RU2807769C1 - Tire - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: tread section has a plurality of longitudinal main grooves, a plurality of lug grooves, and a plurality of running sections. A particular running portion includes, on a surface of a ground contact patch, a plurality of slits extending in a direction intersecting the longitudinal main grooves and a plurality of narrow grooves extending in a direction intersecting the longitudinal main grooves and having a groove depth of 1.50 mm or less. In the central region in the lateral direction of the tire, sipes and narrow grooves have different directions extending in the circumferential direction of the tire as they extend from one side to the other side in the lateral direction. In both edge regions on the outer side relative to the central region in the lateral direction of the tire, the sipes and narrow grooves have the same direction extending in the circumferential direction of the tire as they extend from one side to the other side in the lateral direction.

EFFECT: improved braking performance on ice and driving performance on snow are achieved.

8 cl, 8 dwg, 2 tbl, 11 ex

Description

Technical field

The present invention relates to a tire, and in particular relates to a tire in which a plurality of sipes are located on a tread surface.

State of the art

In recent years, it has been expected that a non-studded tire will appear that has appropriate braking performance on ice and driving performance on snow. To improve braking performance on ice, this type of studless tire includes a plurality of sipes located on the tread surface of the running portion, and the sipes in one block are arranged separately (separated) in the lateral direction of the tire, which provides rigidity to the block and prevents snow or ice from clogging the sipes.

On the other hand, the above configuration leads to a local increase in the ground contact pressure in the portion where the sipes are separated in the tire lateral direction orthogonal to the tire circumferential direction, deteriorating the wear resistance performance under load. Thus, a known configuration is proposed in which a longitudinal groove extending in the circumferential direction of the tire is provided in a portion where sipes are divided in the tire transverse direction (for example, see JP 2018-34524 A).

Technical problem

Tires that include sipes in the same block, located separately in the transverse direction of the tire, have the potential to further improve braking performance on ice and driving performance on snow.

In view of the above, it is an object of the present invention to provide a tire that can provide improved braking performance on ice and driving performance on snow.

Solution

To solve the above-described problem and achieve the object, the tire according to an embodiment of the present invention includes, in a tread portion, a plurality of longitudinal main grooves extending in a circumferential direction of the tire, a plurality of lug grooves extending in a direction intersecting the longitudinal main grooves, and a plurality of running portions. , formed by longitudinal main grooves and located in the direction intersecting the longitudinal main grooves. A particular running portion, which is at least one of the running portions, includes on a surface of a ground contact patch a plurality of slits extending in a direction intersecting the longitudinal main grooves and a plurality of narrow grooves extending in a direction intersecting the longitudinal main grooves, and having a groove depth of 1.50 mm or less. In the central region in the lateral direction of the tire, sipes and narrow grooves have different directions extending in the circumferential direction of the tire as they extend from one side to the other side in the lateral direction. In both edge regions on the outer side relative to the central region in the lateral direction of the tire, the sipes and narrow grooves have the same direction extending in the circumferential direction of the tire as they extend from one side to the other side in the lateral direction. The particular tread portion includes a tread portion including at least one tread portion on the outer side in the lateral direction of the tire.

A particular running portion preferably includes a plurality of blocks formed by longitudinal main grooves and lug grooves.

The length of a particular running portion in the direction intersecting the longitudinal main grooves is taken to be 100%, and the length of the central region in the direction intersecting the longitudinal main grooves is preferably 60% or more and 80% or less.

The sipes preferably have an inclination angle relative to the tire circumferential direction of 45° or more and 80° or less.

The narrow grooves preferably have an inclination angle relative to the tire circumferential direction in the central region of 40° or more and 65° or less.

The narrow grooves preferably have an inclination angle relative to the tire circumferential direction in the edge regions of 50° or more and 80° or less.

The narrow grooves preferably have a groove depth of 0.05 mm or more and 1.50 mm or less and a groove width of 0.10 mm or more and 0.80 mm or less, and the distance between narrow grooves adjacent to each other is preferably 0 .50 mm or more and 2.00 mm or less.

The end of the narrow grooves in the central region is preferably connected to the end of the narrow grooves in the edge regions.

Advantages of the invention

A tire in accordance with an embodiment of the present invention can provide improved braking performance on ice and driving performance on snow.

Brief description of drawings

Fig. 1 is a plan view showing the tread surface of a pneumatic tire according to the present embodiment;

Fig. 2 is an enlarged view illustrating one shoulder running portion on a tread surface of a pneumatic tire according to the present embodiment;

Fig. 3 is an enlarged view illustrating one second running portion on a tread surface of a pneumatic tire according to the present embodiment;

Fig. 4 is an enlarged view illustrating one central running portion on a tread surface of a pneumatic tire according to the present embodiment;

Fig. 5 is an enlarged view illustrating another central running portion on the tread surface of a pneumatic tire according to the present embodiment;

Fig. 6 is an enlarged view illustrating another second running portion on a tread surface of a pneumatic tire according to the present embodiment;

Fig. 7 is an enlarged view illustrating another shoulder running portion on a tread surface of a pneumatic tire according to the present embodiment; And

Fig. 8 is a plan view illustrating a tread surface of a pneumatic tire according to another embodiment.

Description of Embodiments of the Invention

Embodiments of the present invention will be described in detail below with reference to drawings. However, the present invention is not limited to the following embodiments. Components of these embodiments include elements that are substantially identical, or elements that can be replaced or easily created by one of ordinary skill in the art.

Below will be a description of the pneumatic tire of the present invention. In the following description, the term “tire radial direction” refers to the direction orthogonal to the rotation axis of the pneumatic tire; "inner side relative to the tire radial direction" means the side facing the rotation axis in the tire radial direction; and the term “tire radial outer side” means the side away from the axis of rotation in the tire radial direction. In addition, the term "tire circumferential direction" denotes a longitudinal direction with the axis of rotation as the center line. In addition, the term "tire lateral direction" refers to the direction parallel to the axis of rotation; the term "inner side in the lateral direction of the tire" refers to the side facing the equatorial plane (equatorial line of the tire) in the lateral direction of the tire; and the term “outer side in the tire lateral direction” refers to the side facing the side opposite the equatorial plane of the tire in the lateral direction of the tire. Note that “tire equatorial plane” refers to a plane orthogonal to the rotation axis of the pneumatic tire passing through the center of the width of the pneumatic tire.

