JP2005349970A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for making on-ice performance and on-snow performance compatible in a well-balanced state. <P>SOLUTION: A block row including a large long size block 7 corresponding to at least the 3-pitch length of a shoulder side block row, is formed by arranging a specific L-shaped inclined auxiliary groove 5 at a pitch in a land part R1 between a first peripheral directional main groove 2 of a central area of a tread surface 1 and a second peripheral directional main groove 3 on its outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire in which both on-ice performance and on-snow performance are balanced.

  Conventionally, many winter tires (studless tires) employ a block pattern as illustrated in FIG. 3 and each block has a sipe extending in the tire width direction. In order to improve the on-ice performance of such tires, it is necessary to reduce the groove area ratio and increase the ground contact area as much as possible. However, simply reducing the groove area ratio reduces the formation volume of the snow column, so the performance on snow is reduced. The performance on ice and the performance on snow are in a trade-off relationship. In order to make these performances compatible, a tread pattern as disclosed in, for example, Patent Documents 1 and 2 has been proposed.

  The tread pattern of Patent Document 1 is formed by forming ribs along the tire equator line and arranging a number of substantially triangular blocks on both sides thereof. However, in this tread pattern, the lug grooves that define the blocks communicate directly with the main grooves that define the ribs, and only one rib is formed at the center, so the groove area ratio in the tire central region increases. Therefore, there is a problem that the performance on ice cannot be sufficiently improved.

Moreover, since the tread pattern of Patent Document 2 forms a thick groove along the tire equator line and ribs are arranged on both sides thereof, the rigidity of the center area is increased, but the lug groove extends to the tire central area. There is a problem that the groove area ratio in the tire central region becomes large and the performance on ice cannot be improved so much.
JP 2000-255217 A JP 2000-219014 A

  An object of the present invention is to solve the conventional problems that the above-mentioned performance on ice tends to be insufficient as compared with the performance on snow as described above, and is an air in which the performance on ice and the performance on snow are balanced. The purpose is to provide tires.

  In order to achieve the above object, the present invention provides two inventions. A pneumatic tire according to a first aspect of the present invention includes a first circumferential main groove extending in the circumferential direction of the pair of left and right tires in the central region of the tread surface, and a tire circumferential direction on both outer sides of the pair of left and right first circumferential main grooves. And a land portion between the pair of left and right first circumferential main grooves is formed on the rib, and a land portion between the second circumferential main groove and the shoulder end portion is provided. A tire circumference corresponding to at least two pitch lengths of the block row is formed in a block row divided by a plurality of lug grooves and in a land portion between the first circumferential main groove and the second circumferential main groove. A plurality of L-shaped inclined sub-grooves having a length in the direction are arranged in a pitch independently from each other, one end of the L-shaped inclined sub-groove is connected to the first circumferential main groove, and the other end And connecting the inner end of the lug groove to the middle region, corresponding to at least 3 pitch lengths of the block row It is characterized in that the formation of the block row including the long blocks with the tire circumferential direction length.

  A pneumatic tire according to a second aspect of the present invention includes a first circumferential main groove extending in the tire circumferential direction in the central region of the tread surface, and tire circumferential directions on both outer sides of the first circumferential main groove. A second circumferential main groove extending, a land portion between the second circumferential main groove and the shoulder end is formed in a block row divided by a plurality of lug grooves, and the first circumferential main A plurality of L-shaped inclined sub-grooves having a tire circumferential direction length corresponding to at least two pitch lengths of the block row are arranged in a pitch independently from each other in a land portion between the groove and the second circumferential main groove, At least one end of the L-shaped inclined sub-groove is connected to the first circumferential main groove, and the inner end of the lug groove is connected to the other end and the intermediate region, A block row including a long block having a tire circumferential length corresponding to 3 pitch lengths is formed. It is characterized in.

