JP2008120174A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve improvement of both performance on ice and snow and partial wear resistance. <P>SOLUTION: On a central portion in the tire width direction W of each large block 19, a circumferential sipe 23 extended in the tire circumferential direction C and dividing the large block 19 into a pair of small blocks 19 is formed. Width direction sipes 25, 27 extended in the tire width direction W are formed on the small blocks 19. Each of the circumferential sipes 23 has an appropriate number of sipe parallel parts 23a extended in the tire circumferential direction C in parallel and an appropriate number of sipe inclination parts 23b inclined to the tire circumferential direction C. In each of the circumferential direction sipes 23, the depth of the sipe inclination part 23b is set smaller than that of the sipe parallel part 23a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire such as a heavy-duty pneumatic tire capable of achieving both improvement in performance on snow and snow and improvement in uneven wear performance.

  Various pneumatic tires such as heavy-duty pneumatic tires have been developed in order to improve performance on ice and snow, and as a prior art of a pneumatic tire, there is one disclosed in Patent Document 1, The structure of the characteristic part of the pneumatic tire is as follows.

  That is, the tread portion in the pneumatic tire according to the prior art is provided with a plurality of main grooves extending in the tire circumferential direction, and a plurality of main grooves and tread ends are provided in the tire circumferential direction. A land portion row (a center land portion row, a pair of second land portion rows, and a pair of shoulder land portion rows) is partitioned in the tire width direction.

  A plurality of first lug grooves extending in the tire width direction are spaced apart in the tire circumferential direction on one side portion in the tire width direction of any of the land portion rows (the center land portion row and the pair of second land portion rows). One end of each first lug groove is opened to the main groove, and the other end of each first lug groove is terminated to any land portion row. Further, a plurality of second lug grooves extending in the tire width direction are provided at intervals in the tire circumferential direction on the other side portion in the tire width direction of any land portion row, and each second lug is provided. One end of each groove is terminated in one of the land portion rows, and the other end of each second lug groove is opened in the main groove. Furthermore, in any land portion row, a plurality of communicating sipes that connect the first lug groove and the second lug groove that are in proximity to each other are formed at intervals in the tire circumferential direction.

One of the land rows is partitioned into a plurality of large blocks in the tire circumferential direction by the plurality of main grooves, the plurality of first lug grooves, the plurality of second lug grooves, and the plurality of communicating sipes. ing. Further, a circumferential sipe extending in the tire width direction and divided into a pair of small blocks is formed in the center portion in the tire width direction of each large block, and each small block extends in the tire width direction. Each of the width direction sipes is formed.
JP 2005-1997768 A

  By the way, in the pneumatic tire according to the prior art, in order to improve the performance on snow and snow, by increasing the number of small blocks pitch (number of small blocks per land row) or the number of width direction sipes, It is necessary to increase the edge effect by increasing the edge component in the tire width direction.

  On the other hand, if the pitch number of the small blocks or the number of sipes in the width direction is increased, the rigidity of the large blocks is reduced, and the deformation of the large blocks due to the force received from the road surface during traveling increases. Therefore, uneven wear such as heel and toe wear and center wear is likely to occur, leading to a decrease in uneven wear resistance performance.

  That is, in the pneumatic tire according to the prior art, there is a problem that it is extremely difficult to achieve both improvement in performance on ice and snow and improvement in uneven wear resistance.

  Therefore, the present invention can solve the above-mentioned conventional problems, and even if the number of small blocks is increased or the number of width-direction sipes is increased, deformation of the large block due to the force received from the road surface during traveling is suppressed. An object of the present invention is to provide a pneumatic tire having a novel structure that can be used.