In FIG. 1 is a plan view of a tread surface of a pneumatic tire according to the present embodiment. In FIG. 1, the reference numeral CL denotes the equatorial plane of the tire, and the reference numeral T denotes the edges of the tire ground contact patch. Moreover, the pneumatic tire 1 according to the present embodiment (hereinafter also referred to simply as "tire 1") is pointed in the installation direction relative to the vehicle, and in the example shown in FIG. 1, it has an asymmetrical tread pattern on the left on the equatorial plane CL of the tire. It should be noted that in FIG. 1, the ground contact area T, illustrated on the outer side in the lateral direction of the tire, includes a so-called sidewall portion.

The ground contact edge T is defined as the location of the maximum width in the tire axial direction of the contact surface between the tire 1 and the flat plate when the tire 1 is mounted on a certain rim, inflated to a certain internal pressure, positioned perpendicular to the flat plate in a static state and loaded in accordance with a certain load.

The term "specific wheel" means "applicable wheel" as defined by the Japan Automobile Tire Manufacturers Association (JATMA), "project wheel" as defined by the Tire and Wheel Association (TRA), or "measuring wheel" as defined by the European Tire and Wheel Technical Organization ( ETRTO). In addition, the term “specified inflation pressure” means the “maximum air pressure” as defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” as defined by TRA, or “INFLATION PRESSURE” as defined by ETRTO. Additionally, the term "Specified Load" means the "maximum load capacity" as defined by JATMA, the maximum value described in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" as defined by TRA, or the "ALLOWABLE LOAD" as defined by ETRTO. However, in the case of JATMA for a tire used in passenger vehicles, the specified inflation pressure is an air pressure of 180 kPa and the specified load is 88% of the maximum permissible load.

The tread portion 10 of the tire 1 is made of a rubber material (tread rubber) and is located on the outermost side of the tire 1 in the tire radial direction, its surface being the contour of the tire 1. The surface of the tread portion 10 forms a tread surface 12, which is a contact surface with the road surface when the vehicle (not shown) on which the tire 1 is mounted is driven.

The tire 1 on the tread surface 12 includes a plurality of longitudinal main grooves 21, 22, 23, 24 and 25 extending in a circumferential direction of the tire, a plurality of tread portions 31, 32, 33, 34, 35 and 36 formed by the longitudinal main grooves 21 , 22, 23, 24 and 25, a plurality of lug grooves 311, 321, 322, 331, 351 and 361 located on each of the running sections 31, 32, 33, 34, 35 and 36, a plurality of slots 4 located on each of running sections 31 to 36, and narrow grooves 5 located on each of the running sections 31, 32, 33, 34, 35 and 36. Here, longitudinal main grooves 21, 22, 23, 24 and 25 designate grooves extending in a circumferential direction tires and necessarily having a wear indicator as specified by JATMA, which generally have a groove width of 5.0 mm or more and a groove depth of 6.5 mm or more. The lug grooves 311, 321, 322, 331, 341 and 351 designate side grooves extending in a direction intersecting the longitudinal main grooves (in the tire transverse direction), which generally have a groove width of 1.0 mm or more and a groove depth of 3 .0 mm or more. The sipes 4 refer to cuts formed on the tread surface 12, which typically have a sipes width of less than 1.0 mm and a sipes depth of 2.0 mm or more and thus close when the tire contacts the ground. The narrow grooves 5 are shallow grooves formed on the tread surface 12. The narrow grooves 5 have a shallower groove depth than the slots 4. The narrow grooves 5 generally have a groove depth of 0.05 mm or more and 1.50 mm or less and a groove width of 0.10 mm or more and 0.80 mm or less, and the distance (pitch) between narrow grooves 5 adjacent to each other is generally 0.50 mm or more and 2.00 mm or less. As described above, the tire 1 according to the present embodiment is a studless tire provided with sipes 4 and narrow grooves 5 on the tread surface 12. The configurations of the slots 4 and narrow grooves 5 will be described below.

A plurality (five in FIG. 1) of longitudinal main grooves 21, 22, 23, 24 and 25 extending in the circumferential direction of the tire are provided on the tread surface 12 at predetermined intervals in the lateral direction of the tire. In the present embodiment, as illustrated in FIG. 1, the longitudinal main grooves 21, 22, 23, 24 and 25 are arranged in this order from the inner side in the vehicle transverse direction to the outer side in the vehicle transverse direction. The longitudinal main grooves 23 are the longitudinal main groove closest to the equatorial plane CL of the tire. In the present embodiment, two longitudinal main grooves 21, 22 are provided on the inner side in the transverse direction of the vehicle, and two longitudinal main grooves 24, 25 are provided on the outer side in the transverse direction of the vehicle. Here, the inner side in the vehicle lateral direction and the outer side in the vehicle lateral direction are indicated as references relative to the lateral direction of the vehicle when the tire 1 is installed on the vehicle. In addition, two longitudinal main grooves 21, 25 on the outermost side in the tire lateral direction are defined as shoulder main grooves, and four longitudinal main grooves 22, 23 and 24 on the innermost side in the lateral direction of the tire are defined as center main grooves.

