reliably reduced when the vehicle is traveling.

In the present embodiment, the groove width of the groove bottom of the auxiliary groove 14 in the resonator 16 of the intermediate land portion 13 located on the inner half of the vehicle mounting with respect to the tire equatorial plane CL is such that one side in the tire circumferential direction is the other side. Wider.
As shown in FIG. 2, the sub-groove 14a of the resonator 16a located in the intermediate land portion 13b located in the half HA (left side in the drawing in FIG. 1) inside the vehicle mounting with respect to the tire equatorial plane CL, that is, The groove bottom width b, which is the groove width of the groove bottom of the hidden groove portion Ga, has one side (upper side in the drawing) in the tire circumferential direction communicating with the circumferential main groove 12c via the branch groove 15a via the branch groove 15a. It is wider than the other side (lower side in the drawing) in the tire circumferential direction communicating with the circumferential main groove 12a.
Similarly, as shown in FIG. 3, the sub-groove 14b of the resonator 16b located in the intermediate land portion 13d located on the half HB outside the vehicle mounting with respect to the tire equatorial plane CL (in FIG. 1, the right side in the drawing). That is, the groove bottom width b, which is the groove width of the groove bottom of the hidden groove portion Gb, has a branch groove 15b on one side (upper side of the drawing) in the tire circumferential direction communicating with the circumferential main groove 12d via the branch groove 15b. It is wider than the other side (lower side in the drawing) in the tire circumferential direction communicating with the circumferential main groove 12b via the tire.
As described above, in the tire 10 of the present embodiment, the groove width (groove bottom width b) of the groove bottom of the sub-grooves 14 (14a, 14b) has a configuration in which one side in the tire circumferential direction is wider than the other side. There is.

In the present embodiment, the groove width of the groove bottom gradually decreases from one side in the tire circumferential direction to the other side.
As shown in FIG. 2, the sub-groove 14a of the resonator 16a located in the intermediate land portion 13b, that is, the groove bottom width b, which is the groove width of the groove bottom of the hidden groove portion Ga, is circumferential through the branch groove 15a. Gradually from one side of the tire circumferential direction communicating with the directional main groove 12c (upper side of the drawing) toward the other side of the tire circumferential direction communicating with the circumferential main groove 12a via the branch groove 15a (lower side of the drawing). It is gradually decreasing to shrink.
Similarly, as shown in FIG. 3, the sub-groove 14b of the resonator 16b located in the intermediate land portion 13d, that is, the groove bottom width b which is the groove width of the groove bottom of the hidden groove portion Gb has a branch groove 15b. From one side in the tire circumferential direction (upper side in the drawing) communicating with the circumferential main groove 12d via the branch groove 15b toward the other side in the tire circumferential direction communicating with the circumferential main groove 12b via the branch groove 15b (lower side in the drawing). , It is gradually decreasing so as to gradually shrink.
More specifically, in the hidden groove portion G of the present embodiment, in the plan view of the tread tread 11, one side (upper side in the drawing) in the tire circumferential direction has a wider groove bottom width b than the other side (lower side in the drawing). It has a wedge shape.

The sub-groove 14 of the present embodiment is inclined and extends with respect to the tire circumferential direction, and one side of the tire circumferential direction is arranged inside the vehicle mounting and the other side is arranged outside the vehicle mounting.
The hidden groove portion G (Ga) of the present embodiment shown in FIG. 2 and the hidden groove portion G (Gb) of the present embodiment shown in FIG. 3 have an arc shape in which the entire shape is curved in a bow shape in a plan view of the tread tread 11. One side of the tire circumferential direction (upper side in the drawing) is located inside the vehicle mounted inside the tire width direction when the tire is mounted on the tire vehicle, and the tire is located on the outside of the vehicle mounted outside the tire width direction when the tire vehicle is mounted. It is inclined and extends with respect to the tire circumferential direction so that the other side in the circumferential direction (lower side in the drawing) is located.

