JP4581732B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that improves the skid resistance in wet and snow conditions while maintaining braking performance.

  Conventionally, a pneumatic tire in which a sipe extending in the tire circumferential direction is provided on a rib or a block of a tread surface is known (see, for example, Patent Document 1). Due to the edge effect of the sipe extending in the tire circumferential direction, there is an advantage that it is possible to improve the skid resistance when wet or snow (turning performance when wet and snow performance when wearing a chain).

However, when sipes are formed on the ribs and blocks, the rigidity is lowered, so that the braking performance is deteriorated. When one of the performances is improved, the performance of the other is lowered, and there is a problem that it is extremely difficult to achieve both. .
JP 2000-52718 A

  An object of the present invention is to provide a pneumatic tire capable of improving skid resistance when wet and snow while maintaining braking performance.

  In the pneumatic tire of the present invention that achieves the above object, four main grooves extending in the tire circumferential direction are arranged on the tread surface at predetermined intervals in the tire width direction, and the center is located between the main grooves on both outer sides. Three ribs are sectioned in the region by the four main grooves, and only one end of each rib communicates with the main groove, and the first lug grooves extending in the tire width direction are formed at predetermined intervals in the tire circumferential direction. At least one sipe extending in the tire circumferential direction at a position where only one end communicates with the first lug groove and substantially divides the rib width between the first lug grooves of each rib. The tires are arranged in a range of 0 to 5 ° with respect to the tire circumferential length of the sipe in a range of 40 to 60% of the distance between the first lug grooves, and are located outside the outer main grooves. Auxiliary grooves extending in the tire circumferential direction are arranged in the shoulder region, and each auxiliary groove and the outer main groove are arranged. Forming a rib between, characterized in that the second lug grooves extending outward in the tire width direction from each of the auxiliary grooves arranged at predetermined intervals in the tire circumferential direction.

  According to the above-described present invention, the edge effect due to the sipe extending in the tire circumferential direction is generated during wet turning traveling or during chain-attached snow traveling while suppressing the rigidity reduction of the rib in the center region of the tread surface that affects the braking performance. Since it can effectively exhibit side skidding, it is possible to improve the skid resistance when wet and snow (turning performance when wet and snow performance when wearing a chain) while maintaining braking performance. It becomes possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of a pneumatic tire according to the present invention. Four main grooves 2 extending in a straight shape along the tire circumferential direction T are formed on the tread surface 1 at predetermined intervals in the tire width direction. Is provided. The four main grooves 2 are composed of two outer main grooves 2A and 2B and two inner main grooves 2C and 2D. The two outer main grooves 2A and 2B and the two inner main grooves 2C and 2D The main grooves 2C and 2D are arranged symmetrically with respect to the tire center line CL.

  In addition, the main groove | channel 2 said here has the length of 3-8% of groove width GW of tire ground-contact width TW. In addition, the tire contact width TW is the value when the tire is filled with the air pressure corresponding to the maximum load capacity and the load of the maximum load capacity is applied in the air pressure-load capacity correspondence table specified in JATMA (2004 edition). The contact width of the tread surface. However, in the case of a pneumatic tire for a passenger car, the contact width of the tread surface when an air pressure of 180 kPa and a load of 88% of the maximum load capacity are applied.

  In the center region 1A located between the outer main grooves 2A and 2B, three ribs 3 are sectioned by the four main grooves 2. Each rib 3 has a rib width of 10 to 18% of the tire ground contact width TW, and the three ribs 3 are a center rib 3A located at the center on the tire center line CL and side ribs 3B located on both sides thereof. , 3C.

  Only one end of each rib 3 communicates with the main groove 2, and first lug grooves 4 whose other ends are located in the rib 3 are arranged in the tire circumferential direction T at predetermined intervals. Each first lug groove 4 is formed so that the groove width gradually increases from the other end (inner end) to one end (outer end) communicating with the main groove, and from the side not communicating the groove width on the side communicating with the main groove. It is trying to be wide. Thereby, it is easy to drain the water in the first lug groove 4 to the main groove 2.

  In the center rib 3A, the first lug grooves 4C and 4D respectively extend from the inner main grooves 2C and 2D located on both sides toward the inner side in the tire width direction at a position approximately 1/3 of the rib width W1 (33 of the rib width W1). % ± 7% range). The first lug groove 4C extending from one inner main groove 2C is inclined to one side in the tire circumferential direction T (upper side in FIG. 1), and the first lug groove 4D extending from the other inner main groove 2D. Extends incline toward the other side (the lower side in FIG. 1) of the tire circumferential direction T, and the first lug grooves 4C and 4D of the center rib 3A have the same inclination direction with respect to the tire circumferential direction T. It is inclined to.

  In the side ribs 3B and 3C, the first lug grooves 4A and 4B extend from only the outer main grooves 2A and 2B inclining to the position of about 3/4 of the rib width W2 inward in the tire width direction. . The first lug groove 4A extending from one outer main groove 2A is inclined to the other side in the tire circumferential direction T, and the first lug groove 4B extending from the other outer main groove 2B is arranged in the tire circumferential direction T. The first lug grooves 4A and 4B of the side ribs 3B and 3C are inclined to one side, and are in the same inclination direction with respect to the tire circumferential direction T, and the first lug grooves 4C and 4D of the center rib 3A. It is inclined in the direction opposite to the inclination direction with respect to the tire circumferential direction T. In the first lug grooves 4A and 4B, sipes extending from the inner ends of the first lug grooves 4A and 4B to the inner main grooves 2C and 2D may be provided as necessary.