In the example in FIG. 1, each of the longitudinal main grooves 21, 25, which are shoulder main grooves, has a straight shape in which the width of the groove does not change in the circumferential direction. Of the central main grooves, the longitudinal main grooves 22, 24 are formed in a zigzag shape that periodically bends in the lateral direction of the tire while extending in the circumferential direction of the tire. Of the central main grooves, the longitudinal main groove 23 has a rectilinear shape. The longitudinal main groove 22, which is a central main groove on the inner side in the vehicle lateral direction, has a groove wall on the tire equatorial plane CL side having a rectilinear shape, in which the location of the groove wall in the tire lateral direction does not change, but has a groove wall on the side of the edge T of the ground contact patch, having a zigzag shape, which periodically bends in the transverse direction of the tire, while passing in the direction along the circumference of the tire. Here, the number of the longitudinal main grooves 21, 22, 23, 24 and 25 is not limited to the above, and four or less or six or more longitudinal main grooves may be arranged on the tread surface 12.

A plurality (six rows in FIG. 1) of tread sections 31, 32, 33, 34, 35 and 36 extending in the circumferential direction of the tire are formed on the tread surface 12 by five longitudinal main grooves 21, 22, 23, 24 and 25. B In the present embodiment, the running portions 31, 36, respectively, formed on the outer side in the transverse direction of the tire by the longitudinal main grooves 21, 25, which are shoulder main grooves, are defined as shoulder running portions. The running portion 32 formed by the longitudinal main grooves 21 and the longitudinal main groove 22, and the running portion 35 formed by the longitudinal main groove 24 and the longitudinal main groove 25, i.e. shoulder portions adjacent to the shoulder running portions 31, 36 on the inner side in the lateral direction of the tire through the shoulder main grooves are defined as second running portions. The running portion 33 formed by the longitudinal main grooves 22, 23, which are the central main grooves, and the running portion 34, formed by the longitudinal main grooves 22, 23, which are the central main grooves, are defined as the central running portions. The running portions 33, 34, which are the central running portions, are provided near the equatorial plane CL of the tire.

In the example in FIG. 1, the running portions 33, 34 are provided, which are two central running portions, but in the configuration with four longitudinal main grooves, one central running portion is formed. In the configuration with three longitudinal main grooves, the central running portion can also serve as a second running portion.

The running portions 31, 36, which are left and right shoulder running portions, include a plurality of lug grooves 311, 361, respectively. The lug grooves 311, 361 have one end respectively connected by an opening to the longitudinal main grooves 21, 25, which are shoulder main grooves, extend on the outer side in the transverse direction of the tire and have other ends ending in the area along the edge T of the ground contact patch. A plurality of lug grooves 311, 361 are provided in a repeating manner in the circumferential direction of the tire on the running portions 31, 36, which are the shoulder running portions, respectively. Thus, the running portions 31, 36, which are the shoulder running portions, are divided into a plurality of blocks (shoulder blocks) formed by the lug grooves 311, 361, respectively. A plurality of slots 4 and a plurality of narrow grooves 5 are formed in these respective blocks. The longitudinal narrow grooves 312, 362 extend in the circumferential direction of the tire and have some ends in the circumferential direction, respectively connected by openings with the lug grooves 311, 361, and other ends ending inside the blocks. Each of the circumferential groove 312 and the circumferential groove 362 has an end connected by an opening to lug grooves on different sides in the circumferential direction of the tire.

The second running portion 32 on the inner side in the lateral direction of the vehicle includes a plurality of lug grooves 321, 322 of two kinds. The lug groove 321 (first lug groove) has one end facing one end of the above-described lug groove 311 and connected by an opening to the shoulder main groove 21, and the other end ending inside the second running portion 32. The lug groove 322 (second lug groove) has one end connected by an opening to the central main groove 22, and the other end terminated within the second running portion 32. In the example of FIG. 1, one end of the lug groove 322 is connected by an opening to a corner portion of the central main groove 22 having a zigzag shape that projects toward the ground contact edge T side. Thus, the lug grooves 321, 322 have a semi-closed structure that does not intersect the second running portion 32. Moreover, these lug grooves 321, 322 are staggered (alternate) in the circumferential direction of the tire, each of them extending at an angle in one and the same direction in the circumferential direction of the tire, and they overlap with each other in the lateral direction of the tire. Thus, the second tread portion 32 is formed as a rib that is continuous in the tire circumferential direction without being separated by the lug grooves 321, 322 in the tire circumferential direction. A plurality of slits 4 and a plurality of narrow grooves 5 are formed on the second running portion 32.

The running portion 33, which is a central running portion, includes a plurality of lug grooves 331. Although in FIG. 1 only one lug groove 331 is illustrated, a plurality of lug grooves 331 are formed in the circumferential direction of the tire. The lug groove 331 is formed by extending in the transverse direction of the tire between the longitudinal main grooves 22, 23, which are two central main grooves, and has both corresponding ends connected by an opening to the longitudinal main grooves 22, 23, which are the central main grooves. The running portion 33, which is a central running portion, is formed into a plurality of blocks by a plurality of grooves 331, and a plurality of narrow grooves 332 and a plurality of slits 4 are provided in each block.

The running portion 34, which is a central running portion, includes a plurality of lug grooves 341. Although in FIG. 1 only one lug groove 341 is illustrated, a plurality of lug grooves 341 are formed in the circumferential direction of the tire. The lug groove 341 is formed by extending in the transverse direction of the tire between the longitudinal main grooves 23, 24, which are two central main grooves, and has both corresponding ends connected by an opening to the longitudinal main grooves 23, 24, which are the central main grooves. In the example in FIG. 1, one end of the lug groove 341 is connected by an opening to the corner portion of the longitudinal main groove 24, which is a central main groove having a zigzag shape that projects toward the equatorial plane side CL of the tire, and extends along the longitudinal direction of the short length portion of the longitudinal main groove 24, which is the central main groove. In addition, a lug groove 341 is provided with respect to every second corner portion, which forms a zigzag shape of the longitudinal main groove 24 representing the central main groove. The running portion 34, which is a central running portion, is formed into a plurality of blocks by a plurality of grooves 341, and a plurality of slots 4 and a plurality of narrow grooves 5 are provided in each block.

