JP2007186053A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire superior in on-snow acceleration performance and on-snow braking performance by making distribution of a groove of a tread and a sipe proper. <P>SOLUTION: Total of groove width of lateral grooves of tread shoulder parts 26 at both sides of the tire 10 is made larger than total of groove width of a lateral groove of a tread center part 24. Three-dimensional sipes 40, 42 provided with a bent part in a block depth direction are provided on the tread center part 24 and two-dimensional sipes 44 extending along the block depth direction are provided on the tread shoulder parts 26 at both sides. Total of edge length in a tire width direction of the tread center part 24 is made larger than total of edge length in a tire width direction of the tread shoulder parts 26 at both sides. Thereby, the rigidity of each block of the tread center part 24 is ensured and edge effect is enhanced. Snow pillar shearing force of the lateral groove of the tread shoulder parts 26 at both sides is enhanced, thereby, it is superior in the on-snow acceleration performance and the on-snow braking performance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for use in an automobile traveling on a snowy road, and more particularly to a pneumatic tire having improved snow acceleration performance and snow braking performance.

  Conventionally, when a pneumatic tire for winter travels on a snowy road, there is a difficulty in that the tire slips on the snow surface without being able to grip the snowy road. In order to improve acceleration performance and braking performance at the start of snowy roads, sipes have been designed on the tire tread pattern, but if the sipe is increased to ensure these on-snow performances, the rigidity of the land will decrease. As a result, there is a problem that the handling stability on the paved road cannot be secured. In addition, if the sipe edge is simply increased on the snow, the rigidity of the land portion will decrease, and the small land section that is delimited by the sipe will collapse, reducing the contact area with the road surface. At present, there is a limit to the method of improvement.

However, with respect to this difficulty, the pneumatic tire disclosed in Patent Document 1 improves the edge effect by sipe while ensuring the rigidity of the land portion by appropriately arranging the land portion of the tread and the sipe. , Improve the acceleration and braking performance on snow.
JP 2005-297695 A

By the way, as shown in FIG. 10A, the generation mechanism of μ on the snow (coefficient of friction on snow) is the compression resistance FA that becomes the running resistance on the front surface of the tire, the surface friction force FC on the land surface (tread surface), and the groove (described later). The snow column shearing force FB of the horizontal groove), the edge effect FD of the sipe edge and the land edge (see FIG. 10B for the edge effect).
In addition, since the ground contact shape of the tire generally has a larger contact length in the tread center portion than in the tread shoulder portion, it is possible to increase the edge effect by increasing the edge length in the tire width direction at the tread center portion. Suitable for improving performance on snow. However, if the edge length in the tire width direction is increased, the rigidity of the land portion is lowered, so that the steering stability performance and the wear performance on the paved road surface are deteriorated.

  Moreover, since the tire distribution of Patent Document 1 has a substantially uniform groove distribution and sipe distribution in the tread center portion and the tread shoulder portion, the rigidity of the land portion is improved while improving the edge effect in the tread center portion described above. The problem to be secured has not been solved.

  In the market, it is expected to develop pneumatic tires that have excellent edge acceleration and excellent snow acceleration performance and snow braking performance at the tread center, while ensuring the rigidity of the land.

  An object of the present invention is to provide a pneumatic tire excellent in snow acceleration performance and snow braking performance by optimizing the distribution of tread grooves and sipes in consideration of the above facts.

  In order to achieve the above object, a pneumatic tire according to claim 1 of the present invention is provided with a circumferential groove extending in the tire circumferential direction provided at least one on each side of the tire equatorial surface of the tread surface, and on the tread surface. A plurality of groove widths are arranged in such a manner that the sum of the groove widths is a region between the circumferential grooves on the outermost side in the tire width direction on both sides of the tire equatorial plane. A tread shoulder portion that is a region between them, a large transverse groove extending in the tire width direction, a land portion defined by at least one of the plurality of circumferential grooves and the plurality of transverse grooves, and a tire provided on the land portion. The tread center portion has a sipe having a bent portion in the tire radial direction, and has an edge length in the tire width direction of the land portion and the sipe. Total, being greater in the tread shoulder portion from the tread center portion.