In the present embodiment, the inclination angle of the sub-groove 14 in the resonator 16 of the intermediate land portion 13 located in the inner half of the vehicle mounting with respect to the tire equatorial plane CL with respect to the tire circumferential direction is the inclination angle with respect to the tire equatorial plane CL. It is larger than the inclination angle of the auxiliary groove 14 in the resonator 16 of the intermediate land portion 13 located in the outer half of the vehicle mounting with respect to the tire circumferential direction.
In the present embodiment, the sub-groove 14a of the resonator 16a, that is, the hidden groove portion, located in the intermediate land portion 13b located on the half HA (left side in the drawing in FIG. 1) inside the vehicle mounting with respect to the tire equatorial plane CL. The inclination angle of Ga with respect to the tire circumferential direction is the sub-groove 14b in the resonator 16b of the intermediate land portion 13d located on the half HB (right side in the drawing in FIG. 1) on the outer side of the vehicle mounting with respect to the tire equatorial plane CL, and the tire. It is larger than the tilt angle with respect to the circumferential direction.

In the present embodiment, the inclination angle of the hidden groove portion G (Ga, Gb) is preferably 10 to 60 °, more preferably 35 to 45 ° with respect to the tire circumferential direction. This makes it possible to further improve the drainage performance due to the pump effect.
Here, the inclination angle of the hidden groove portion G (Ga, Gb) is one side (Oa, Ob) of the opening portion O (Oa, Ob) of the hidden groove portion G (Ga, Gb) in the plan view of the tread tread 11 in the tire circumferential direction. The straight line connecting the end portion on the upper side of the drawing and the end portion on the other side (lower side in the drawing) is an angle formed with the tire circumferential direction line (tire equatorial plane CL). That is, the straight line connecting both ends in the length direction of the opening O (Oa, Ob) located substantially in the center of the groove opening width over the entire length direction of the hidden groove G (Ga, Gb) is the tire circumferential direction. The angle between the line and the line.

In the present embodiment, the sub-groove 14 of the resonator 16, that is, the hidden groove portion G is treaded by an opening O (Oa, Ob) in which substantially the entire groove longitudinal direction passes through the groove width b direction substantially center of the hidden groove portion G. It is open to the tread 11.
The opening width a of the opening O (Oa, Ob) of the hidden groove G (Ga, Gb) is preferably 0.2 to 0.7 mm, more preferably 0.3 to 0.5 mm. .. If the opening width a is 0.2 mm or more, the mold for forming the hidden groove portion G can be easily pulled out during tire manufacturing, and if it is 0.7 mm or less, the hidden groove portion G can be easily pulled out when the tire touches the ground. Since the opening portion O of the tire is easily closed and the groove walls partitioning the hidden groove portion G support each other, the rigidity (particularly, shear rigidity) of the intermediate land portion 13 on which the resonator 16 is formed is more preferably maintained. Because it can be done. The opening O does not necessarily have to be open, and may be completely closed depending on the situation.

Further, the groove depth (length along the normal direction of the tread tread 11) d of the hidden groove portion G (Ga, Gb) is preferably 6.0 to 9.0 mm, preferably 7.0 to 8.0 mm. Is more preferable. When the groove depth d is 6 mm or more, the groove depth of the groove bottom side portion f becomes a sufficient depth, and it becomes easy to secure the groove volume of the sub-groove 14, and when the groove depth d is 9 mm or less, the opening portion. The rigidity of the side portion e can be more preferably secured.
The groove depth d is formed to be constant over the entire hidden groove portion G.

In the present embodiment, the opening O in the tread tread 11 of the sub-groove 14 in the resonator 16 of the intermediate land portion 13 located in the half inside the vehicle mounting with respect to the tire equatorial plane CL is bent and extends. ing.
In the present embodiment, the openings O (Oa, Ob) in the tread tread 11 of the hidden groove G (Ga, Gb) are convex in the tire circumferential direction in the plan view of the tread tread 11, as shown in FIGS. It has, for example, an acute-angled bent portion (convex on the upper side of the drawing). This bent portion forms a protruding end portion c that forms a tongue piece and is easily deformed on the tread tread 11 facing the opening O (Oa, Ob).
As described above, in the tire 10 of the present embodiment, the opening O in the tread tread 11 of the sub-grooves 14 (14a, 14b) is bent and extends.

FIG. 4 is a cross-sectional view of a surface orthogonal to the extending direction of the sub-groove 14 (14a, 14b) showing the sub-groove 14 (14a, 14b) of the resonator 16 (16a, 16b).
As shown in FIG. 4, in the present embodiment, the cross-sectional shape of the sub-groove 14 composed of the hidden groove portion G (Ga, Gb) is such that the opening width a of the opening portion O (Oa, Ob) in the tread tread 11 is the hidden groove portion. It has a substantially flask shape, which is narrower (smaller) than the groove depth d of G and narrower (smaller) than the groove bottom width b, which is the groove width of the groove bottom.