The second running portion 35 on the outer side in the lateral direction of the vehicle includes a plurality of lug grooves 351 and a plurality of longitudinal narrow grooves 352. The lug groove 341 extends in the lateral direction of the tire between the central main groove 23 and the shoulder main groove 24 adjacent to each other, and has one end connected by an opening to the central main groove 23, and the other end connected by an opening to the shoulder main groove 24. In the example of FIG. 1, one end of the lug groove 351 is connected by an opening to the corner portion of the central main groove 24 having a zigzag shape, which protrudes towards the side of the edge T of the ground contact patch, and the other end of the lug groove 351 is opposite to the above-described one end of the lug groove 351 and is connected by the opening with a shoulder main groove 25. The second running portion 35 is divided into a plurality of blocks by a plurality of lug grooves 351. In the example of FIG. 1, in these blocks, a longitudinal narrow groove 352 is formed in a zigzag shape, which periodically bends in the transverse direction of the tire while extending in the circumferential direction of the tire. The longitudinal narrow groove 352 is a narrow groove extending in the circumferential direction of the tire, and the groove width of the longitudinal narrow groove 352 is 1.0 mm or more and 3.0 mm or less. In addition, a plurality of slits 4 and a plurality of narrow grooves 5 are formed in the second running portion 35.

Note that the pneumatic tire 1 according to the present embodiment has a meridional cross-sectional shape similar to that of a known pneumatic tire. Here, the meridional cross-sectional shape of the pneumatic tire refers to the cross-sectional shape of the pneumatic tire as shown on a plane normal to the equatorial plane of the tire CL. The tire 1 according to the present embodiment has a bead portion, a sidewall portion, a shoulder portion, and an inner to outer tread portion 10 in the tire radial direction in the form of a tire meridional cross section not shown in the figure. Moreover, in the meridional cross section, for example, the tire 1 has a carcass layer that extends from the tread portion 10 to the tire bead portions on both sides and is wound around a pair of bead cores, and a belt layer and a reinforcing layer are formed on the carcass layers on the outer side at radial direction of the tire.

Next, the slits 4 and narrow grooves 5 formed in the running portions 31, 32, 33, 34, 35 and 36 will be described. In FIG. 2 is an enlarged view illustrating one shoulder tread portion on a tread surface of a pneumatic tire according to the present embodiment. In FIG. 3 is an enlarged view illustrating one second tread portion on a tread surface of a pneumatic tire according to the present embodiment. In FIG. 4 is an enlarged view illustrating one central running portion on a tread surface of a pneumatic tire according to the present embodiment. In FIG. 5 is an enlarged view illustrating another central running portion on a tread surface of a pneumatic tire according to the present embodiment. In FIG. 6 is an enlarged view illustrating another second running portion on a tread surface of a pneumatic tire according to the present embodiment. In FIG. 7 is an enlarged view illustrating another shoulder running portion on a tread surface of a pneumatic tire according to the present embodiment.

As described above, the running portion 31 illustrated in FIG. 2 is provided with slots 4 and narrow grooves 5 formed on the tread surface. As illustrated in FIG. 2, a plurality of sipes 4 extend along the lateral direction of the tire and are located adjacent to each other in the circumferential direction of the tire. The slits 4 extend in a direction along the line segment 102a. The line segment 102a is inclined with respect to each of the tire circumferential direction and the tire lateral direction. In addition, the sipes 4 are formed in a zigzag shape in which the opening portion of the tread surface 12 is continuously bent multiple times. For example, the line segment 102a is a line connecting the vertices of the corners on one side of the zigzag shape in the circumferential direction of the tire. The sipes 4 may be two-dimensional sipes whose shape in the tread portion 10 from the tread surface 12 to the inner side in the radial direction of the tire is a zigzag shape along the zigzag shape on the tread surface 12, or may be three-dimensional sipes further curved in addition to the zigzag shape. form. The angle (angle of inclination) formed by the slots 4 and the direction along the circumference of the tire is θa.

The narrow grooves 5 are grooves that have a shallower groove depth than the slots 4. The groove bottom shape of the narrow grooves 5 is not limited to a flat groove bottom, and the groove bottom may have a U-shape or a V-shape as viewed from, for example, cross-sectional view. As illustrated in FIG. 2, a plurality of narrow grooves 5 extend along the lateral direction of the tire and are located adjacent to each other in the circumferential direction of the tire. The narrow grooves 5 formed on the running portion 31 include narrow grooves 120a, 122a and 124a. Narrow grooves 120a, 122a and 124a are formed at different positions in the lateral direction of the tire. Narrow grooves 120a are formed in the central region 120a, i.e. at a central portion of the running portion 31 in the lateral direction of the tire. Narrow grooves 122a are formed in the edge region 122a on the inner side in the vehicle lateral direction relative to the central area 120a of the running portion 31. Narrow grooves 124a are formed in the edge area 124a on the outer side in the vehicle lateral direction relative to the central area 120a of the running portion 31. Central area 120a contacts edge regions 122a, 124a. The ends of the narrow grooves 120a on the inner side in the vehicle transverse direction are connected to the narrow grooves 122a, and their ends on the outer side in the vehicle transverse direction are connected to the narrow grooves 124a.

Here, the narrow grooves 120a, the narrow grooves 122a, and the narrow grooves 124a have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120a, narrow grooves 122a and narrow grooves 124a have different directions extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle. The angle (tilt angle) formed by the narrow grooves 120a and the tire circumferential direction is θ1. The angle (tilt angle) formed by the narrow grooves 122a and the circumferential direction of the tire is θ2. The angle (tilt angle) formed by the narrow grooves 124a and the circumferential direction of the tire is θ3. The tilt angle θ2 and the tilt angle θ3 are the same angle.

The narrow grooves 120a and sipes 4 have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120a and the slits 4 have different running directions in the circumferential direction when they extend from the outer side to the inner side in the transverse direction of the vehicle. In addition, the narrow grooves 122a, narrow grooves 124a and sipes 4 have the same running direction in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle.