The sum of the edge lengths of the land portion and the sipe in the tire width direction according to claim 1 represents the sum of distances measured in the tire width direction of the respective edges of the land portion and the sipe.
Also, the tread end here refers to a pneumatic tire that is mounted on a standard rim specified in JATMA YEAR BOOK (2005 edition, Japan Automobile Tire Association Standard), and in the size and ply rating applicable to JATMA YEAR BOOK. Fills 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity (internal pressure-load capacity correspondence table) as the internal pressure, and indicates the outermost ground contact portion in the tire width direction when the maximum load capacity is loaded. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

Next, the effect of the pneumatic tire according to claim 1 will be described.
The sum of the edge lengths in the tire width direction of the land part of the tread center part and the sipe of the tread center part is the sum of the edge lengths in the tire width direction of the land part of the tread shoulder part on both sides and the sipe of the tread shoulder part on both sides. By making it larger, the edge effect due to the land portion of the tread center portion and the sipe edge of the tread center portion where the ground contact length of the tire contact shape becomes large is improved.
Further, by providing a bent portion in the tire radial direction of the sipe of the tread center portion, for example, the land portion of the tread center portion is brought into contact with each other when the land portion of the tread center portion is about to fall down during vehicle acceleration or braking. Therefore, it is possible to prevent a decrease in land portion rigidity due to an increase in the edge length of the sipe in the tire width direction at the tread center portion.
Furthermore, by making the total groove width of the lateral grooves of the tread shoulder portions on both sides larger than the total groove width of the lateral grooves of the tread center portion, the tire circumferential length of the land portion becomes longer in the tread center portion. The rigidity in the tire circumferential direction of the land portion is improved, and in the tread shoulder portion, the snow column shear force due to the lateral groove that is insufficient in the tread center portion is improved.

From the above, in the tread center portion, the land portion rigidity is ensured and the edge effect is improved, and in the tread shoulder portion, the snow column shear force is improved.
Therefore, the pneumatic tire of claim 1 is excellent in snow acceleration performance and snow braking performance by optimizing the distribution of tread grooves and sipes.
In addition, the snow column shear force said here is an effect which obtains traction using the shear stress of the snow column formed in the groove part.

  The pneumatic tire according to a second aspect of the present invention is the pneumatic tire according to the first aspect, wherein the sipe of the tread shoulder portion includes a bent portion in a tire radial direction.

Next, the effect of the pneumatic tire of Claim 2 is demonstrated.
Since the sipes provided on the tread shoulders on both sides have bent parts in the tire radial direction, the land area of the tread shoulders on both sides is secured in addition to the land area of the tread center, and the ground contact area Is ensured, and snow acceleration performance and snow braking performance are improved.

  The pneumatic tire according to claim 3 of the present invention is the pneumatic tire according to claim 1 or 2, wherein the sipe of the tread center portion and the sipe of the tread shoulder portion are bent in the tire width direction. It is characterized by providing.

Next, the effect of the pneumatic tire according to claim 3 will be described.
By providing a bend in the tire width direction of the sipe, for example, when a lateral input acts on the tire when turning the vehicle, the bends in the tire width direction of the sipe contact each other and the lateral direction of the land (tire width direction) ) Is suppressed, the lateral land rigidity is ensured, and the land contact area is ensured, so that the on-snow maneuvering performance is improved.

  A pneumatic tire according to a fourth aspect of the present invention is the pneumatic tire according to any one of the first to third aspects, wherein the land width of the tread shoulder portion and the sipe tire width of the tread shoulder portion. LC / LS = 1.05, where LS is the total edge length in the direction and LC is the total edge length in the tire width direction of the land portion of the tread center portion and the sipe of the tread center portion. 2.0 is satisfied.

Next, the effect of the pneumatic tire of Claim 4 is demonstrated.
If LC / LS <1.05, no significant difference can be found between the tread center portion and the tread shoulder portions on both sides, and if LC / LS> 2.0, the land rigidity of the tread center portion is The wear performance of the tread center portion deteriorates extremely. Therefore, the relationship between LC and LS preferably satisfies LC / LS = 1.05 to 2.0.

  A pneumatic tire according to a fifth aspect of the present invention is the pneumatic tire according to any one of the first to fourth aspects, wherein the total groove width of the lateral grooves of the tread shoulder portion is TWS, and the tread center portion. When the total groove width of the horizontal grooves is TWC, TWS / TWC = 1.05 to 5.0 is satisfied.