  A first feature of the present invention (feature of the invention described in claim 1) is that a plurality of main grooves extending in the tire circumferential direction are provided in the tread portion, and the tire circumference is defined by the plurality of main grooves and tread ends. A plurality of land portion rows extending in the tire direction are partitioned in the tire width direction, and at least one of the land portion rows in the tire width direction has a plurality of first lug grooves extending in the tire width direction. One end of each first lug groove is opened in the main groove, and the other end of each first lug groove is terminated in any of the land portion rows, respectively, A plurality of second lug grooves extending in the tire width direction are provided on the other side portion in the tire width direction of the land portion row at intervals in the tire circumferential direction, and one end of each second lug groove is one of the land Each of the second lug grooves is terminated in the row and the other end of each second lug groove is connected to the main groove. A plurality of communication sipes that are open and are in close proximity to any one of the land portion rows and that communicate with the first lug groove and the second lug groove are formed at intervals in the tire circumferential direction. The main row groove, the plurality of first lug grooves, the plurality of second lug grooves, and the plurality of communication sipe form one of the land portion rows in the tire circumferential direction. Each of the large blocks is formed with a circumferential sipe extending in the tire circumferential direction and divided into a pair of small blocks at the center portion in the tire width direction, and the small block is formed with a width sipe extending in the tire width direction. In the pneumatic tire, each circumferential sipe has an appropriate number (one or more) of sipe parallel portions extending in parallel to the tire circumferential direction and an appropriate number of sipe inclined portions inclined with respect to the tire circumferential direction. , Each circumferential direction It is summarized as the depth of the sipe inclined portion in-flop is shallower than the depth of the sipe parallel portion.

  According to the first feature, a restraining action is exerted on the pair of small blocks in each large block so as to close the sipe inclined portion in the circumferential sipe by the force received from the road surface when depressing. On the other hand, due to the force received from the road surface at the time of kicking, the pair of small blocks in each large block tends to have a separating action so as to open the sipe inclined portion in the circumferential sipe. Since the depth of the sipe inclined portion is shallower than the depth of the sipe parallel portion, the separating action of the pair of small blocks in each large block can be mitigated. Thereby, even if the pitch number of the small block or the number of the sipe in the width direction is increased, the deformation of the large block due to the force received from the road surface during traveling is suppressed, and the slippage amount of the large block at the time of kicking Can be reduced.

  In addition to the first feature, the second feature of the present invention (feature of the invention described in claim 2) is the length of a projection of an appropriate number of the sipe inclined portions in each circumferential sipe in the tire width direction. The gist is that the total is 10 to 50% of the length of the large block in the tire width direction.

  The third feature of the present invention (the feature of the invention described in claim 3) is that, in addition to the first feature or the second feature, the depth of the sipe inclined portion in each circumferential sipe is the sipe parallel portion. The gist is 40 to 80% of the depth.

  According to the invention of any one of claims 1 to 3, even if the pitch number of the small block or the number of the width direction sipes is increased, it depends on the force received from the road surface during traveling. The deformation of the large block can be suppressed and the amount of slippage of the large block during kicking can be reduced, so that the edge effect can be increased by increasing the edge component in the tire width direction, and the heel and toe Uneven wear such as wear and center wear can be made difficult to occur. Therefore, it is possible to achieve both improvement in performance on ice and snow and improvement in uneven wear resistance.

  An embodiment of the present invention will be described with reference to FIGS.

  Here, FIG. 1 is a plan development view of a part of a tread portion in a pneumatic tire according to an embodiment of the present invention, FIG. 2A is an enlarged view of a block according to the embodiment of the present invention, and FIG. ) Is a perspective view of a circumferential sipe according to an embodiment of the present invention, and FIGS. 3A and 3B are views of stepping and kicking out when the depth of the sipe inclined portion is shallower than the depth of the sipe parallel portion. FIGS. 4A and 4B show the state of the large block at the time of stepping and kicking out when the depth of the sipe inclined portion is the same as the depth of the sipe parallel portion. FIG.

  As shown in FIG. 1, the tread 3 in the pneumatic tire 1 according to the embodiment of the present invention is provided with a plurality of main grooves 5 extending in the tire circumferential direction C, and the plurality of main grooves 5 and A plurality of land portion rows 7, 9, and 11 extending in the tire circumferential direction C are partitioned in the tire width direction W by the tread end E. The plurality of land portion rows 7, 9, and 11 include a center land portion row 7, a pair of second land portion rows 9 arranged outside the center land portion row 7 in the tire width direction W, and a pair of second land rows. It consists of a pair of shoulder land portion rows 11 arranged outside the portion row 9 in the tire width direction W.