As described above, the running portion 32 illustrated in FIG. 3 is provided with slots 4 and narrow grooves 5 formed on the tread surface. The basic shapes of the slots 4 and the grooves 5 are similar to those on the tread portion 31. The narrow grooves 5 formed on the tread portion 32 include narrow grooves 120b, 122b, and 124b. Narrow grooves 120b, 122b and 124b are formed at different positions in the lateral direction of the tire. Narrow grooves 120b are formed in the central region 120b, i.e. at a central portion of the running portion 32 in the tire lateral direction. Narrow grooves 122b are formed in the edge region 122b on the inner side in the vehicle lateral direction relative to the central area 120b of the running portion 32. Narrow grooves 124b are formed in the edge area 124b on the outer side in the vehicle lateral direction relative to the central area 120b of the running portion 32. Central area 120b contacts edge regions 122b, 124b. The ends of the narrow grooves 120b on the inner side in the vehicle transverse direction are connected to the narrow grooves 122b, and their ends on the outer side in the vehicle transverse direction are connected to the narrow grooves 124b.

Here, the narrow grooves 120b, the narrow grooves 122b and the narrow grooves 124b have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120b, narrow grooves 122b and narrow grooves 124b have different directions extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the vehicle lateral direction. The angle (tilt angle) formed by the narrow grooves 120b and the tire circumferential direction is θ1. The angle (tilt angle) formed by the narrow grooves 122b and the tire circumferential direction is θ2. The angle (tilt angle) formed by the narrow grooves 124b and the tire circumferential direction is θ3. The tilt angle θ2 and the tilt angle θ3 are the same angle.

The narrow grooves 120b and sipes 4 have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120b and the slits 4 have different directions extending in the circumferential direction when they extend from the outer side to the inner side in the transverse direction of the vehicle. In addition, the narrow grooves 122b, narrow grooves 124b and sipes 4 have the same direction extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle.

As described above, the running portion 33 illustrated in FIG. 4 is provided with slots 4 and narrow grooves 5 formed on the tread surface. The basic shapes of the slots 4 and narrow grooves 5 are similar to those in the tread portion 31. The narrow grooves 5 formed in the tread portion 33 include narrow grooves 120c, 122c, and 124c. Narrow grooves 120c, 122c and 124c are formed at different positions in the lateral direction of the tire. Narrow grooves 120c are formed in the central region 120c, i.e. at a central portion of the running portion 33 in the lateral direction of the tire. Narrow grooves 122c are formed in the edge region 122c on the inner side in the vehicle lateral direction relative to the central area 120c of the running portion 33. Narrow grooves 124c are formed in the edge area 124c on the outer side in the vehicle lateral direction relative to the central area 120c of the running portion 33. Central area 120c contacts edge regions 122c, 124c. The ends of the narrow grooves 120c on the inner side in the vehicle transverse direction are connected to the narrow grooves 122c, and their ends on the outer side in the vehicle transverse direction are connected to the narrow grooves 124c.

Here, the narrow grooves 120c, the narrow grooves 122c and the narrow grooves 124c have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120c, narrow grooves 122c and narrow grooves 124c have different directions extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle. Here, the angle (tilt angle) formed by the narrow grooves 120c and the tire circumferential direction is θ1. The angle (tilt angle) formed by the narrow grooves 122c and the tire circumferential direction is θ2. The angle (tilt angle) formed by the narrow grooves 124c and the tire circumferential direction is θ3. The tilt angle θ2 and the tilt angle θ3 are the same angle.

The narrow grooves 120c and sipes 4 have different inclination directions with respect to the circumferential direction of the tire and the lateral direction of the tire. This means that the narrow grooves 120c and the slits 4 have different directions extending in the circumferential direction as they extend from the outer side to the inner side in the transverse direction of the vehicle. In addition, the narrow grooves 122c, narrow grooves 124c and sipes 4 have the same direction extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle.

As described above, the running portion 34 illustrated in FIG. 5 is provided with slots 4 and narrow grooves 5 formed on the tread surface. The basic shapes of the slots 4 and the narrow grooves 5 are similar to those in the tread portion 31. The narrow grooves 5 formed in the tread portion 34 include narrow grooves 120d, 122d, and 124d. Narrow grooves 120d, 122d and 124d are formed at different positions in the lateral direction of the tire. Narrow grooves 120d are formed in the central region 120d, i.e. at a central portion of the running portion 34 in the lateral direction of the tire. Narrow grooves 122d are formed in the edge region 122d on the inner side in the vehicle lateral direction relative to the central area 120d of the running portion 34. Narrow grooves 124d are formed in the edge area 124d on the outer side in the vehicle lateral direction relative to the central area 120d of the running portion 34. Central area 120d contacts edge regions 122d, 124d. The ends of the narrow grooves 120d on the inner side in the vehicle transverse direction are connected to the narrow grooves 122d, and their ends on the outer side in the vehicle transverse direction are connected to the narrow grooves 124d.

Here, the narrow grooves 120d, the narrow grooves 122d and the narrow grooves 124d have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120d, the narrow grooves 122d and the narrow grooves 124d have different directions extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle. Here, the angle (tilt angle) formed by the narrow grooves 120d and the tire circumferential direction is θ1. The angle (tilt angle) formed by the narrow grooves 122d and the circumferential direction of the tire is θ2. The angle (tilt angle) formed by the narrow grooves 124d and the tire circumferential direction is θ3. The tilt angle θ2 and the tilt angle θ3 are the same angle.

The narrow grooves 120d and sipes 4 have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120d and the slits 4 have different directions extending in the circumferential direction when they extend from the outer side to the inner side in the transverse direction of the vehicle. In addition, the narrow grooves 122d, narrow grooves 124d and sipes 4 have the same direction extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the vehicle transverse direction.