Next, the effect of the pneumatic tire of Claim 5 is demonstrated.
If TWS / TWC <1.05, no significant difference can be found between the tread center portion and the tread shoulder portions on both sides, and if TWS / TWC> 5.0, the lateral grooves on the tread shoulder portions on both sides can be found. The total groove width becomes extremely large, the tire circumferential length of the land portion of the tread shoulder portion on both sides is shortened, the contact area of the land portion is reduced, the surface friction force is deteriorated, and the entire tire is on the snow. Acceleration performance and braking performance on snow are not improved. Therefore, the relationship between TWS and TWC preferably satisfies TWS / TWC = 1.05-5.0.

  The pneumatic tire according to claim 6 of the present invention is the pneumatic tire according to claim 5, wherein the width of the lateral groove of the tread shoulder portion is wider than the width of the lateral groove of the tread center portion. Features.

Next, the effect of the pneumatic tire of Claim 6 is demonstrated.
By making the groove width of the lateral groove of the tread shoulder part on both sides larger than the groove width of the lateral groove of the tread center part, the tire circumferential direction length of the land part increases and the rigidity of the land part is secured in the tread center part. In the tread shoulder portions on both sides, the snow column shearing force due to the lateral grooves that are insufficient in the tread center portion can be increased, so that snow acceleration performance and snow braking performance are improved.

  The pneumatic tire according to claim 7 of the present invention is the pneumatic tire according to claim 6, wherein the width of the lateral groove of the tread shoulder portion is WS, and the lateral groove of the tread center portion is WC. WS / WC = 1.05-5.0 is satisfied.

Next, the effect of the pneumatic tire of Claim 7 is demonstrated.
If WS / WC <1.05, no significant difference can be found between the tread center portion and the tread shoulder portions on both sides. If WS / WC> 5.0, the lateral grooves on the tread shoulder portions on both sides can be found. The groove width becomes extremely large, the land circumferential direction length of the land part of the tread shoulder part on both sides is shortened, the land contact area of the land part is reduced, the surface friction force is deteriorated, and the acceleration performance on the snow in the whole tire And the braking performance on snow is not improved. Accordingly, the relationship between WS and WC preferably satisfies WS / WC = 1.05 to 5.0.

  The pneumatic tire of the present invention is excellent in snow acceleration performance and snow braking performance by optimizing the distribution of tread grooves and sipes.

[First Embodiment]
Next, a first embodiment of the pneumatic tire of the present invention will be described with reference to FIG. Note that the pneumatic tire 10 of the present embodiment (hereinafter simply referred to as the tire 10) has a tire size of 195 / 65R15, and its internal structure is the same as that of a general radial tire, so that the internal structure is the same. Description of is omitted.

(Circumferential groove)
A tread 12 having a tread surface that comes into contact with the road surface is provided on the outermost layer of the tire 10. In the tread surface of the tread 12 shown in FIG. 1, one center circumferential groove 14 extending substantially along the tire circumferential direction is provided on each side of the tire equatorial plane CL. Further, one shoulder circumferential groove 16 extending substantially in the tire circumferential direction on the outer side in the tire width direction of the center circumferential groove 14 is provided on each side of the tire equatorial plane CL.

In addition, that the center circumferential groove 14 and the shoulder circumferential groove 16 of the present embodiment extend substantially along the tire circumferential direction includes an angle in a range of approximately 0 to 5 degrees with respect to the tire circumferential direction. It is supposed to be. Moreover, although the center circumferential groove 14 and the shoulder circumferential groove 16 of the present embodiment extend substantially along the tire circumferential direction, in other embodiments, they are inclined with respect to the tire circumferential direction ( 5 degrees or more).
Furthermore, the groove width and the groove depth of the center circumferential groove 14 and the shoulder circumferential groove 16 of the present embodiment are the same. However, in other embodiments, the center circumferential groove 14 and the shoulder circumferential groove 16 may not have the same groove width and groove depth.

(Horizontal groove)
The tread 12 is provided with a center lateral groove 18 extending along the tire width direction from one center circumferential groove 14 to the other center circumferential groove 14 and connected to the two center circumferential grooves 14. . Further, a second lateral groove 20 extending from the center circumferential groove 14 to the shoulder circumferential groove 16 while being inclined in the tire width direction (arrow W direction) and connected to the center circumferential groove 14 and the shoulder circumferential groove 16 is provided. . Furthermore, a shoulder lateral groove 22 is provided that extends along the tire width direction from the shoulder circumferential groove 16 to the tread end 12E, and one of the shoulder lateral grooves 22 is connected to the shoulder circumferential groove 16.