  In the first and second aspects of the present invention, a specific L-shaped inclined sub-groove is formed in the land portion between the first circumferential main groove in the central region of the tread surface and the second circumferential main groove outside the tread surface. By arranging the pitch, a block row including a large long block corresponding to at least three pitch lengths of the block block on the shoulder side is formed, so that the block rigidity and the actual ground contact area in the tire central region are ensured. To improve braking performance and turning performance on the road surface on ice, further improve the performance on ice, and improve the traction performance on the snow road surface with the L-shaped inclined sub-grooves together with the lug grooves forming the block rows on the shoulder side In addition, the performance on ice and the performance on snow can be balanced. In particular, in the first invention, the first circumferential main grooves are arranged in a pair on the left and right sides, and the land portion between them is formed in the rib, whereby the on-ice performance can be further enhanced.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals are assigned to the common components of the configurations of the first invention and the second invention.

  FIG. 1 shows a tread surface of a pneumatic tire according to a first embodiment of the present invention.

  In FIG. 1, a tread surface 1 of a pneumatic tire has a first circumferential main groove 2, 2 extending in the center region in a pair of left and right tire circumferential directions, and both outer sides of the first circumferential main groove 2, 2. Second circumferential main grooves 3 and 3 extending in the tire circumferential direction are formed. Then, a land portion R0 (hereinafter referred to as a center land portion R0) between the pair of left and right first circumferential main grooves 2, 2 is formed on the rib, and the second circumferential main grooves 3, 3 and the shoulder end portion 6 A land portion R2 (hereinafter, referred to as a second land portion R2) is divided into a plurality of lug grooves 4 to form a block row.

  The land portion R1 between the first circumferential main grooves 2 and 2 and the second circumferential main grooves 3 and 3 (hereinafter referred to as the first land portion R1) is a block row forming the second land portion R2. A plurality of L-shaped inclined sub-grooves 5 having a tire circumferential length corresponding to at least two pitch lengths are pitch-independently arranged, and one end portion 5x of the L-shaped inclined sub-groove 5 is arranged in the first circumferential direction. The tire circumference corresponding to at least three pitch lengths of the block row that connects the main groove 2 and connects the inner end portion of the lug groove 4 to the other end portion 5y and the intermediate region 5z to form the second land portion R2. It forms in the block row | line | column containing the elongate block 7 which has a direction length.

  FIG. 2 shows a tread surface of a pneumatic tire according to the second embodiment of the present invention.

  In FIG. 2, the tread surface 1 of the pneumatic tire has a first circumferential main groove 2 extending in the tire circumferential direction in the central region, and tire circumferential directions on both outer sides of the first circumferential main groove 2. Are formed in the second circumferential main grooves 3 and 3. And land part R2 (henceforth 2nd land part R2) between the 2nd circumferential direction main groove 3 and the shoulder edge part 6 is divided by the several lug groove 4, and is formed in the block row | line | column.

  The land portion R1 between the first circumferential main groove 2 and the second circumferential main groove 3 (hereinafter referred to as the first land portion R1) has at least two pitch lengths of the block row forming the second land portion R2. A plurality of L-shaped inclined sub-grooves 5 having tire circumferential lengths corresponding to the above are arranged in a pitch-independent manner, and one end portion 5x of the L-shaped inclined sub-groove 5 is connected to the first circumferential main groove 2 While connecting, the inner edge part of the lug groove 4 is connected with the other edge part 5y and the intermediate | middle area 5z, and the tire circumferential direction length corresponded to at least 3 pitch length of the block row | line | column which forms 2nd land part R2. It forms in the block row | line | column containing the elongate block 7 which has.

  In the present invention, the aforementioned L-shaped inclined sub-groove 5 is constituted by a first inclined sub-groove 5a that is inclined in the tire circumferential direction and a second inclined sub-groove 5b that is inclined in the tire width direction. Moreover, although the case where the lug groove 4 connected to the intermediate region 5z of the L-shaped inclined sub-groove 5 is one in the embodiment described above, a plurality of lug grooves 4 may be connected. .

