JP2008062841A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire formed to improve moving performance on a dry road surface while improving moving performance on a snowy road surface. <P>SOLUTION: A tread 1 is provided with a first main groove 3, a second main groove 2a and a third main groove 2b in the circumferential direction of the tire, and a wide first land part 4a and a narrow second land part 4b are formed at a center region of the tread. Lug grooves 7a extending into the first land part 4a from a shoulder end 5a on the inside of a vehicle are terminated in the first land part 4a, and a plurality of inclined auxiliary grooves 8 communicating with at least three lug grooves 7a are provided in the first land part 4a. The first land part 4a is formed into a block row 4x on the inside of the vehicle, and a rib row 4y on the outside of the vehicle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that simultaneously improves exercise performance on a snowy road surface and exercise performance on a dry road surface.

  In general, a pneumatic tire for icy and snowy roads employs a block pattern as a tread pattern to increase the groove depth or groove area, as illustrated in FIG. 5, in order to ensure motion performance on a snowy road surface. Has been generally set (see, for example, Patent Document 1). However, in the tire having such a wide groove area, the surface area of the block (land portion) becomes small as a whole pattern, and there is a problem that the driving stability on the dry road surface is inferior.

As described above, it is very difficult to simultaneously achieve the motion performance on the road surface on snow and the motion performance on the dry road surface. In order to solve this problem, many proposals have been made so far, but all have advantages and disadvantages, and there is still room for improvement.
JP 2004-25954 A

  An object of the present invention is to solve such a conventional problem, and to provide a pneumatic tire that improves the exercise performance on a dry road surface while improving the exercise performance on a snowy road surface.

In order to achieve the above object, the pneumatic tire of the present invention is a pneumatic tire in which left and right tread patterns in which a mounting position with respect to a vehicle is designated are formed asymmetrically.
In the tread surface, a first main groove extending in the tire circumferential direction in a central region shifted from the tire equator line to the vehicle outer side, a second main groove extending in the tire circumferential direction in a shoulder region inside the vehicle, and a shoulder region outside the vehicle A third main groove extending in the tire circumferential direction is provided, and a first land portion partitioned into the first main groove and the second main groove is divided into the first main groove and the third main groove. The tire width is wider than the two land portions, and the tire width is divided into a first shoulder land portion partitioned from the second main groove to the vehicle inner side and a second shoulder land portion partitioned from the third main groove to the vehicle outer side. Forming a plurality of lug grooves extending in the direction, terminating the lug grooves of the first shoulder land portion in the first land portion beyond the second main groove, and at least three or more in the first land portion By providing multiple inclined sub-grooves that communicate with the lug grooves , Characterized in that the formation of the first land portion in a rib row of the block row and the vehicle outer side of the vehicle interior.

  It is preferable that the pneumatic tire of the present invention further includes the configurations described in (1) to (7) below in the configuration described above.

(1) The inclined sub-groove is constituted by a straight groove having a different inclination direction from the lug groove and having one end opened in the lug groove and the other end terminated in the first land portion. In this case, the intersection angle α on the acute angle side with respect to the tire circumferential direction of the inclined sub-groove may be set to 10 to 40 °.

(2) A plurality of inclined grooves extending from the first main groove and terminating in the second land portion and inclined rearward in the tire rotation direction are formed in the second land portion.

(3) The width of the first land portion is set to 15 to 40% of the tire ground contact width.
(4) The width of the second land portion is set to 8 to 20% of the tire ground contact width.

(5) The total width of the first main groove, the second main groove, and the third main groove is set to 15 to 35% of the tire ground contact width.

(6) A fourth main groove extending in the tire circumferential direction is provided between the first main groove and the third main groove.
(7) A large number of sipes extending in the tire width direction are formed on the tread surface.

  According to the pneumatic tire of the present invention, three main grooves extending in the tire circumferential direction are provided on the tread surface, and the wide first land portion and the narrow second land portion are formed in the tread central region. The lug groove extending from the inside of the vehicle into the first land portion is terminated in the first land portion, and a plurality of inclined subgrooves communicating with at least three or more lug grooves are provided in the first land portion. Since the land portion is formed in the block row on the vehicle inner side and the rib row on the vehicle outer side, the maneuvering on the snowy road surface is mainly performed by the edge effect of the lug groove and the inclined sub groove that divides the block row on the vehicle inner side in the first land portion. While improving stability and turning performance, the rigidity of the tread central region is ensured by the rib row outside the vehicle in the first land portion, and the steering stability on the dry road surface can be improved.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a partial plan view showing a tread surface of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 is a partial plan view corresponding to FIG. 1 for explaining the configuration of the tread surface.

  In FIG. 1, a tread surface 1 includes a first main groove 3 extending in the tire circumferential direction in a central region shifted from the tire equator line CL to the vehicle outer side (right side in the drawing), and a shoulder region on the vehicle inner side (left side in the drawing). Are provided with a second main groove 2a extending in the tire circumferential direction and a third main groove 2b extending in the tire circumferential direction in a shoulder area outside the vehicle, respectively, and partitioned into a first main groove 3 and a second main groove 2a. The first land portion 4a is formed wider than the second land portion 4b partitioned into the first main groove 3 and the third main groove 2b.