  A region between the shoulder circumferential grooves 16 of the tread 12 is referred to as a tread center portion 24, and a region between the shoulder circumferential grooves 16 and the tread end 12E is referred to as a tread shoulder portion 26.

  Further, the shoulder lateral grooves 22 included in the tread shoulder portions 26 on both sides are wider than both the center lateral grooves 18 and the second lateral grooves 20 included in the tread center portion 24, and the total groove widths of the tread shoulder portions 26 on both sides are included. Is larger than the sum of the groove widths of the tread center portion 24 (the sum of the groove widths of the center lateral groove and the second lateral groove).

In the present embodiment, the center lateral groove 18 and the shoulder lateral groove 22 extend along the tire width direction, and the second lateral groove 20 extends while inclining in the tire width direction. However, in other embodiments, the center lateral groove 18 and the shoulder lateral groove 22 are extended. May extend while inclining in the tire width direction, and the second lateral groove 20 may extend in the tire width direction.
The circumferential groove may extend in a zigzag shape (or wave shape) in the tire circumferential direction, and the lateral groove may extend in a zigzag shape (or wave shape) in the tire width direction. The width refers to the average value of the groove width.

  Moreover, although the groove width of the center lateral groove 18 and the second lateral groove 20 of this embodiment is the same, in other embodiment, the groove width of the center lateral groove 18 and the second lateral groove 20 may not be the same. To do.

(Block, Sipe)
A block-shaped center block 30 is defined on the tread 12 by a center circumferential groove 14 and a center lateral groove 18. A three-dimensional sipe 40 is provided on the tread surface portion 30 </ b> S of the center block 30 in parallel with the center lateral groove 18. The three-dimensional sipe 40 includes a bent portion in the block depth direction (inner direction in the tire radial direction (arrow D direction)). Specifically, as shown in FIG. 6, the three-dimensional sipe 40 includes a straight portion 40A extending from the tread surface portion 30S of the center block 30 along the block depth direction, and from the end of the straight portion 40A to the block depth direction. A bending portion 40B that swings and a linear portion 40C that extends further in the block depth direction from the end of the bending portion 40B are provided. In the three-dimensional sipe 40, the center block 30 is divided in the tire circumferential direction to form a plurality of small blocks 30M.

  A block-shaped second block 32 is defined on the tread 12 by a center circumferential groove 14, a shoulder circumferential groove 16, and a second lateral groove 20. A three-dimensional sipe 42 is provided on the tread surface portion 32S of the second block 32 in parallel with the second lateral groove 20. The three-dimensional sipe 42 has the same shape as the three-dimensional sipe 40 described above, and includes a straight portion 42A, a bent portion 42B, and a straight portion 42C. In the three-dimensional sipe 42, the second block 32 is divided in the tire circumferential direction to form a plurality of small blocks 32M.

  Further, a block-shaped shoulder block 34 is defined by a shoulder circumferential groove 16, a tread end 12 </ b> E and a shoulder lateral groove 22 on the tread 12. A two-dimensional sipe 44 is provided on the tread surface portion 34 </ b> S of the shoulder block 34 in parallel with the shoulder lateral groove 22. The two-dimensional sipe 44 extends along the block depth direction. Specifically, as shown in FIG. 3, the two-dimensional sipe 44 includes a straight portion 44 </ b> A that extends from the tread surface portion 34 </ b> S of the shoulder block 34 along the block depth direction. In the two-dimensional sipe 44, the shoulder block 34 is divided in the tire circumferential direction to form a plurality of small blocks 34M.

In addition, each sipe of this embodiment is configured to be arranged so as to be parallel to the transverse groove that defines the block in which the sipe is provided, but in other embodiments, the transverse groove and the sipe are parallel to each other. It is not necessary.
In addition, each sipe of the present embodiment is configured to divide each block in the tire circumferential direction to form a plurality of small blocks, but in other embodiments, one of the sipe is open to a groove. The structure may be sufficient, and the structure provided only in the inside of a block without opening in a groove | channel may be sufficient.
In addition, each sipe of the present embodiment extends along the block depth direction, but in other embodiments, the sipe does not extend along the block depth direction but extends in an inclined manner in the block depth direction. It may be acceptable.