  On one side portion in the tire width direction W of the center land portion row 7 and the pair of second land portion rows 9 (hereinafter, referred to as appropriate land portion rows 7 (9)), a plurality of first portions extending in the tire width direction W are provided. 1 lug grooves 13 are provided at intervals in the tire circumferential direction C, one end of each first lug groove 13 is opened in the main groove 5, and the other end of each first lug groove 13 is Each is terminated at an appropriate land portion row 7 (9). Further, a plurality of second lug grooves 15 extending in the tire width direction W are provided at intervals in the tire circumferential direction C on the other side portion of the appropriate land portion row 7 (9) in the tire width direction W. One end of each second lug groove 15 is terminated to an appropriate land portion row 7 (9), and the other end of each second lug groove 15 is opened to the main groove 5 respectively. . Further, in the appropriate land portion row 7 (9), a plurality of communicating sipes 17 that communicate the first lug groove 13 and the second lug groove 15 that are in a close relationship are formed at intervals in the tire circumferential direction C. ing.

  As shown in FIG. 1 and FIG. 2A, the plurality of main grooves 5, the plurality of first lug grooves 13, the plurality of second lug grooves 15, and the plurality of communicating sipes 17 The partial row 7 (9) is partitioned into a plurality of large blocks 19 in the tire circumferential direction C. In addition, a circumferential sipe 23 that extends in a zigzag manner in the tire circumferential direction C and is divided into a pair of small blocks 21 is formed at the central portion of each large block 19 in the tire width direction W. Further, each small block 21 is provided with four width-direction sipes 25 extending in the tire width direction W so as to be divided in the tire circumferential direction C, and the edge of each small block 21 on the main groove 5 side. In each portion, an auxiliary width direction sipe 27 extending in the tire width direction is formed.

  Next, the main part of the embodiment of the present invention will be described.

  As shown in FIGS. 2 (a) and 2 (b), each circumferential sipe 23 has an appropriate number (in the embodiment of the present invention, a plurality) of sipe parallel portions 23a extending in parallel to the tire circumferential direction C. Each of the sipe inclined portions 23b in each circumferential sipe 23 has an appropriate number of sipe inclined portions 23b (one in the embodiment of the present invention) inclined with respect to the tire circumferential direction C. The depth is shallower than the depth of the sipe parallel part 23a. As a result, the separating action acts to open the sipe inclined portion 23b in the circumferential sipe 23 to the pair of small blocks 21 in each large block 19 by the force F (see FIG. 3B) received from the road surface when kicking. In addition, the separating action of the pair of small blocks 21 in each large block 19 can be relaxed.

  The depth of the sipe inclined part 23b in each circumferential sipe 23 is 40 to 80% of the depth of the sipe parallel part 23a. Here, the reason why the depth of the sipe inclined portion 23b in each circumferential sipe 23 is set to 40% or more of the depth of the sipe parallel portion 23a is less than 40% of the depth of the sipe parallel portion 23a. This is because the depth of the portion 23b becomes too shallow and disappears early due to wear. On the other hand, the reason why the depth of the sipe inclined portion 23b in each circumferential sipe 23 is set to 80% or less of the depth of the sipe parallel portion 23a is that the depth of the sipe inclined portion 23b exceeds 80% of the depth of the sipe parallel portion 23a. This is because it becomes difficult to sufficiently relax the separation action of the pair of small blocks 21 in each large block 19.