  By configuring as described above, the present invention improves the braking performance and turning performance on the road surface on ice by ensuring the block rigidity and the actual ground contact area in the tire central region, further improving the performance on ice, and L Since the slanted sub-grooves 5 together with the lug grooves 4 forming the shoulder side row of blocks improve the traction performance on the road surface on snow, the performance on ice and the performance on snow can be balanced. In particular, in the first embodiment, the on-ice performance can be further enhanced by arranging the first circumferential main grooves 2 in a pair on the left and right sides and forming the land portion R0 therebetween as a rib.

  In the first embodiment, in order to improve the performance on ice and the performance on snow in a well-balanced manner, the connection position between the end 5y of the L-shaped inclined sub-groove 5 and the inner end of the lug groove 4 is determined from the tire equator line CL. It is preferable to arrange in a region corresponding to 1/8 to 1/4 of the tire ground contact width W. In the region less than 1/8 of the tire ground contact width W from the tire equator line CL, the block rigidity and the actual ground contact area in the tire central region are insufficient, and a sufficient improvement effect on ice performance cannot be obtained. Then, the length of the lug groove 4 is insufficient, and a sufficient effect of improving the performance on snow cannot be obtained.

  In the second embodiment, the connection position between the end 5y of the L-shaped inclined sub-groove 5 and the inner end of the lug groove 4 is set to 1/10 to 1/1 of the tire ground contact width W from the tire equator line CL. It is preferable to arrange in a region corresponding to 4. In the region less than 1/10 of the tire ground contact width W from the tire equator line CL, the block rigidity and the actual ground contact area in the tire central region are insufficient, and a sufficient improvement effect on ice performance cannot be obtained. Then, the length of the lug groove 4 is insufficient, and a sufficient effect of improving the performance on snow cannot be obtained.

  The tire contact width in the present invention refers to a contact width in a state where a normal load is applied to a tire filled with a normal internal pressure, and is a ground contact in a contact area indicated between the shoulder end portions 6 and 6 in FIGS. Say width.

  In the present invention, the inclination angle α of the first inclined subgroove 5a constituting the L-shaped inclined subgroove 5 with respect to the tire circumferential direction is set to 3 to 15 °, and the inclination angle β of the second inclined subgroove 5b with respect to the tire width direction is set. It is preferable to set it as 5-25 degrees. If the inclination angles α and β are out of the above range, the balance of the size of the long block 7 between the tire equator line CL side and the shoulder side in the first land portion R1 is lost, making it difficult to achieve both on-ice performance and on-snow performance. . 1 and 2 show the case where the inclination direction of the first inclined sub-groove 5a is rising to the right and the inclination direction of the second inclined sub-groove 5b is decreasing to the right. The inclination direction may be downwardly inclined, and the inclination direction of the second inclined sub-groove 5b may be upwardly inclined. Even in this case, the inclination angles α and β described above are set in the above range.

  In the pneumatic tire 1 of the present invention, the groove area ratio in the contact area of the tread surface 1 is 25 to 40%, preferably 28 to 35%. Further, the groove area ratio on the center side of the ground contact region may be adjusted to be smaller than the groove area ratio on the shoulder side. By adjusting in this way, the performance on ice and the performance on snow can be improved with a better balance.

  Furthermore, in order to ensure good on-ice performance, a plurality of sipes extending generally in the tire width direction over the entire land portion may be formed in each land portion. In this case, in the first embodiment, the sipe interval in the tire land direction in the center land portion R0 and the first land portion R1 may be smaller than the sipe interval in the second land portion R2. Moreover, in 2nd embodiment, it is good to make the space | interval of the sipe with respect to the tire circumferential direction in 1st land part R1 smaller than the space | interval of the sipe in 2nd land part R2. Thereby, performance on ice can be improved further.

  In the first embodiment, the width of the center land portion R0 may be adjusted to be in the range of 5 to 20% of the tire ground contact width W. If the tire ground contact width W is less than 5%, the rigidity of the center land portion R0 in the tire width direction is insufficient and the turning performance on ice is reduced, and if it exceeds 20%, turning performance and traction performance on a snowy road surface are difficult to obtain. At the same time, the difference in rigidity between the center land portion R0 and the first land portion R1 becomes too large, and wear tends to occur in the tire central region.