The depths of the three-dimensional sipes 40 and 42 and the two-dimensional sipes 44 of the present embodiment are uniformly 6.6 mm when new, but may be other than 6.6 mm in other embodiments. The depth may be different depending on the installation position of each sipe.
Further, the groove depths of the circumferential grooves and the lateral grooves of the present embodiment are each uniformly 10 mm when new, but may be other than 10 mm in other embodiments. The groove depth may be different depending on the groove position.

  From the sum of the edge lengths in the tire width direction of the shoulder block 34 and the two-dimensional sipe 44 of the tread shoulder portion 26 on both sides, the tire block direction of the center block 30, the second block 32, and the three-dimensional sipes 40 and 42 of the tread center portion 24. When the total edge length in the tire width direction of the tread shoulder portions 26 on both sides is LS, and the total edge length in the tire width direction of the tread center portion 24 is LC, It is preferable to satisfy LC / LS = 1.05 to 2.0.

Further, TWS / TWC = 1.05, where TWS is the total width of the shoulder lateral grooves 22 of the tread shoulder portions 26 on both sides and TWC is the total width of the center lateral grooves 18 and the second lateral grooves 20 of the tread center portion 24. It is preferable to satisfy -5.0.
Further, when the width of the shoulder lateral groove 22 of the tread shoulder portion 26 on both sides is WS and the width of the center lateral groove 18 (or the second lateral groove 20) of the tread center portion 24 is WC, WS / WC = 1.05-5. 0.0 is preferably satisfied.

(Function)
Next, the operation of the first embodiment will be described.
As shown in FIG. 1, the sum of the edge lengths in the tire width direction of the center block 30, the second block 32, and the three-dimensional sipes 40 and 42 of the tread center portion 24 is calculated as the shoulder blocks 34 and 2 of the tread shoulder portion 26 on both sides. By making the dimension sipe 44 larger than the sum of the edge lengths in the tire width direction, the edge effect by the edge of the block and sipe in the tread center portion 24 where the contact length of the tire contact shape becomes large as shown in FIG. 2 is improved. To do.

  Further, by providing the three-dimensional sipe 40 having the bent portion 40B in the block depth direction in the center block 30 of the tread center portion 24, for example, the small block 30M of the center block 30 tries to collapse during vehicle acceleration or braking. Since the bent portions 40B of the three-dimensional sipe 40 come into contact with each other to suppress this, the block rigidity (land portion rigidity) of the center block 30 can be secured. Similarly, the block rigidity of the second block 32 can be ensured by providing the second block 32 of the tread center portion 24 with the three-dimensional sipe 42 having the bent portion 42B in the block depth direction. Therefore, it is possible to prevent the block rigidity from being lowered due to an increase in the edge length in the tire width direction of the blocks and sipes in the tread center portion 24.

  Further, the tread center portion 24 is configured such that the total width of the lateral grooves of the shoulder lateral grooves 22 of the tread shoulder portions 26 on both sides is larger than the total width of the center lateral grooves 18 and the second lateral grooves 20 of the tread center portion 24. The tire circumferential length of each block is increased, the rigidity of the block in the tire circumferential direction is improved, and the snow column shearing force by the shoulder lateral grooves 22 is improved in the tread shoulder portions 26 on both sides.

  From the above, in the tread center portion 24, the block rigidity is secured and the edge effect by each edge is improved, and in the tread shoulder portion 26, the snow column shear force is improved. Therefore, the tire 10 is excellent in snow acceleration performance and snow braking performance by optimizing the distribution of the grooves and sipes of the tread 12.

  Further, by making the width of the shoulder lateral groove 22 of the tread shoulder portion 26 on both sides larger than the width of the center lateral groove 18 and the second lateral groove 20 of the tread center portion 24, the tread center portion 24 has a tire circumference of each block. The direction length is increased and the block rigidity in the tire circumferential direction is secured, and the snow column shearing force by the shoulder lateral grooves 22 can be increased in the tread shoulder portions 26 on both sides, so that the acceleration performance on snow and the braking performance on snow are improved. To do.

  If LC / LS <1.05, no significant difference can be found between the tread center portion 24 and the tread shoulder portions 26 on both sides. If LC / LS> 2.0, the tread center portion 24 As a result, the block rigidity of the tread center portion 24 is extremely lowered, and the wear performance of the tread center portion 24 is deteriorated. Therefore, the relationship between LC and LS preferably satisfies LC / LS = 1.05 to 2.0.