As shown in FIG. 4, the hidden groove portion G in the resonator 16 is the same as the opening width a in the tread tread surface 11 in order from the tread tread surface 11 side in a cross-sectional view of a surface orthogonal to the extending direction of the sub-groove 14. The tread is composed of an opening side portion e having a groove width and a groove bottom side portion f having a groove width wider than the opening width a.
In this resonator 16, the groove width of the opening side portion e of the hidden groove portion G is constant, while the groove width of the groove bottom side portion f is the groove bottom side from the tread tread surface 11 side toward the groove bottom side. After gradually increasing to the vicinity of the middle of the portion f, it is maintained constant up to the bottom of the groove.

In the hidden groove portion G of the present embodiment, the groove bottom width b of the opening portion O is preferably 1.0 to 4.0 mm, more preferably 1.5 to 2.5 mm, and the opening side portion. e is preferably 1.0 to 4.0 mm, more preferably 2.0 to 3.0 mm, and the groove bottom side portion f is preferably 4 to 7 mm and 5 to 6 mm. Is more preferable.
If the groove bottom width b is 1.5 mm or more, the air chamber of the resonator 16 does not collapse even when the tire touches the ground, and the air chamber volume can be secured, so that the desired sound absorption performance can be exhibited. If it is 2.5 mm or less, it is possible to suppress the decrease in the rigidity of the land portion and the decrease in the steering stability. If the opening side portion e is 1.0 mm or more, turning wear near the opening end of the land portion can be suppressed, and if it is 4.0 mm or less, the wet (WET) performance in the middle stage of wear due to running can be suppressed. The decrease can be suppressed.
However, in the resonator of the present invention, the groove bottom side portion f of the hidden groove portion G has a shape in which the groove width gradually increases and decreases from the opening O side of the tread tread 11 toward the groove bottom side in the cross-sectional view. For example, it may have a circular shape, an elliptical shape, or a rhombic shape, or a shape (for example, a triangular shape or a semicircular shape) in which the groove width always gradually increases from the tread tread surface 11 toward the groove bottom side.

Further, in the resonator of the present invention, in the hidden groove portion G, the groove width gradually increases from the opening O side of the tread tread 11 toward the groove bottom side, so that the opening width a in the opening O of the tread tread 11 is increased. The configuration may be smaller than the groove width on the groove bottom side.

Subsequently, the action / effect of the tire 10 according to the present embodiment will be described.
In the tire 10, as described above, of the plurality of land portions 13, at least the outermost circumferential main groove 12 (12c, 12d) in the tire width direction is adjacent to the inner side in the tire width direction of the intermediate land portion 13 ( 13b, 13d) includes a resonator (shown in FIG. 1) including a sub-groove 14 terminating in the intermediate land portion 13 and at least one branch groove 15 communicating the sub-groove 14 and the circumferential main groove 12. In the example, the Helmholtz type resonator) 16 (16a, 16b) is provided, and the sub-groove 14 of the resonator 16 has a hidden groove portion G (Ga, Gb) in which the opening width a in the tread tread 11 is narrower than the groove bottom width b. It consists only of.
Therefore, the resonator 16 provided in the tire 10 functions reliably, and the air column resonance sound generated between the traveling road surface and the circumferential main groove 12 (12a, 12b, 12c, 12d) when the vehicle is running is generated. It can be surely reduced.

In this tire 10, the sub-groove 14 of the resonator 16 is a hidden groove portion G in which the opening width a of the opening portion O in the tread tread 11 is narrower than the groove bottom width b which is the groove width of the groove bottom. In the hidden groove portion G, the opening width a of the openings O (Oa, Ob) opened in the tread tread 11 is narrower than the groove bottom width b. Excessive reduction can be suppressed, and uneven wear in the tread can be suppressed.