  Further, the total length of projections of the appropriate number of sipe inclined portions 23b in each circumferential sipe 23 in the tire width direction W (in the embodiment of the present invention, one sipe inclined portion 23b in each circumferential sipe 23). Is preferably 10 to 50% of the length of the large block 19 in the tire width direction W. Here, the total length of projections of the appropriate number of sipe inclined portions 23b in each circumferential sipe 23 in the tire width direction W is set to 10% or more of the length of the large block 19 in the tire width direction W. This is because if the length of the block 19 in the tire width direction W is less than 10%, the restraining action of the pair of small blocks 21 in each large block 19 does not work sufficiently. On the other hand, the total length of projections of the appropriate number of sipe inclined portions 23b in the circumferential sipe 23 in the tire width direction W is less than 50% of the length of the large block 19 in the tire width direction W. If it exceeds 50% of the length of 19 in the tire width direction W, the length of the small block 21 in the tire width direction W becomes short, and it becomes difficult to sufficiently suppress the occurrence of block chipping and the like.

  In addition, although R process is given to the both ends of the sipe bottom part of the sipe inclination part 23b in each circumferential direction sipe 23, you may make it perform a chamfering process.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  As shown in FIG. 3A and FIG. 4A, the pair of small blocks 21 in each large block 19 is closed to the sipe inclined portion 23b in the circumferential sipe 23 by the force F received from the road surface when stepped on. The restraining action works. On the other hand, as shown in FIG. 4 (b), a pair of small blocks 21 in each large block 19 are separated by a force F received from the road surface at the time of kicking so as to open a sipe inclined portion 23b in the circumferential sipe 23. However, since the depth of the sipe inclined portion 23b in each circumferential sipe 23 is shallower than the depth of the sipe parallel portion 23a, as shown in FIG. The separation action of the block 21 can be relaxed. Thereby, even if the pitch number of the small block 21 or the number of the width direction sipes 25 and 27 (including the auxiliary width direction sipes 27) is increased, the deformation of the large block 19 due to the force F received from the road surface during traveling is suppressed. At the same time, the sliding amount of the large block 19 when kicking out can be reduced.

  Therefore, according to the pneumatic tire 1 according to the embodiment of the present invention, the edge component in the tire width direction can be increased to enhance the edge effect, and uneven wear such as heel and toe wear and center wear occurs. Can be difficult. Therefore, it is possible to achieve both improvement in performance on ice and snow and improvement in uneven wear resistance.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, In addition, it can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

  (i) The pneumatic tire 1 according to the embodiment of the present invention (the depth of the sipe parallel part 23a is 13.5 mm, the depth of the sipe inclined part 23b is 10.0 mm) is the invention product 1 according to the embodiment of the present invention. The pneumatic tire 1 (the depth of the sipe parallel portion 23a is 13.5 mm, the depth of the sipe inclined portion 23b is 6.5 mm) is the invention product 2, and the sipe parallel portion 23a and the sipe inclined portion 23b have the same depth. A pneumatic tire according to a comparative example having a configuration substantially the same as that of the pneumatic tire 1 according to the embodiment of the present invention (the depth of the sipe parallel portion 23a is 13.5 mm and the depth of the sipe inclined portion 23b is 13.5 mm). As comparative products, they were each prototyped under a predetermined tire size (11R22.5). Next, the inventive product 1, the inventive product 2, and the comparative product are assembled to a rim (rim width 7.50 inches) and filled with air of 900 KPa. And the partial wear test and the traction test on ice were done in the state which mounted | wore the vehicle (2-D * 4 truck) with the invention 1, invention 2, and the comparison goods, respectively.

(ii) Uneven wear test (heel and toe wear and center wear test)
The uneven wear test was carried out on a general road (average speed 60 km / h), running 20,000 km, 40,000 km, and kicking at the large block 19 in the center land section row 7 when traveling 20,000 km and 40,000 km. This is done by calculating the average value of the step amount on the side and the stepping side (heel toe step amount), and the results (heel and toe wear test results) are summarized as shown in Table 1 below. In addition, the test result of heel and toe wear shows that heel and toe wear hardly occurs as the numerical value is smaller.

即ち、表１に示すように、発明品1及び発明品2は、比較品よりもヒールアンドトウ摩耗が生じ難くいことが確認された。

That is, as shown in Table 1, it was confirmed that Invention 1 and Invention 2 are less susceptible to heel and toe wear than the comparative product.