  If TWS / TWC <1.05, no significant difference can be found between the tread center portion 24 and the tread shoulder portions 26 on both sides, and if TWS / TWC> 5.0, the shoulder of the tread shoulder portion 26. The total groove width of the lateral grooves 22 becomes extremely large, the tire circumferential direction length of the shoulder block 34 of the tread shoulder portion 26 on both sides is shortened, the contact area is reduced, the surface friction force is deteriorated, and the entire tire is reduced. Acceleration performance on snow and braking performance on snow will not improve. Therefore, the relationship between TWS and TWC preferably satisfies TWS / TWC = 1.05-5.0.

  If WS / WC <1.05, no significant difference can be found between the tread center portion 24 and the tread shoulder portions 26 on both sides, and if WS / WC> 5.0, the tread shoulder portions 26 on both sides. The width of the shoulder lateral groove 22 is extremely large, the length of the shoulder block 34 of the tread shoulder portion 26 on both sides in the tire circumferential direction is shortened, the ground contact area is reduced, and the surface friction force is deteriorated. Acceleration performance on snow and braking performance on snow will not improve. Therefore, the relationship between WS and WC preferably satisfies WS / WC = 1.0 to 5.0.

  Further, since the second block 32 and the three-dimensional sipe 42 are inclined in the tire width direction, the edge effect on the lateral external force is also improved on the tire contact surface.

[Second Embodiment]
Next, a second embodiment of the pneumatic tire of the present invention will be described. In the description of the tire 10, only the configuration different from that of the first embodiment will be described. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

As shown in FIG. 7, a three-dimensional sipe 50 is provided on the tread surface portion 30 </ b> S of the center block 30 instead of the three-dimensional sipe 40 of the first embodiment. The three-dimensional sipe 50 extends in the tire width direction parallel to the center lateral groove 18 and includes a bent portion in the tire width direction, and extends in the block depth direction and includes a bent portion in the block depth direction. Specifically, the three-dimensional sipe 50 includes a straight portion 50A extending from one center circumferential groove 14 in parallel with the center lateral groove 18, a bent portion 50B extending in a sinusoidal shape from the end of the straight portion 50A, and a bent portion. A straight portion 50C extending in parallel with the center lateral groove 18 from the terminal end of 50B to the other center circumferential groove 14 is provided.
Further, the straight portions 50A and 50C of the three-dimensional sipe 50 extend from the tread surface portion 30S along the block depth direction, and the bent portion 50B extends from the tread surface portion 30S to the sine wave shape in the block depth direction.

  Also, the second block 32 is provided with a three-dimensional sipe 52 having the same shape as the above-described three-dimensional sipe 50 instead of the three-dimensional sipe 42 of the first embodiment. The three-dimensional sipe 52 includes a straight portion 52A, a bent portion 52B, and a straight portion 52C.

(Function)
Next, the operation of the second embodiment will be described. In addition, it is the same structure as 1st Embodiment, The description of the effect | action of the part which abbreviate | omitted description in 2nd Embodiment shall be abbreviate | omitted.
By providing the three-dimensional sipe 50 with a bent portion 50B that bends in the tire width direction and the block depth direction, when a lateral input acts on the tire during vehicle turning, the bent portions 50B of the three-dimensional sipe 50 contact each other. Thus, the center block 30 is prevented from falling in the lateral direction (tire width direction), the lateral block rigidity is ensured, and the ground contact area of the center block 30 is also ensured.
Similarly, the three-dimensional sipe 52 suppresses the falling of the second block 32 in the lateral direction (tire width direction), the lateral block rigidity is ensured, and the contact area of the second block 32 is also ensured. Therefore, the on-snow handling stability performance of the tread center portion 24 is improved.
In addition, although the bending parts 50B and 52B of this embodiment are made into the sine wave shape, in other embodiment, it shall be a wave shape or a zigzag shape.

[Third Embodiment]
Next, a third embodiment of the pneumatic tire of the present invention will be described. In addition, description of the tire 10 of this embodiment demonstrates only a structure different from 1st and 2nd embodiment. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.
The tread portion 34S of the shoulder block 34 is provided with the three-dimensional sipe 40 of the first embodiment instead of the two-dimensional sipe 44 of the first embodiment.