As described above, the running portion 35 illustrated in FIG. 6 is provided with slots 4 and narrow grooves 5 formed on the tread surface. The basic shapes of the slots 4 and narrow grooves 5 are similar to those in the tread portion 31. The narrow grooves 5 formed in the tread portion 35 include narrow grooves 120e, 122e, and 124e. Narrow grooves 120e, 122e and 124e are formed at different positions in the lateral direction of the tire. Narrow grooves 120e are formed in the central region 120e, i.e. at a central portion of the running portion 35 in the lateral direction of the tire. Narrow grooves 122e are formed in the edge region 122e on the inner side in the lateral direction of the vehicle relative to the central area 120e of the running portion 35. Narrow grooves 124e are formed in the edge area 124e on the outer side in the lateral direction of the vehicle relative to the central area 120e of the running portion 35. Central area 120e contacts edge regions 122e, 124e. The ends of the narrow grooves 120e on the inner side in the vehicle transverse direction are connected to the narrow grooves 122e, and their ends on the outer side in the vehicle transverse direction are connected to the narrow grooves 124e.

Here, the narrow grooves 120e, the narrow grooves 122e and the narrow grooves 124e have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120e, narrow grooves 122e and narrow grooves 124e have different directions in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle. Here, the angle (tilt angle) formed by the narrow grooves 120e and the tire circumferential direction is θ1. The angle (tilt angle) formed by the narrow grooves 122e and the circumferential direction of the tire is θ2. The angle (tilt angle) formed by the narrow grooves 124e and the circumferential direction of the tire is θ3. The tilt angle θ2 and the tilt angle θ3 are the same angle.

The narrow grooves 120e and sipes 4 have different inclination directions with respect to the circumferential direction of the tire and the lateral direction of the tire. This means that the narrow grooves 120e and the slits 4 have different directions extending in the circumferential direction as they extend from the outer side to the inner side in the transverse direction of the vehicle. In addition, the narrow grooves 122e, narrow grooves 124e and sipes 4 have the same direction extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle.

As described above, the running portion 36 illustrated in FIG. 7 is provided with slots 4 and narrow grooves 5 formed on the tread surface. The basic shapes of the slots 4 and narrow grooves 5 are similar to those on the running portion 31.

The narrow grooves 5 formed on the running portion 36 include narrow grooves 120f, 122f and 124f. Narrow grooves 120f, 122f and 124f are formed at different positions in the lateral direction of the tire. Narrow grooves 120f are formed in the central region 120f, i.e. at a central portion of the running portion 36 in the lateral direction of the tire. Narrow grooves 122f are formed in the edge region 122f on the inner side in the vehicle lateral direction relative to the central area 120f of the running portion 36. Narrow grooves 124f are formed in the edge region 124f on the outer side in the vehicle lateral direction relative to the central area 120f of the running portion 36. Central area 120f contacts edge regions 122f, 124f. The ends of the narrow grooves 120f on the inner side in the vehicle transverse direction are connected to the narrow grooves 122f, and their ends on the outer side in the vehicle transverse direction are connected to the narrow grooves 124f.

Here, the narrow grooves 120f, the narrow grooves 122f and the narrow grooves 124f have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120f, the narrow grooves 122f and the narrow grooves 124f have different directions extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the lateral direction of the vehicle. Here, the angle (tilt angle) formed by the narrow grooves 120f and the tire circumferential direction is θ1. The angle (tilt angle) formed by the narrow grooves 122f and the tire circumferential direction is θ2. The angle (tilt angle) formed by the narrow grooves 124f and the tire circumferential direction is θ3. The tilt angle θ2 and the tilt angle θ3 are the same angle.

The narrow grooves 120f and sipes 4 have different inclination directions with respect to the tire circumferential direction and the tire lateral direction. This means that the narrow grooves 120f and the slits 4 have different directions extending in the circumferential direction when they extend from the outer side to the inner side in the transverse direction of the vehicle. In addition, the narrow grooves 122f, narrow grooves 124f and sipes 4 have the same direction extending in the circumferential direction of the tire when they extend from the outer side to the inner side in the vehicle transverse direction.

As described above, all of the running portions 31, 32, 33, 34, 35 and 36 are formed with slots 4 and narrow grooves 5. In addition, of the narrow grooves 5, narrow grooves 120a, 120b, 120c, 120d, 120e and 120f in the central zone and the narrow grooves 122a, 122b, 122c, 122d, 122e, 122f, 124a, 124b, 124c, 124d, 124e and 124f in the edge regions have opposite directions extending in the circumferential direction of the tire as they extend from one side to the other side in the transverse direction of the tire (hereinafter also referred to as “having opposite lean directions”). In addition, the sipes 4 and narrow grooves 120a, 120b, 120c, 120d, 120e and 120f in the central region have opposite directions in the tire circumferential direction as they extend from one side to the other side in the tire lateral direction. Additionally, the sipes 4 and narrow grooves 122a, 122b, 122c, 122d, 122e, 122f, 124a, 124b, 124c, 124d, 124e and 124f in the edge regions have the same direction extending in the circumferential direction of the tire when they extend from one side to the other side in the transverse direction of the tire (hereinafter also called “have the same lean direction”).

The tire 1 has a shape having opposite inclination directions of the narrow grooves 5 in the central region and edge regions, opposite inclination directions of the narrow grooves and sipes in the central region, and the same inclination direction of the narrow grooves and sipes in the edge regions. This can improve both braking performance on ice and driving performance on snow. More specifically, making the inclination directions of the slots 4 and narrow grooves 5 in the central regions 110a, 110b, 110c, 110d, 110e and 110f opposite to each other so that the slots 4 and narrow grooves 5 intersect each other allows the edge traction effect to be increased and reduced slipping on ice. In addition, ensuring that the inclination directions of the slots 4 and narrow grooves 5 in the edge areas 112a, 112b, 112c, 112d, 112e, 112f, 114a, 114b, 114c, 114d, 114e and 114f are the same allows snow entering the slots 4 and narrow grooves to be pushed out 5, towards the side of the longitudinal main groove and improve performance on snow.

