JP5465890B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with improved rigidity of a land portion when a lug groove is provided in a shoulder portion.

  2. Description of the Related Art Conventionally, a technique for improving the running performance of a vehicle on an icy and snowy road surface by providing a circumferential groove extending in the circumferential direction and a lug groove or a lateral groove extending in the width direction on the tread surface is known (for example, Patent Document 1) reference).

JP 2007-106167 A

  However, in the conventional pneumatic tire described above, since the depth of the lug groove and the lateral groove is set to be substantially the same, in the portion where the lug groove and the lateral groove overlap in the tire circumferential direction, the rigidity of the tread rubber is reduced. There was a problem that the rigidity of the land portion was reduced.

  An object of the present invention is to provide a pneumatic tire capable of making the land rigidity along the tire circumferential direction uniform at an arbitrary portion in the width direction when a lug groove is formed on a tread surface.

  The first feature of the present invention is a circumferential groove (circumferential groove 10) extending in the tire circumferential direction and a plurality of lug grooves (first lug grooves) provided in the land portion (land portion 31) and extending in the tire width direction. 20 and a second lug groove 40), and one end of both ends in the width direction is open to the outside of the circumferential groove or the ground end (ground end 30), and the lug groove has a predetermined first The opening side of the lug groove (first lug groove 20) and the second lug groove (second lug groove 40) adjacent to the first lug groove in the tire circumferential direction is in contact with the circumferential groove side along the tire circumferential direction. It is a pneumatic tire (pneumatic tire 1) in which lug grooves are arranged so as to alternately change to the end side, and the sum total of the groove depths of the lug grooves in the land portion is substantially the same along the tire circumferential direction. The gist is set.

  Therefore, since the land portion rigidity, which is the rigidity of the tread rubber in the land portion, is uniform along the tire circumferential direction at any part in the width direction, the slip is reduced with respect to the input in the tire circumferential direction and the wear resistance is reduced. improves.

  Another feature of the present invention is that the lug groove is formed in a portion outside the mounting in the tire width direction.

  According to the pneumatic tire according to the present invention, the land portion rigidity, which is the rigidity of the tread rubber in the land portion, is uniform along the tire circumferential direction at any part in the width direction. Sliding is reduced and wear resistance is improved.

1 is a cross-sectional view in the width direction of a pneumatic tire according to an embodiment of the present invention. 2 shows a tread pattern according to an embodiment of the present invention, (a) shows a main part of the tread pattern, (b) is a sectional view of a first lug groove, and (c) is a sectional view of a second lug groove. . The tread pattern for comparing with this embodiment is shown, (a) shows the main part of the tread pattern, (b) is a sectional view of the first lug groove, (c) is the second lug groove. It is sectional drawing. It is a tread pattern of the comparative example in an Example. It is a graph which shows the abrasion loss of the tread edge at the time of driving | running | working with the pneumatic tire which concerns on the example of this invention in an Example.

  Hereinafter, details of a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

<Schematic configuration of pneumatic tire>
FIG. 1 is a cross-sectional view in the width direction of a pneumatic tire according to an embodiment of the present invention.

  The pneumatic tire 1 includes a pair of annular bead cores 2 and 2 that are spaced apart in the tire width direction, a carcass 3 that serves as a skeleton of a tire that connects these bead cores 2 and 2 in a toroidal shape, A belt layer 4 having two layers disposed on a crown portion 3a disposed in the center in the width direction of the carcass 3;

  Further, a crown portion 3 a of the carcass 3, a belt layer 4, and a tread portion 5 made of a tread rubber covering these are formed at the center portion in the width direction of the pneumatic tire 1. Side wall portions 6 and 6 are provided, and a bead portion 7 is formed in the vicinity of the bead core 2 on the inner diameter side of the side wall portion 6. And the said carcass 3 has the folding | returning part 3b which winds the bead core 2 from the tire width direction inner side, and folds back and extends to a radial direction. The belt layer 4 is composed of an inner belt 8 having a large width dimension in the tire width direction and an outer belt 9 disposed on the outer diameter side of the inner belt 8. A circumferential groove 10 extending in the tire circumferential direction is formed on the surface of the tread portion 5.

<Schematic configuration of tread pattern>
2 shows a tread pattern according to an embodiment of the present invention, (a) shows a main part of the tread pattern, (b) is a sectional view of a first lug groove, and (c) is a sectional view of a second lug groove. .