(Function)
Next, the operation of the third embodiment will be described. In addition, it is the same structure as 1st Embodiment, The description of the effect | action of the part which abbreviate | omitted description in 3rd Embodiment shall be abbreviate | omitted.
Since the three-dimensional sipe 40 is provided in the shoulder block 34 of the tread shoulder portion 26 on both sides, the block rigidity of the shoulder block 34 of the tread shoulder portion 26 on both sides is secured in addition to the respective blocks of the tread center portion 24. The ground contact area of the block 34 is ensured, and snow acceleration performance and snow braking performance are improved.
In this embodiment, the three-dimensional sipe 40 is provided instead of the two-dimensional sipe 44. However, in other embodiments, a three-dimensional sipe 42 may be provided.

(Other embodiments)
In the first to third embodiments, the sipes are configured as three-dimensional sipes 40 (see FIG. 6), 50 (see FIG. 7) and two-dimensional sipes 44 (see FIG. 3). Thus, when viewed from the tire width direction, it extends linearly from the block tread surface in the block depth direction (linear portion 70A), inclines (bent portion 70B), and extends linearly in the block depth direction (linear portion 70C). The three-dimensional sipe 70 having a generally crank shape may be used.

  Further, as shown in FIG. 5, when viewed from the tire width direction, it extends linearly from the block tread surface in the block depth direction (straight portion 80A), inclines and then extends linearly in the block depth direction. The configuration may include a three-dimensional sipe 80 that is inclined in the opposite direction (bent portion 80B) and linearly extends in the block depth direction (linear portion 80C).

  Further, as shown in FIG. 8A, a three-dimensional sipe 60 that extends in a zigzag shape in the tire width direction and the block depth direction may be used. (Protrusions 60A and recesses 60B (hatched portions)) are alternately arranged. FIG. 8B is a front view of the three-dimensional sipe 60 (a view of one side of the three-dimensional sipe 60 viewed from the front), and a C line (broken line) in the drawing indicates a contour line.

  Further, as shown in FIG. 9, the front view of the sipe as viewed from the front has a configuration like a three-dimensional sipe 90 in which substantially cubic irregularities (protrusions 90 </ b> A and recesses 90 </ b> B) are alternately arranged. Also good.

  In the first to third embodiments, the center block 30 and the second block 32 that are partitioned and formed in the tread center portion 24 in the block shape are arranged. The center rib and the second rib that extend continuously in the tire circumferential direction without being divided by the respective lateral grooves may be used. At this time, by arranging the three-dimensional sipes at high density on the center rib and the second rib, the edge effect of the three-dimensional sipes can be improved, and the block rigidity at the tread center portion 24 is ensured.

(Test example)
In order to confirm the performance improvement effect of the pneumatic tire of the present invention, two types of pneumatic tires of the example of the present invention and one type of pneumatic tire of the comparative example are prepared and mounted on a passenger car on the snow. Acceleration performance test and braking performance test were conducted. The sizes of the tires used in the tests were 195 / 65R15, and the tires were assembled to the rim 6J-15, and the inner pressure was set to 200 kpa and mounted on the passenger car.

The acceleration performance test was evaluated by measuring the time (acceleration time) from the stationary state until the accelerator was fully opened and traveling 50 m.
The braking performance test was evaluated by measuring the braking distance when the full brake was applied from 30 km / h.
In each case, the evaluation results of the two types of tests are shown in Table 1 as an index display when the numerical value of the tire of the comparative example is 100. In addition, an evaluation numerical value shows a favorable result, so that it is large.

Example 1: A tire according to the first embodiment.
Example 2: A tire according to the second embodiment.
Comparative example: A tire having a tread pattern shown in FIG. The tread 102 of the tire 100 of this comparative example includes a circumferential groove 104 that is provided two symmetrically with respect to the tire equatorial plane CL, and a lateral groove 106 that is connected to the circumferential groove 104. A sipe 110 is provided on the tread portion of the block 108 that is partitioned between the lateral grooves 106. At this time, the edge length in the tire width direction of the tread center portion 24 and the tread shoulder portion 26 and the groove width of the lateral groove are equal, and the configuration of the sipe 110 is the same as the two-dimensional sipe 44 (see FIG. 3) of the first embodiment. It is the same composition.
In addition, the groove | channel (circumferential groove | channel 104 and the lateral groove | channel 106) depth of the tire of a comparative example is 10 mm similarly to the tire of Example 1, and the depth of the sipe is 6.6 mm similarly to the tire of Example 1.