  The uneven wear test was performed by calculating the average value of the difference in the depth of the remaining grooves in the center portion and the shoulder portion of the tread 3 during 20,000 km travel and 40,000 km travel. The test results are summarized as shown in Table 2 below. Note that the center wear test results indicate that the smaller the value, the less likely the center wear occurs.

即ち、表２に示すように、発明品1及び発明品2は、比較品よりもセンター摩耗が生じ難くいことが確認された。

That is, as shown in Table 2, it was confirmed that the inventive product 1 and the inventive product 2 are less likely to cause center wear than the comparative product.

(iii) On-ice Traction Test The on-ice traction test is started with idling (5 km / h) to 3-speed accelerator on (engine speed 2000 rpm) on the ice course of the test course when the wear rate is 0% and the wear rate is 40%. The results of the traction test on ice are summarized as shown in Table 3 below. The results of the traction test on ice are indexed, and the larger the value, the higher the traction performance on ice.

即ち、表１に示すように、発明品1及び発明品2は、比較品と略同じように氷上トラクション性能を有していることが確認された。

That is, as shown in Table 1, it was confirmed that Invention 1 and Invention 2 have traction performance on ice in substantially the same manner as the comparative product.

It is a plane development view of a part of a tread part in a pneumatic tire concerning an embodiment of the present invention. 2A is an enlarged view of a block according to the embodiment of the present invention, and FIG. 2B is a perspective view of a circumferential sipe according to the embodiment of the present invention. FIGS. 3A and 3B are views showing the state of the large block when stepping on and kicking out when the depth of the sipe inclined portion is shallower than the depth of the sipe parallel portion. FIGS. 4A and 4B are views showing a state of a large block at the time of stepping and kicking out when the depth of the sipe inclined portion is the same as the depth of the sipe parallel portion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 3 Tread 5 Main groove 7 Center land part row | line 9 Second land part row | line | column 11 Shoulder land portion row | line | column 13 1st lug groove 15 2nd lug groove 17 Communication sipes 19 Large block 21 Small block 23 Circumferential sipe 23a Sipe parallel Part 23b sipe inclined part 25 width direction sipe 27 auxiliary width direction sipe

Claims (3)

A plurality of main grooves extending in the tire circumferential direction are provided in the tread portion, and a plurality of land portion rows extending in the tire circumferential direction by the plurality of main grooves and tread ends are partitioned in the tire width direction, and at least one of them A plurality of first lug grooves extending in the tire width direction are provided at one side portion in the tire width direction of the land portion row at intervals in the tire circumferential direction, and one end of each first lug groove is the main groove. And the other end of each of the first lug grooves is terminated at any one of the land portion rows, and extends in the tire width direction at the other side portion in the tire width direction of any of the land portion rows. Second lug grooves are provided at intervals in the tire circumferential direction, one end of each second lug groove is terminated in one of the land portion rows, and the other end of each second lug groove is in the main groove Each open and in close proximity to any of the land rows A plurality of communicating sipes communicating the first lug groove and the second lug groove are formed at intervals in the tire circumferential direction, the plurality of main grooves, the plurality of first lug grooves, the plurality of One of the land portion rows is partitioned into a plurality of large blocks in the tire circumferential direction by the second lug grooves and the plurality of communicating sipes, and extends in the tire circumferential direction at a central portion in the tire width direction of each large block. And in the pneumatic tire in which a circumferential sipe that is divided into a pair of small blocks is formed, and a width sipe extending in the tire width direction is formed in the small block,
Each circumferential sipe has an appropriate number of sipe parallel portions extending in parallel in the tire circumferential direction and an appropriate number of sipe inclined portions inclined with respect to the tire circumferential direction, and each of the sipe inclined portions in each circumferential sipe A pneumatic tire characterized in that a depth is shallower than a depth of the sipe parallel part.   The total length of projections of an appropriate number of the sipe inclined portions in each circumferential sipe in the tire width direction is 10 to 50% of the length in the tire width direction of the large block. The described pneumatic tire.   The pneumatic tire according to claim 1 or 2, wherein a depth of the sipe inclined portion in each circumferential sipe is 40 to 80% of a depth of the sipe parallel portion.

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