  As shown in FIG. 2 (a), a circumferential groove 10 extends along the tire circumferential direction at the center in the tire width direction, and a first lug is disposed at the widthwise outer end 11 of the circumferential groove 10. The groove 20 extends along the width direction. The widthwise inner end 21 of the first lug groove 20 opens (communication) to the widthwise outer end 11 of the circumferential groove 10, and the grounding end (indicated by a two-dot chain line) 30 from the widthwise inner end 21. Toward the outer end 24 in the width direction.

  A second lug groove 40 is formed adjacent to the first lug groove 20. The width direction outer side end portion 43 of the second lug groove 40 opens to the outside of the ground contact end 30 and extends to the width direction inner end portion 45 toward the inner side in the tire width direction. In addition, the width dimension along the width direction of the 1st lug groove 20 is set to w1, and the width dimension along the width direction of the 2nd lug groove 40 is set to w2.

  Then, as shown in FIG. 2B, the depth of the first lug groove 20 changes with the intermediate portion 25 of the first lug groove 20 corresponding to the widthwise inner end 45 of the second lug groove 40 as a boundary. doing. Specifically, the groove depth in the portion B extending from the width direction outer end 24 to the intermediate portion 25 is set to D1 (out), and the groove in the portion C extending from the intermediate portion 25 to the width direction inner end portion 21 is set. The depth is set to D1 (in). This D 1 (in) is the same as the groove depth D 0 of the circumferential groove 10.

  Further, as shown in FIG. 2C, the depth of the second lug groove 40 changes with the intermediate portion 46 of the second lug groove 40 corresponding to the widthwise outer end 24 of the first lug groove 20 as a boundary. doing. Specifically, the groove depth in the portion A extending from the width direction outer end portion 43 to the intermediate portion 46 is set to D2 (out), and the groove in the portion B extending from the intermediate portion 46 to the width direction inner end portion 45 is set. The depth is set to D2 (in). The D2 (out) is the same as the groove depth D0 of the circumferential groove 10. Further, the relationship of D2 (out) = D1 (out) + D2 (in) = D1 (in) = D0 is satisfied. In addition, the width dimension of the 1st lug groove 20 is W1, and the width dimension of the 2nd lug groove 40 is W2.

  Thus, the sum total of the groove depth in the 1st lug groove 20 and the 2nd lug groove 40 is set uniformly from the earthing | grounding end 30 to the circumferential groove | channel 10. FIG.

  In addition, it is preferable to provide these lug grooves on the mounting outer side of the tread surface of the tire. That is, in the tread pattern shown in FIG. 2, since the lug grooves having the same total groove depth along the tire circumferential direction are provided on the left side of the figure, this pneumatic tire is mounted on the left side of the vehicle. It is preferable.

  FIG. 3 is an enlarged view of a tread pattern for comparison with the present embodiment. In this tread pattern, the total sum of the depths of the lug grooves along the tire circumferential direction differs depending on each part.

  In the vicinity of the center in the width direction, a circumferential groove 110 extends along the tire circumferential direction. An inner lug groove 120 is provided in communication with the circumferential groove 110, and an outer lug groove 140 is disposed adjacent to the inner lug groove 120 in the tire circumferential direction. The outer end portion 143 in the width direction of the outer lug groove 140 opens outward from the ground contact end 30 and extends in the width direction to the inner end portion 145 in the width direction. In the case of this tread pattern, the land portion 131 can be divided into the a portion, the b portion, and the c portion along the inner side in the tire width direction from the ground contact end 30 side.

  Here, the width dimension along the tire width direction of the inner lug groove 120 is W1, and the width dimension of the outer lug groove 140 is W2. The groove depth of the inner lug groove 120 is d1, which is the same as the groove depth d0 of the circumferential groove 110.

  The groove depth d2 of the outer lug groove 140 is also the same as the groove depth d0 of the circumferential groove 110. Therefore, the relationship d1 = d2 = d0 is set.

  Here, in the part a, the sum of the groove depths of the lug grooves is d2, the sum of the groove depths in the part b is d1 + d2, and the sum of the groove depths in the part c is d1. Then, since the groove depth of b part is set larger than a part and c part, the land part rigidity of b part becomes the smallest.

  Below, the effect by embodiment of this invention is demonstrated.

<Operation effect>
(1) A circumferential groove 10 extending in the tire circumferential direction, and a first lug groove 20 and a second lug groove 40 provided in the land portion 31 and extending in the tire width direction, the first lug groove 20 being One end of both ends in the width direction is open to the circumferential groove 10, and the opening side of the second lug groove 40 adjacent to the first lug groove 20 in the tire circumferential direction is disposed on the ground contact end 30 side. ing. Thus, the lug grooves 20 and 40 are arranged so that the opening side is alternately changed to the circumferential groove side and the ground contact end side along the tire circumferential direction, and the groove depth of the lug grooves 20 and 40 in the land portion 31 is changed. The total sum is set substantially the same along the tire circumferential direction.