  From the results in Table 1, it can be seen that the tires of Examples 1 and 2 have better acceleration performance and braking performance on snow than the tires of Comparative Examples by optimizing the tread sipe and groove arrangement. .

It is a top view showing a tread pattern of a pneumatic tire concerning a 1st embodiment. FIG. 2 is a plan view showing a tire ground contact shape when the tire of FIG. 1 goes straight. It is a perspective view which shows the shoulder block of the pneumatic tire which concerns on 1st Embodiment. It is a perspective view which shows the center block of the pneumatic tire which concerns on other embodiment. It is a perspective view which shows the center block of the pneumatic tire which concerns on other embodiment. It is a perspective view which shows the center block of the pneumatic tire which concerns on 1st Embodiment. It is a perspective view which shows the center block of the pneumatic tire which concerns on 2nd Embodiment. (A) It is a perspective view which shows the center block of the pneumatic tire which concerns on other embodiment. (B) It is the front view which looked at the surface of the one side of the sipe provided in the center block from the front. It is the front view which looked at the surface of the one side of the sipe provided in the center block of the pneumatic tire which concerns on other embodiment from the front. (A) It is the figure which represented the generation | occurrence | production mechanism of the traction on the snow of a pneumatic tire, and a brake seeing from the tire width direction. (B) It is an enlarged view showing the generation | occurrence | production mechanism of the edge effect by the sipe edge of FIG. 10 (A). It is a top view which shows the tread pattern of the pneumatic tire of a comparative example.

Explanation of symbols

10 Pneumatic tire 12 Tread 12E Tread end 14 Center circumferential groove (circumferential groove)
16 Shoulder circumferential groove (circumferential groove)
18 Center lateral groove (horizontal groove)
20 Second horizontal groove (horizontal groove)
22 Shoulder lateral groove (lateral groove)
24 tread center 26 tread shoulder 30 center block (land)
32 Second Block (Land)
34 Shoulder block (Land)
40 3D Sipe (Sipe)
42 3D Sipe (Sipe)
44 2D Sipe (Sipe)
50 3D sipe
52 3D Sipe (Sipe)
60 3D Sipe (Sipe)
70 3D Sipe (Sipe)
80 3D Sipe (Sipe)
90 3D Sipe (Sipe)
CL tire equator

Claims (7)

One or more circumferential grooves extending in the tire circumferential direction on both sides of the tire equator surface of the tread surface;
A plurality of the tread treads, and the total groove width is the outermost circumferential groove in the tire width direction from the tread center portion which is a region between the circumferential grooves on the outermost tire width direction on both sides of the tire equatorial plane. A lateral groove extending in the large tire width direction at the tread shoulder portion which is a region between the tire and the tread end,
A land portion defined by at least one of the plurality of circumferential grooves and the plurality of lateral grooves;
A sipe provided in the land portion, extending in a tire width direction and a tire radial direction, and having a bent portion in the tire radial direction in the tread center portion;
A pneumatic tire characterized in that a sum of edge lengths in the tire width direction of the land portion and the sipe is larger in the tread center portion than in the tread shoulder portion.   The pneumatic tire according to claim 1, wherein the sipe of the tread shoulder portion includes a bent portion in a tire radial direction.   The pneumatic tire according to claim 1 or 2, wherein the sipe of the tread center portion and the sipe of the tread shoulder portion include a bent portion in a tire width direction.   The sum of the edge lengths in the tire width direction of the sipe of the land portion and the tread shoulder portion of the tread shoulder portion is LS, and the land portion of the tread center portion and the sipe of the sipe of the tread center portion are in the tire width direction. 4. The pneumatic tire according to claim 1, wherein LC / LS = 1.05 to 2.0 is satisfied when a sum of edge lengths is LC. 5.   When the total groove width of the lateral grooves of the tread shoulder portion is TWS and the total groove width of the lateral grooves of the tread center portion is TWC, TWS / TWC = 1.05 to 5.0 is satisfied. The pneumatic tire according to any one of claims 1 to 4.   The pneumatic tire according to claim 5, wherein a groove width of the horizontal groove of the tread shoulder portion is wider than a groove width of the horizontal groove of the tread center portion.   The width of the horizontal groove of the tread shoulder portion is WS, and when the horizontal groove of the tread center portion is WC, WS / WC = 1.05 to 5.0 is satisfied. Pneumatic tire.

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