In the tire 1 according to the present embodiment, sipes 4 and narrow grooves 5 are formed on all of the running portions 31, 32, 33, 34, 35 and 36 and are shaped to satisfy the above-described relationship. This can improve both braking performance on ice and driving performance on snow. Moreover, with respect to the tire 1 according to the present embodiment, in the case where the tread portion is divided in the circumferential direction by lug grooves and therefore has a block shape such as the tread portions 31, 33, 34, 35 and 36, the tire 1 is configured to satisfy the above-described relationship, and therefore to be able to improve both the braking performance on ice and the driving performance on snow. When the sipes 4 and narrow grooves 5 of all the running portions of the running portions 31, 32, 33, 34, 35 and 36 satisfy the above-described relationship, the tire 1 more suitably obtains the above-described effects. However, the formation of at least one middle running section as a specific running section that satisfies the above-described relationship makes it possible to improve both the braking performance on ice and the running performance on snow. Here, the middle running portion is a running portion including running portions located on both sides in the lateral direction of the tire. This means that the middle tread portion is a tread portion in which other tread portions are located on the outer sides of the tread portion in the lateral direction of the tire.

Here, if the widths of the running portions 31, 32, 33, 34, 35, and 36 in the tire lateral direction are 100%, the widths of the central portions 110a, 110b, 110c, 110d, 110e, and 110f are preferably 60% or greater and 80% or greater. less. Likewise, if the widths of the running areas 31, 32, 33, 34, 35 and 36 in the tire lateral direction are 100%, then the widths of the areas 112a, 112b, 112c, 112d, 112e, 112f, 114a, 114b, 114c, 114d, 114e and 114f of the edges are preferably 20% or more and 40% or less. Providing the widths of the center zone and the edge areas of the tread within the range described above allows the edge effect skidding resistance to be increased to improve braking performance on ice and to favorably suppress snow accumulation. This can improve both braking performance on ice and driving performance on snow.

In addition, the inclination angle θa of the sipes 4 with respect to the circumferential direction of the tire (the direction in which the longitudinal main groove extends) is preferably 45° or more and 80° or less, and more preferably is 55° or more and 80° or less. Providing the slot angle within the range described above can suppress plugging while maintaining the edge function of the slots 4.

In addition, the inclination angle θ1 of the narrow grooves 5 with respect to the circumferential direction of the tire (the direction in which the longitudinal main groove extends) in the central region is preferably 40° or more and 65° or less, and more preferably is 45°. Ensuring the angle of the narrow grooves 5 within the range described above can suppress plugging while maintaining the edge function of the narrow groove.

In addition, the inclination angles θ2, θ3 of the narrow grooves 5 with respect to the circumferential direction of the tire (the direction in which the longitudinal main groove extends) in the edge regions are preferably 50° or more and 80° or less, and more preferably 70°. Ensuring the angle of the narrow grooves 5 within the above range can suppress plugging while maintaining the edge function of the narrow groove.

As described above, the narrow grooves 5 preferably have a groove depth of 0.05 mm or more and 1.50 mm or less, a groove width of 0.10 mm or more and 0.80 mm or less, and a spacing (pitch) between the narrow grooves 5 , adjacent to each other, is preferably 0.50 mm or more and 2.00 mm or less. Providing the shape of the narrow grooves 5 within the range described above makes it possible to suppress a decrease in braking performance on ice and driving performance on snow due to a reduction in the contact patch with the ground and a decrease in the rigidity of the block.

Here, the narrow grooves 5 are preferably formed in such a way that the end of the narrow grooves 5 in the central region is preferably connected to the end of the narrow grooves 5 in the edge regions. This means that the narrow grooves 5 are preferably shaped to be connected from one end to the other end of the tread portion in the lateral direction of the tire. By combining the narrow grooves in the central area with the narrow grooves in the edge areas, it is possible to improve the water removal effect, further improve the braking performance on ice and the driving performance on snow, and in particular, further improve the braking performance on ice and the driving performance on snow under high ice temperature conditions .

In FIG. 8 is a plan view illustrating the tread surface of the pneumatic tire 1 according to another embodiment. A plurality (four in FIG. 1) of longitudinal main grooves 21a, 22a, 23a and 24a extending in the circumferential direction of the tire are provided on the tread surface 12a at predetermined intervals in the lateral direction of the tire. In the present embodiment, as illustrated in FIG. 8, the longitudinal main grooves 21a, 22a, 23a and 24a are arranged in this order from the inner side in the vehicle transverse direction to the outer side in the vehicle transverse direction. Further, in the present embodiment, two longitudinal main grooves 21a, 22a are provided on the inner side in the vehicle transverse direction, and two longitudinal main grooves 23a, 24a are provided on the outer side in the vehicle transverse direction. Here, the inner side in the vehicle lateral direction and the outer side in the vehicle lateral direction are indicated as references relative to the lateral direction of the vehicle when the tire 1 is installed on the vehicle. Additionally, two longitudinal main grooves 21a, 24a on the outermost side in the tire lateral direction are defined as shoulder main grooves, and four longitudinal main grooves 22a, 23a on the innermost side in the lateral direction of the tire are defined as center main grooves.

On the tread surface 12a, a plurality (five rows in FIG. 8) of running portions 31a, 32a, 33a, 34a and 35a extending in the circumferential direction of the tire are formed by four longitudinal main grooves 21a, 22a, 23a and 24a. The tread surface 12a according to the present embodiment does not provide a running portion 33 on the tread surface 12.

The tread surface 12a can also obtain the above-described effect by forming sipes 4 and narrow grooves 5 that satisfy the above-described relationship in the running portions 31a, 32a, 33a, 34a and 35a.