In the resonator 16 having this configuration, since the air chamber volume can be sufficiently secured on the groove bottom side of the hidden groove portion G, the frequency band of the resonator 16 is maintained within an effective range for reducing the air column resonance sound. Uneven wear in the tread can be suppressed. Further, in the tire 10 provided with the resonator 16, the rigidity of the land portion 13 (intermediate land portions 13b, 13d in the present embodiment) on which the resonator 16 is formed is difficult to reduce, so that the steering is stable when the vehicle turns. It is possible to improve the sex.
In this tire 10, the groove bottom width b, which is the groove width of the groove bottom of the sub-groove 14 in the resonator 16 of the intermediate land portion 13 located in the half of the inner half of the vehicle mounting with respect to the tire equatorial plane CL, is the tire circumference. One side of the direction is wider than the other. Therefore, the water or the like in the hidden groove portion G can be smoothly discharged from the side having the wide groove bottom width b without stagnation, and the drainage efficiency due to the pump effect can be improved.
Further, when the groove bottom width b gradually decreases from one side to the other side in the tire circumferential direction, water or the like in the hidden groove portion G can be smoothly sent to the side having the wider groove bottom width b. , The discharge efficiency due to the pump effect can be further improved.

In the tire 10, the sub-groove 14 is inclined and extends with respect to the tire peripheral direction, and one side of the tire circumferential direction is arranged inside the vehicle mounting and the other side is arranged outside the vehicle mounting.
That is, the hidden groove portion G is inclined and extends with respect to the tire circumferential direction, and the one having the wide groove bottom width b is inside when the tire 10 is mounted on the vehicle, and the one not having the wide groove bottom width b (narrow). The side) is on the outside when the tire 10 is mounted on the vehicle. Therefore, the balance of the land portion 13 provided with the hidden groove portion G is improved.
Further, the inclination angle of the sub-groove 14 in the resonator 16 of the intermediate land portion 13 located in the half inside the vehicle mounting with respect to the tire equatorial plane CL with respect to the tire circumferential direction is the outside of the vehicle mounting with respect to the tire equatorial plane CL. The sub-groove 14 in the resonator 16 of the intermediate land portion 13 located in the half of the tire is larger than the inclination angle with respect to the tire circumferential direction, so that the vehicle is usually mounted with a stronger influence on the load applied during the turning of the vehicle. Since the groove width is narrower on the outer side of the tire, the groove volume of the hidden groove portion G can be reduced to maintain the rigidity of the land portion 13, the uneven wear resistance is improved, and the deterioration of turning performance is suppressed. be able to.

Further, by setting the inclination angle of the hidden groove portion G to 30 to 60 ° with respect to the tire circumferential direction, the pump effect can be surely exhibited.

In this tire 10, the sub-groove 14a of the resonator 16a, that is, the hidden groove portion, located in the intermediate land portion 13b located on the half HA (left side in the drawing in FIG. 1) inside the vehicle mounting with respect to the tire equatorial plane CL. The inclination angle of Ga with respect to the tire circumferential direction is the sub-groove 14b in the resonator 16b of the intermediate land portion 13d located on the outer half HB of the vehicle mounting with respect to the tire equatorial plane CL (in FIG. 1, the right side of the drawing), and the tire. It is larger than the tilt angle with respect to the circumferential direction.
That is, in the plan view of the tread tread 11, the hidden groove portion Ga of the inner intermediate land portion 13b has a larger inclination than the hidden groove portion Gb of the outer intermediate land portion 13d with respect to the tire circumferential direction (see FIG. 1).

In this way, the inclination angle with respect to the tire circumferential direction is made larger in the hidden groove portion Ga of the inner intermediate land portion 13b than in the hidden groove portion Gb of the outer intermediate land portion 13d, so that the hidden groove portion Ga of the inner intermediate land portion 13b The drainage performance can be made higher than the drainage performance of the hidden groove portion Gb of the outer intermediate land portion 13d, and the rigidity of the outer intermediate land portion 13d can be made higher than the rigidity of the inner middle land portion 13b.
The larger the inclination angle of the hidden groove G with respect to the tire circumferential direction, the shorter the path toward the circumferential main groove 12 (preferably the shortest distance), so that the drainage from the hidden groove G to the circumferential main groove 12 is more effective. Can be done. On the other hand, when the inclination angle of the hidden groove portion G with respect to the tire circumferential direction is small, the rigidity of the land portion 13 when deformed in the tire width direction can be increased, so that the effect of supporting each other on the tread tread 11 at the time of touchdown can be obtained. Can be demonstrated.