  In addition to the sipe, the center land portion R0 may be formed with a narrow groove having a width of 1 to 4 mm extending in the tire width direction at a predetermined interval in the tire circumferential direction in combination with the sipe or instead of the sipe. Thereby, the traction property can be further improved while maintaining the performance on ice.

  As described above, in the present invention, a specific L-shaped inclined sub-groove is formed in the land portion R1 between the first circumferential main groove 2 in the central region of the tread surface 1 and the second circumferential main groove 3 outside thereof. By securing the block rigidity and the actual ground contact area in the tire central region by forming a block row including a large long block 7 corresponding to at least three pitch lengths of the block row on the shoulder side by arranging the pitch. In order to further improve the performance on ice, and to improve the traction performance on the road surface on snow with the L-shaped inclined sub-groove 5 and the lug groove 4, the tread surface 1 The groove width of the first circumferential main groove 2 and the second circumferential main groove 3 to be formed on each other is preferably 4 to 20 mm, and the L-shaped inclined sub-groove 5 is preferably 3 to 15 mm. Furthermore, the rubber hardness of the tread surface 1 may be set so that the JIS A hardness at 0 ° C. is 40 to 55. If it is less than 40, the rigidity is insufficient and the dry performance decreases, and if it exceeds 55, sufficient frictional force on ice cannot be obtained.

  Conventional tires (conventional examples) and tires according to the present invention (examples 1 and 2) were manufactured with tire sizes common to 195 / 65R15 and different tread patterns as shown in Table 1. The groove area ratio in the tread contact area of each tire was 32.5%, and the rubber hardness of the tread surface was JIS A hardness (0 ° C.) 45.

  For these three types of tires, the braking performance on ice and the running performance on snow were evaluated by the following methods, respectively, and the results are shown in Table 1 by index display with the conventional example as 100. The larger the value, the better.

[Evaluation of braking performance on ice]
Each tire was filled with an air pressure of 200 kPa and mounted on a domestic 2000 cc vehicle (front wheel). The braking distance was measured by lock braking at a braking speed of 40 km / h on the road surface on ice, and evaluated based on the result.

[Snow performance evaluation on snow]
Similarly to the above, each tire was filled with air pressure 200 kPa and mounted on a domestic 2000 cc vehicle (front wheel), and comprehensive sensory evaluation was performed by a skilled test driver on braking performance, startability, and straightness on a snowy road surface. .

表１から、本発明タイヤは従来タイヤに比較して、氷上性能及び雪上性能がバランス良く両立していることがわかる。

From Table 1, it can be seen that the tire of the present invention has a good balance between the performance on ice and the performance on snow as compared with the conventional tire.

It is a top view which shows the tread surface of the pneumatic tire which consists of 1st embodiment of this invention. It is a top view which shows the tread surface of the pneumatic tire which consists of 2nd embodiment of this invention. It is a top view which illustrates the tread surface of the conventional pneumatic tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread surface 2 1st circumferential direction main groove 3 2nd circumferential direction main groove 4 Lug groove 5 L-shaped inclination subgroove 5a 1st inclination subgroove 5b 2nd inclination subgroove 6 Shoulder edge part 7 Long block

Claims (14)