Examples

The following gives the performance test results of tires according to the present embodiment as an example. Performance testing of a variety of test tires assessed ice braking performance and snow handling performance. Additionally, for the tires of this example, test tires of size 195/65R15 91Q were mounted on certain rims of size 15×6.5 J and a certain air pressure was applied to the test tires. Also, the test tires were installed on all wheels of the test vehicle - a front-engine, front-wheel drive (FF) vehicle with an engine displacement of 1800 cc. cm. Each tire was filled with air at an air pressure of 250/240 kPa.

For indoor ice braking performance, the test driver conducted a braking test (20 km/h) on an indoor ice skating rink. Further, based on the test results, the estimates were expressed in the form of index values, with the results of a typical example being used as the standard 100. When evaluated, a larger index value indicates a shorter braking distance and better braking performance on ice indoors.

For outdoor ice braking performance, the test driver conducted a braking test (20 km/h) on an icy road. Further, based on the test results, the assessments were expressed in the form of index values, with the results of a typical example being used as the standard 100. When evaluated, a larger index value indicates a shorter braking distance and better braking performance on ice.

In terms of driving performance in snow, the test driver conducted a driving test (10 km/h) on a snow-covered road. Further, based on the test results, the estimates were expressed in the form of index values, with the results of a typical example being used as the standard 100. When evaluated, a higher index value indicates lower fuel consumption while driving, more favorable braking performance while driving and better performance on snow.

The performance evaluation tests were carried out on a tire according to a typical example as an example of a known tire and on a plurality of kinds of pneumatic tires according to the examples. All of these exemplary and example tires were provided with sipes and narrow grooves on the tread surface of the running portion. A typical example of these tires has the same sipes and narrow grooves. Additionally, as a comparative example, a test was also conducted on a tire having opposite sipes and narrow grooves in the shoulder tread portion only.

All of the example tires have oppositely angled sipes and narrow grooves. Further, the example tires are tires differing in the position of the tread portion that satisfies the shown shape, the sipe inclination angle, the inclination angle of the narrow groove, the relationship between the central region and the edge regions on the tread surface of the tread portion, the dimensions of the narrow grooves, and whether the narrow grooves are connected in the central zone and edge area.

The results of performance evaluation tests using these tires are shown in Tables 1-1, 1-2.

It has been found that the tires of the examples can provide improved braking performance on ice and driving performance on snow compared to the exemplary example. This means that the tires of the examples can provide improved braking performance on ice and driving performance on snow accordingly.

Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. For example, in the above-described embodiment, a pneumatic tire was described as an example of a tire, but the invention is not limited to a pneumatic tire, and the embodiment can be naturally applied to a tire that is not filled with air, such as a solid tire. The gas to be filled into the pneumatic tire illustrated in the above-described embodiment may be an inert gas such as nitrogen, argon and helium, in addition to ordinary air or oxygen partial pressure adjusted air.

List of reference items

1, 1a - tire (pneumatic tire)

4, 102 - slot

10 - tread section

12, 12a - tread surface

21, 25 - shoulder main groove (longitudinal main groove)

22, 23, 24 - central main groove (longitudinal main groove)

31, 36 - shoulder running section (running section)

32, 35 - second running section (running section)

33, 34 - central running section (running section)

311, 321, 322, 331, 341, 351 - lug groove

312, 323, 332, 342, 352 - narrow groove

104 - curved section

A1 - central zone

A2 - edge area

AC - line of intersection

VA, BB, BC - block

CL - equatorial plane of the tire

L1 - groove depth

L2 - groove width

L3 - step

R - surface of the contact patch with the ground

T - edge of the contact area with the road surface

Claims (14)

1. Tire containing: on the tread portion there are a plurality of longitudinal main grooves extending in a direction along the circumference of the tire; a plurality of lug grooves extending in a direction intersecting the longitudinal main grooves; and a plurality of running portions formed by the longitudinal main grooves and located in a direction intersecting the longitudinal main grooves; a specific running portion, which is at least one of the running portions, comprising: on the surface of the ground contact patch, a plurality of slots extending in a direction intersecting the longitudinal main grooves and having a line connecting the ends of the slots on the same side in a tire circumferential direction, the line being inclined with respect to the tire circumferential direction and the tire radial direction; and a plurality of narrow grooves extending in a direction intersecting the longitudinal main grooves, inclined with respect to the tire circumferential direction and the tire radial direction, and having a groove depth of 1.50 mm or less; wherein the line of sipes formed on a particular tread is inclined in the same direction as it extends from one side to the other side in the tire width direction, in the central zone in the tire width direction, the line of sipes and narrow grooves have different directions, running at different angles to the tire circumferential direction, in both edge areas on the outer side relative to the central area of the tire, the sipes and narrow grooves have the same direction running along the edge area, in this case, at least one running section is switched on on the outer side in the transverse direction of the tire. 2. The tire according to claim 1, wherein the specific tread portion includes a plurality of blocks formed by longitudinal main grooves and lug grooves. 3. The tire as claimed in claim 1 or 2, wherein the length of a particular tread in the direction intersecting the longitudinal main grooves is taken as 100%, and the length of the central region in the direction intersecting the longitudinal main grooves is 60% or more and 80% or less. 4. Tire according to any one of paragraphs. 1-3, in which the line of sipes has an inclination angle with respect to the tire circumferential direction of 45° or more and 80° or less. 5. Tire according to any one of paragraphs. 1-4, in which the narrow grooves have an inclination angle with respect to the tire circumferential direction in the central region of 40° or more and 65° or less. 6. Tire according to any one of paragraphs. 1-5, in which the narrow grooves have an inclination angle with respect to the circumferential direction of the tire in the edge regions of 50° or more and 80° or less. 7. Tire according to any one of paragraphs. 1 to 6, in which the narrow grooves have a groove depth of 0.05 mm or more and 1.50 mm or less, and a groove width of 0.10 mm or more and 0.80 mm or less, and the distance between the narrow grooves adjacent to each other other is 0.50 mm or more and 2.00 mm or less. 8. Tire according to any one of paragraphs. 1-7, in which the end of the narrow grooves in the central region is connected to the end of the narrow grooves in the edge regions.