Therefore, in this tire 10, when the vehicle is turning (cornering), the inner intermediate land portion 13b on the in side where the tread contact pressure of the tire is low emphasizes drainage, and the outer middle on the out side where the tread contact pressure is high. The land portion 13d can be configured in an optimum arrangement with an emphasis on grip. Therefore, it is possible to improve the steering stability during turning of the vehicle while improving the drainage performance.

In the tire 10, the opening O in the tread tread 11 of the sub-groove 14 in the resonator 16 of the intermediate land portion 13 located in the half part inside the vehicle mounting with respect to the tire equatorial plane CL is bent and extends. ing.
That is, the opening O is bent instead of a straight line to form a complicated shape, and when the tire tread 11 touches the traveling road surface, it is easy to open due to the deformation of the protruding end portion c. , Water or the like in the hidden groove portion G is easily discharged to the outside of the hidden groove portion G. Since the tire can be discharged directly to the outside of the hidden groove portion G from the opening O in the tread tread 11, the drainage performance of the tire 10 can be improved. When the tire tread 11 touches the traveling road surface, the branch groove 15 is basically closed.

Further, in the tire 10, the hidden groove portion G has a groove width similar to the opening width a of the opening portion O in the tread tread 11 maintained in the inner direction in the tire radial direction (groove depth d direction) on the opening side. Since the portion e is provided, uneven wear in the tread around the resonator 16 can be more reliably suppressed.

Further, in this tire 10, the hidden groove portion G (that is, the sub-groove 14) communicates with the circumferential main groove 12 via the branch groove 15 communicating with the sub-groove 14, so that when the load of the tire 10 is rolled. The hidden groove portion G acts as a pump, and water or the like that has entered the hidden groove portion G can be efficiently discharged to the circumferential main groove 12. That is, when the load of the tire 10 is rolled, the groove wall of the hidden groove portion G collapses and pushes out the water in the hidden groove portion G. Therefore, the drainage property of the tire 10 can be improved.

Due to this pump effect, water and the like in the hidden groove portion G are discharged, but the hidden groove portion G is in the normal direction in the ground contact line in contact with the traveling road surface of the land portion 13 (tread tread 11) where the hidden groove portion G is located. Have been placed.
As shown in FIG. 5, the ground contact line L has an arc shape with a convex center in the tire width direction. This is because the outer diameter of the tire on the tread tread 11 is the longest at the center in the tire width direction (center line: CL) and the shortest at the end in the tire width direction. Therefore, it is effective to arrange the hidden groove portion G so that the extending direction of the hidden groove portion G is in the normal direction with respect to the ground contact line L, and the extending direction extension line n of the hidden groove portion G and the hidden groove portion G are arranged. The angle α (see FIG. 5) formed by the normal line m at the ground contact line L of the land portion 13 (tread tread 11) is preferably 0 ° or more and 45 ° or less, and 0 ° or more and 25 ° or less. Is more preferable. By setting such an angle α, the pump effect can be surely obtained.
The extension line n of the hidden groove portion G in the extending direction is one side of the opening portion O (Oa, Ob) of the hidden groove portion G (Ga, Gb) in the plan view of the tread tread 11 in the tire circumferential direction (upper side of the drawing). ) A straight line connecting the end and the other (lower side of the drawing) end.

Further, in the tire 10, a plurality of resonators 16 are arranged at intermediate land portions 13b and 13d at substantially equal intervals in the tire circumferential direction. Therefore, it is possible to reduce the air column resonance noise in the tire circumferential direction and suppress uneven wear in the tread as much as possible.
Further, when the resonators 16 are provided on the plurality of land portions 13, the air column resonance noise in the other circumferential main grooves 12 with which the provided resonators 16 communicate is also reduced, so that the air generated in the tire 10 is generated. The total sum of the pillar resonance sounds can be reduced.