  As shown in FIG. 2, when the land portion 31 is divided into the A portion, the B portion, and the C portion in the width direction, the groove depth in the A portion is D2 (out), and the total width depth in the B portion is D1. (Out) + D2 (in), and the groove depth at the C portion is D1 (in). Here, since D2 (out) = D1 (in) is set, the sum of the depths of the lug grooves is set to be substantially the same in the width direction. Accordingly, since the land portion rigidity, which is the rigidity of the tread rubber in the land portion 31, is uniform along the tire circumferential direction at any part in the width direction, the slip is reduced with respect to the input in the tire circumferential direction and wear resistance is increased. Will improve.

  (2) The lug groove is formed in a portion outside the mounting in the tire width direction.

  Usually, since the outer part of the tire on the tread surface of the tire is worn significantly, the wear resistance is further improved.

  It should not be understood that the description and the drawings, which form part of the disclosure of the above-described embodiments, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment, a total of two circumferential grooves 10 are provided in a pair of left and right. However, three or more circumferential grooves 10 may be provided, and lug grooves may be arranged on land portions of these circumferential grooves.

  Next, the present invention will be described more specifically through examples.

  A tire having a size of 155 / 65R13 was used as a test tire and mounted on the front wheel of an FF vehicle (Move X-Limited) with an internal pressure of 220 kPa. The load on the tire was 3.8 kN. Among the test tires, the pneumatic tire according to the conventional example has a plurality of lug grooves that are open on the same direction side at both ends in the width direction along the tire circumferential direction. In the pneumatic tire according to the comparative example, as described with reference to FIG. 3, lug grooves having a constant groove depth are alternately arranged along the tire circumferential direction. And the pneumatic tire which concerns on the example of this invention shall have the tread pattern shown in FIG. The groove depths of D1 (out), D1 (in), D2 (out), and D2 (in) were 3.3 mm, 9.9 mm, 3.3 mm, and 9.9 mm, respectively.

  The vehicle traveled 20000 km on a general road, and the wear resistance, drainage performance, and snow running performance were verified. FIG. 4 is a tread pattern of a comparative example in the example, FIG. 5 is a graph showing the wear amount of the tread edge when running with the pneumatic tire according to the example of the invention in the example, the running distance is 5000 km, The average value of the amount of wear in the entire tire circumference at the time points of 7500 km and 10,000 km is shown.

  As shown in FIG. 4, the ground contact 30 disposed on the outer side of the wear was worn after traveling and moved inward in the width direction to 30 ′. In FIG. 5, the solid line P indicates the amount of tire wear when the travel distance is 5000 km, the broken line Q indicates the travel distance is 7500 km, and the alternate long and short dash line R indicates the travel distance when the travel distance is 10,000 km. For example, when the travel distance was 10,000 km, the wear amount near the ground contact edge when the distance in the width direction from the tire center was about 60 mm was 1.7 mm, and the wear amount at the tire center was 0.9 mm.

The above results were put together and Table 1 was created. In Table 1, “on-snow running performance” is a performance test related to braking distance on ice and snow and traction on snow.

  As shown in Table 1, it has been found that the pneumatic tire according to the example of the present invention can obtain higher performance than the conventional example and the comparative example in all of the uneven wear resistance, drainage performance, and running performance on snow.

1 Pneumatic tire 10 Circumferential groove 20 First lug groove (lug groove)
30 Grounding end 40 Second lug groove (lug groove)

Claims (3)

A circumferential groove extending in the tire circumferential direction;
A land portion defined by the circumferential groove and a grounding end;
A pneumatic tire provided in the land portion and provided with a plurality of lug grooves extending in the tire width direction,
The plurality of lug grooves communicate with the circumferential groove, and terminate in the land portion, communicate with the outside of the grounding end, and terminate in the land portion. Including
The first lug grooves and the second lug grooves are alternately provided in the tire circumferential direction, and partially overlap in the tire circumferential direction,
The pneumatic tire according to claim 1, wherein a total sum of the groove depth of the first lug groove and the groove depth of the second lug groove measured in the tire circumferential direction is substantially the same in the entire tire width direction. The groove depth of the first lug groove changes in the tire width direction,
The pneumatic tire according to claim 1, wherein a groove depth of the second lug groove is changed in the tire width direction.   2. The pneumatic tire according to claim 1, wherein the first lug groove and the second lug groove are formed in a portion outside the mounting in the tire width direction.

Images