  Further, a plurality of first shoulder land portions 6a partitioned from the second main groove 2a on the vehicle inner side and second shoulder land portions 6b partitioned on the vehicle outer side from the third main groove 2b respectively extend in the tire width direction. Lug grooves 7a and 7b are formed, and the lug groove 7a of the first shoulder land portion 6a terminates in the first land portion 4a beyond the second main groove 2a, and at least 3 in the first land portion 4a. A plurality of inclined sub-grooves 8 communicating with at least three (three in the figure) lug grooves 7a are provided, and the first land portion 4a is formed in the block row 4x on the vehicle inner side and the rib row 4y on the vehicle outer side. Has been.

  This improves the steering stability and turning performance on the road surface on snow mainly by the edge effect of the lug grooves 7a and the inclined sub-grooves 8 that partition the block row 4x on the vehicle inner side in the first land portion 4a. The rib row 4y on the vehicle outer side in the portion 4a ensures the rigidity of the tread central region, and the steering stability on the dry road surface can be improved.

  In the embodiment of FIG. 1, the lug groove 7a and the inclined sub-groove 8 in the first land portion 4a are connected at the terminal position of the lug groove 7a, but the inclined sub-groove 8 is an intermediate position of the lug groove 7a. And can be formed so as to be connected to the lug groove 7a.

  In the present invention, the lug groove 7a extending from the shoulder end 5a inside the vehicle into the first land portion 4a is preferably inclined rearward in the tire rotation direction R in the first land portion 4a as shown in FIG. It is formed. And it is good to comprise the inclination subgroove 8 mentioned above by the straight groove which makes the inclination direction different from the lug groove 7a, opens one end to the lug groove 7a, and terminates the other end in the 1st land part 4a. Thereby, the steering stability and turning performance on the road surface on snow can be improved reliably.

  In this case, the intersection angle α (see FIG. 2) on the acute angle side with respect to the tire circumferential direction of the inclined sub-groove 8 may be set to 10 to 40 °, preferably 15 to 25 °. If the crossing angle α is less than 10 °, the turning performance on the road surface on snow is degraded, and if it exceeds 40 °, a difference in rigidity occurs between the blocks formed on the second main groove 2a side of the first land portion 4a, resulting in wear resistance. Decreases. Note that the above-described crossing angle α is an angle formed by the widthwise center line of the inclined sub-groove 8 and the tire circumferential direction.

  Furthermore, a plurality of inclined grooves 9 extending from the first main groove 3 and terminating in the second land part 4b and inclined rearward in the tire rotation direction may be formed in the second land part 4b described above. Thereby, the running performance on a snowy road surface can be further improved. In this case, if the tip of the inclined groove 8 is extended to the third main groove 2b and the second land portion 4b is formed in a block row, the rigidity in the tread central region is insufficient and the handling stability on the dry road surface is improved. The effect will be reduced.

In the pneumatic tire of the present invention, the width X of the first land portion 4a is set to 15 to 40 of the tire ground contact width W.
%, Preferably 20-30%. Thereby, the rigidity of the land part in the 1st land part 4a can be ensured appropriately, and the steering stability in the dry road surface can be improved reliably. If the width X of the first land portion 4a is less than 15% of the tire ground contact width W, the rigidity of the land portion is insufficient and the running performance on the dry road surface is deteriorated, and if it exceeds 40%, the distance between the adjacent land portions 6a and 4b. The rigidity difference becomes too large and the wear resistance decreases.

  Furthermore, the width Y of the second land portion 4b may be set to 8 to 20%, preferably 10 to 15% of the tire ground contact width W. Thereby, the rigidity in the tread central region can be ensured and the steering stability on the dry road surface can be reliably improved. If the width Y of the second land portion 4b deviates from the above-described range, the difference in rigidity from the adjacent other land portions 4a and 6b becomes too large and the wear resistance is lowered.

  In the present invention, the tire contact width W refers to the contact width of the tire in a state where the tire is filled with air pressure specified by JATMA and a load corresponding to 80% of the maximum load specified by JATMA is applied.

  In the present invention, the total width of the first main groove 3, the second main groove 2a, and the third main groove 2b formed on the tread surface 1 is 15 to 35%, preferably 20 to 25% of the tire ground contact width W. It is good to adjust as follows. If the total width is less than 15% of the tire ground contact width W, the wet performance on the road surface on snow will be reduced, and if it exceeds 35%, the handling stability on the dry road surface will be reduced.

  In the embodiment of FIG. 1, the case where the main groove formed in the tread surface 1 extending in the tire circumferential direction includes the first main groove 3, the second main groove 2 a, and the third main groove 2 b is shown. In the case of a flat tire having a surface, as shown in FIG. 3, a fourth main groove 10 extending in the tire circumferential direction may be formed in the center region in the tire width direction of the second land portion 4 b. In this case, the width of the circumferential groove 10 is not particularly limited. The width Y of the second land portion 4b and the total width of the first main groove 3, the second main groove 2a, and the third main groove 2b described above. The rule regarding is applied as it is regardless of the presence or absence of the fourth main groove 10.