A first circumferential main groove extending in the tire circumferential direction with a pair of left and right tires in a central region of the tread surface, and a second circumferential main groove extending in the tire circumferential direction on both outer sides of the pair of left and right first circumferential main grooves. Provided,
A land portion between the pair of left and right first circumferential main grooves is formed in a rib, and a land portion between the second circumferential main groove and a shoulder end is formed in a block row divided by a plurality of lug grooves. And
And a plurality of L-shaped inclined sub-grooves having a tire circumferential direction length corresponding to at least two pitch lengths of the block row in a land portion between the first circumferential main groove and the second circumferential main groove. Pitch arrangement is made independently of each other, and one end of the L-shaped inclined sub-groove is connected to the first circumferential main groove, and the inner end of the lug groove is connected to the other end and the intermediate region. A pneumatic tire having a block row including a long block having a tire circumferential length corresponding to at least 3 pitches of the block row.   The connection position of the other end portion of the L-shaped inclined sub-groove and the inner end portion of the lug groove is disposed in a region corresponding to 1/8 to 1/4 of the tire ground contact width from the tire equator. The described pneumatic tire.   The L-shaped inclined sub-groove is formed of a first inclined sub-groove having an inclination angle of 3 to 15 ° with respect to the tire circumferential direction and a second inclined sub-groove having an inclination angle of 5 to 25 ° with respect to the tire width direction. The pneumatic tire according to 1 or 2.   The pneumatic tire according to claim 1, 2, or 3, wherein a width of a land portion between the pair of left and right first circumferential main grooves is 5 to 20% of a tire ground contact width.   The pneumatic tire according to any one of claims 1 to 4, wherein a groove area ratio in a ground contact region of the tread surface is 20 to 40%.   A plurality of sipes extending substantially in the tire width direction are formed in the respective land portions, and the distance between the sipes in the tire circumferential direction is set between the land portions between the pair of left and right first circumferential main grooves and the first circumferential main grooves. The pneumatic tire according to any one of claims 1 to 5, wherein a land portion between the second circumferential main groove and the second circumferential main groove is smaller than a land portion between the second circumferential main groove and a shoulder end portion. .   The pneumatic according to any one of claims 1 to 6, wherein a narrow groove having a width of 1 to 4 mm extending in a tire width direction is formed at a predetermined interval in a circumferential direction of a land portion between the pair of left and right first circumferential main grooves. tire.   The groove width of the first circumferential main groove and the second circumferential main groove is 4 to 20 mm, and the groove width of the L-shaped inclined subgroove is 3 to 15 mm. Pneumatic tires. A first circumferential main groove extending in the tire circumferential direction in the central region of the tread surface, and second circumferential main grooves extending in the tire circumferential direction on both outer sides of the first circumferential main groove;
The land portion between the second circumferential main groove and the shoulder end is formed into a block row divided by a plurality of lug grooves,
And a plurality of L-shaped inclined sub-grooves having a tire circumferential direction length corresponding to at least two pitch lengths of the block row in a land portion between the first circumferential main groove and the second circumferential main groove. Pitch arrangement is made independently of each other, and one end of the L-shaped inclined sub-groove is connected to the first circumferential main groove, and the inner end of the lug groove is connected to the other end and the intermediate region. A pneumatic tire having a block row including a long block having a tire circumferential length corresponding to at least 3 pitches of the block row.   The connection position of the other end portion of the L-shaped inclined sub-groove and the inner end portion of the lug groove is disposed in a region corresponding to 1/10 to 1/4 of the tire ground contact width from the tire equator. The described pneumatic tire.   The L-shaped inclined sub-groove is formed of a first inclined sub-groove having an inclination angle of 3 to 15 ° with respect to the tire circumferential direction and a second inclined sub-groove having an inclination angle of 5 to 25 ° with respect to the tire width direction. The pneumatic tire according to 9 or 10.   The pneumatic tire according to claim 9, 10 or 11, wherein a groove area ratio in a ground contact region of the tread surface is 20 to 40%.   A plurality of sipes extending substantially in the tire width direction are formed in each land portion, and the spacing of the sipes with respect to the tire circumferential direction is set at the land portion between the first circumferential main groove and the second circumferential main groove. The pneumatic tire according to any one of claims 9 to 12, wherein the pneumatic tire is smaller than a land portion between the second circumferential main groove and a shoulder end portion. 14. The groove width of the first circumferential main groove and the second circumferential main groove is 4 to 25 mm, and the groove width of the bowl-shaped sub-groove is 3 to 15 mm. Pneumatic tire.

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