As described above, as shown in FIG. 1, the tire 10 of the present embodiment has a resonator 16a having only a hidden groove portion Ga in the inner intermediate land portion 13b inside the vehicle mounting inside the tire 10 when the tire 10 is mounted on the vehicle. The sub-groove 14a of the above is provided in the outer intermediate land portion 13d on the outer side of the vehicle-mounted portion, which is the outer side when the vehicle is mounted, and the sub-groove 14b of the resonator 16b composed of only the hidden groove portion Gb is provided.
The tire of the present invention is not limited to the configuration of the tire 10 shown in FIG. 1, and at least one side in the tire width direction is partitioned on the tread tread 11 by a circumferential main groove 12 continuously extending in the tire circumferential direction. A sub-groove 14 having a plurality of land portions 13 and terminating in the land portion 13 and at least one branch groove 15 communicating the sub-groove 14 and the circumferential main groove 12 in at least one land portion 13. A tire comprising a resonator 16 comprising the May be good.
That is, in the tire of the present invention, the resonator 16 (16a, 16b) composed of only the hidden groove portion G has at least one land portion 13 (13a, 13b, 13c) such as one of the intermediate land portions 13b and 13d. , 13d, 13e). In this case, the two types of resonators 16a and 16b may be used alone or in combination.

10: Tire, 11: Tread tread, 12, 12a, 12b, 12c, 12d: Circumferential main groove, 13, 13a, 13b, 13c, 13d, 13e: Land, 13b, 13d: Intermediate land, 13c, 13e : Shoulder land, 14, 14a, 14b: Sub-groove, 15, 15a, 15b: Branch groove, 16, 16a, 16b: Resonator, CL: Tire equatorial plane, G, Ga, Gb: Hidden groove, HA: One Half tire on the side, HB: Half tire on the other side, L: Ground line, O, Oa, Ob: Opening, TE: Tread end, a: Opening width, b: Groove bottom width, c: Protruding end , D: Groove depth, e: Opening side part, f: Groove bottom side part, m: Normal line at ground line, n: Extension direction extension line, α: Normal line m and extension line n

Claims (5)

A tire having a tread tread having three or more circumferential main grooves continuously extending in the circumferential direction of the tire, and a plurality of land portions having at least one side in the tire width direction partitioned by the circumferential main grooves. ,
Of the plurality of land portions, at least an intermediate land portion adjacent to the inner side in the tire width direction of the circumferential main groove on the outermost side in the tire width direction, a sub-groove terminating in the intermediate land portion, and the sub-groove. A resonator comprising at least one branch groove, which communicates with the circumferential main groove,
The sub-groove in the resonator consists only of a hidden groove portion in which the opening width in the tread tread is narrower than the groove width in the groove bottom .
The groove width of the groove bottom of the sub-groove in the resonator in the middle land portion located in the half of the inside of the vehicle mounted with respect to the tire equatorial plane is characterized in that one side in the tire circumferential direction is wider than the other side. Tires. A tire having a tread tread having three or more circumferential main grooves continuously extending in the circumferential direction of the tire, and a plurality of land portions having at least one side in the tire width direction partitioned by the circumferential main grooves. ,
Of the plurality of land portions, at least an intermediate land portion adjacent to the inner side in the tire width direction of the circumferential main groove on the outermost side in the tire width direction, a sub-groove terminating in the intermediate land portion, and the sub-groove. A resonator comprising at least one branch groove, which communicates with the circumferential main groove,
The sub-groove in the resonator consists only of a hidden groove portion in which the opening width in the tread tread is narrower than the groove width in the groove bottom .
The inclination angle of the sub-groove in the resonator in the resonator located on the inner half of the vehicle mounted on the tire equatorial plane with respect to the tire circumferential direction is set on the outer half of the vehicle mounted on the tire equatorial plane. A tire, characterized in that the sub-groove in the resonator of the intermediate land portion located is larger than the inclination angle with respect to the tire circumferential direction . A tire having a tread tread having three or more circumferential main grooves continuously extending in the circumferential direction of the tire, and a plurality of land portions having at least one side in the tire width direction partitioned by the circumferential main grooves. ,
Of the plurality of land portions, at least an intermediate land portion adjacent to the inner side in the tire width direction of the circumferential main groove on the outermost side in the tire width direction, a sub-groove terminating in the intermediate land portion, and the sub-groove. A resonator comprising at least one branch groove, which communicates with the circumferential main groove,
The sub-groove in the resonator consists only of a hidden groove portion in which the opening width in the tread tread is narrower than the groove width in the groove bottom .
The opening in the tread tread of the sub-groove in the resonator in the intermediate land portion located in the inner half of the vehicle mounting with respect to the tire equatorial plane is characterized by bending and extending . tire. 2 . Or the tire according to 3 . The tire according to claim 1 or 4 , wherein the groove width of the groove bottom gradually decreases from one side in the tire circumferential direction to the other side.

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