  In order to ensure the running performance on the road surface on snow, the tread surface 1 in the pneumatic tire of the present invention is generally formed with a large number of sipes extending generally in the tire width direction as shown in FIG. The plane form of the sipe is not particularly limited, and may be a wavy form or a zigzag form.

  A conventional tire having a tread pattern of FIG. 5 and a tire of the present invention having a tread pattern of FIG. 4 were manufactured with a tire size of 205 / 55R16.

  These two types of tires are assembled on a 6.5J rim, filled with 200 kPa of internal pressure, and mounted on the front and rear wheels of a 2000cc rear wheel drive vehicle. The results were evaluated in terms of steering stability on a dry road surface, and the results are shown in Table 1 using an index with the conventional tire as 100. The larger the value, the better.

[Steering stability on snowy road surface]
A test course consisting of a flat snowy road surface was run at an average speed of 60 km / h, and a comprehensive test was carried out by a skilled test driver with a feeling mainly based on race change characteristics and cornering characteristics.

[Swivel on snowy road surface]
A 15 m radius circular turning course consisting of a flat on-snow road surface was run at an average speed of 30 km / h, and evaluation by feeling was carried out by a skilled test driver.

[Operation stability on dry road surface]
A test course consisting of an asphalt road surface was run at an average speed of 120 km / h, and a comprehensive evaluation was conducted by a skilled test driver with a feeling that mainly consisted of race change characteristics and cornering characteristics.

  As a result, it can be seen that the tire of the present invention further improves the handling stability on the dry road surface while improving the handling stability and turning performance on the snowy road surface as compared with the conventional tire.

It is a partial top view which shows the tread surface of the pneumatic tire which consists of embodiment of this invention. It is a partial top view equivalent to FIG. 1 for demonstrating the structure of the tread surface of FIG. It is a partial top view which shows the tread surface of the pneumatic tire which consists of other embodiment of this invention. It is a partial top view which shows the tread surface of this invention tire employ | adopted in the Example. It is a partial top view which shows the tread surface of the conventional tire employ | adopted in the Example.

Explanation of symbols

1 tread surface 2a second main groove 2b third main groove 3 first main groove 4a first land portion 4b second land portion 4x block row 4y rib row 5a, 5b shoulder end 6a first shoulder land portion 6b second shoulder land Part 7a, 7b Lug groove 8 Inclined sub groove 9 Inclined groove 10 Fourth main groove CL Tire equatorial line R Tire rotation direction

Claims (9)

In a pneumatic tire having an asymmetric tread pattern in which a mounting position with respect to a vehicle is specified,
In the tread surface, a first main groove extending in the tire circumferential direction in a central region shifted from the tire equator line to the vehicle outer side, a second main groove extending in the tire circumferential direction in a shoulder region inside the vehicle, and a shoulder region outside the vehicle A third main groove extending in the tire circumferential direction is provided, and a first land portion partitioned into the first main groove and the second main groove is divided into the first main groove and the third main groove. While forming wider than 2 land,
A plurality of lug grooves extending in the tire width direction are formed in the first shoulder land portion partitioned from the second main groove on the vehicle inner side and the second shoulder land portion partitioned from the third main groove on the vehicle outer side, respectively. And
A plurality of inclined sub-channels that terminate the lug groove of the first shoulder land portion in the first land portion beyond the second main groove and communicate with at least three lug grooves in the first land portion. A pneumatic tire in which the first land portion is formed in a block row inside the vehicle and a rib row outside the vehicle by providing a groove.   2. The pneumatic tire according to claim 1, wherein the inclined sub-groove is configured as a straight groove having a different inclination direction from the lug groove and having one end opened in the lug groove and the other end terminated in the first land portion. .   The pneumatic tire according to claim 2, wherein an intersection angle α on an acute angle side with respect to the tire circumferential direction of the inclined sub-groove is 10 to 40 °.   The pneumatic according to claim 1, 2, or 3, wherein a plurality of inclined grooves extending from the first main groove and ending in the second land part and inclined rearward in the tire rotation direction are formed in the second land part. tire.   The pneumatic tire according to claim 1, 2, 3, or 4, wherein the width of the first land portion is 15 to 40% of a tire ground contact width.   The pneumatic tire according to claim 1, 2, 3, 4, or 5, wherein a width of the second land portion is 8 to 20% of a tire ground contact width.   The pneumatic tire according to claim 1, 2, 3, 4, 5, or 6, wherein a total width of the first main groove, the second main groove, and the third main groove is 15 to 35% of a tire ground contact width.   The pneumatic tire according to claim 1, 2, 3, 4, 5, 6 or 7, wherein a fourth main groove extending in a tire circumferential direction is provided between the first main groove and the third main groove.   The pneumatic tire according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein a large number of sipes extending in the tire width direction are formed on the tread surface.

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