  Between each first lug groove 4 of each rib 3, there is provided a single sipe 5 having only one end communicating with the first lug groove 4 and the other end positioned in the rib 3. Each sipe 5 extends in the tire circumferential direction T in a range of 0 to 5 ° with respect to the tire circumferential direction T. The tire circumferential direction length L1 of each sipe 5 is in the range of 40 to 60% of the distance L2 between the first lug grooves 4 where the sipe 5 is located. In addition, the sipe said by this invention refers to the groove | channel whose width is 1.5 mm or less.

  In the center rib 3A, one sipe 5C, 5D is extended from the inner ends of the first lug grooves 4C, 4D on both sides at positions that substantially divide the rib width W1 into three equal parts. It should be noted that the extension of one sipe 5C, 5D at a position that substantially divides the rib width W1 here into three equals the tire circumferential direction within the range of 33% ± 7% of the rib width W1 from both rib edges. One sipe 5C, 5D extending to T is arranged.

  The sipe 5C extending from one first lug groove 4C extends from the first lug groove 4C in a direction in which the inner end side of the first lug groove 4C is inclined (one side in the tire circumferential direction T). The sipe 5D extending from the other first lug groove 4D extends from the first lug groove 4D in a direction in which the inner end side of the first lug groove 4D is inclined (the other side in the tire circumferential direction T).

  In the side ribs 3B, 3C, one sipe 5A, 5B is extended from each first lug groove 4A, 4B at a position that substantially bisects the rib width W2. Note that extending one sipe 5A, 5B at a position that substantially bisects the rib width W2 referred to herein means that the tire circumference is within a range of 50% ± 10% of the rib width W2 from one rib edge. One sipe 5A, 5B extending in the direction T is arranged.

  The sipe 5A extending from the first lug groove 4A located in the one side rib 3B has a direction (in the tire circumferential direction T) opposite to the direction in which the inner end side of the first lug groove 4A is inclined (the other side in the tire circumferential direction T). One side is extended from the first lug groove 4A. The sipe 5B extending from the first lug groove 4B located on the other side rib 3C has a direction (in the tire circumferential direction T) opposite to the direction in which the inner end side of the first lug groove 4B is inclined (one side in the tire circumferential direction T). One side) is extended from the first lug groove 4B.

  In each shoulder region 1B located outside the outer main grooves 2A, 2B, one auxiliary groove 6 extending in a straight shape in the tire circumferential direction T is disposed, and each auxiliary groove 6 and the outer main groove are arranged. Ribs 7 are formed between 2A and 2B, respectively. The auxiliary groove 6 referred to here is a groove having a groove width of 10 to 30% of the groove width GW of the main groove 2.

  Second lug grooves 8 extending from the auxiliary grooves 6 to the outer side in the tire width direction beyond the position of the tire ground contact width TW are arranged at predetermined intervals in the tire circumferential direction T, and the second lug grooves 8 and the auxiliary grooves 6 Blocks 9 are defined. As described above, the second lug groove 8 is extended from the auxiliary groove 6 without communicating with the main groove 2, thereby suppressing noise caused by the tread pattern. The second lug groove 8 can be extended in a range of ± 20 ° with respect to the tire axial direction.

  Each block 9 is provided with one sipe 10 extending in the tire width direction at a position that substantially bisects the block circumferential length L3. Note that providing one sipe 10 at a position that substantially bisects the block circumferential length L3 referred to here means a range of 50% ± 10% of the block circumferential length L3 from one block edge. One sipe 10 extending in the tire width direction is disposed on the front side.

  The sipe 10 communicates with the auxiliary groove 6 and extends across the rib 7 to a position where it communicates with the outer main grooves 2A and 2B. The sipe 10 opens to the outer main grooves 2A and 2B at positions facing the first lug grooves 4A and 4B. The sipe 10 ensures traction particularly during snow travel. Similarly to the second lug groove 8, the sipe 10 is preferably extended within a range of ± 20 ° with respect to the tire axial direction.

  According to the present invention described above, the three ribs 3 are formed in the center region 1A of the tread surface 1 and the first lug grooves 4 whose one ends communicate with the main groove 2 are formed in the tire circumferential direction T in each rib 3. One which is arranged at a predetermined interval, extends in the tire circumferential direction T at a position where only one end communicates between the first lug grooves 4 and communicates with the first lug grooves 4 and substantially divides the rib widths W1 and W2. The sipe 5 is disposed in a range of 0 to 5 ° with respect to the tire circumferential direction T, and the tire circumferential direction length L1 of the sipe 5 is in a range of 40 to 60% of the distance L2 between the first lug grooves 4. As a result, the edge effect of the sipe 5 extending in the tire circumferential direction T is reduced to a side slip during a wet turn or a chain-attached snow while suppressing a decrease in rigidity of the rib 3 in the center region 1A that affects the braking performance. It becomes possible to demonstrate effectively with respect to it. Therefore, it is possible to improve the skid resistance (wet turning performance when wet and snow performance when wearing a chain) while maintaining braking performance.

  Further, by forming a rib 7 between the auxiliary groove 6 and the outer main groove 2 in the shoulder region 1B, the rib 7 blocks passage noise generated in the center region 1A from escaping outward in the lateral direction of the vehicle. Therefore, passing noise can be improved.

  When the extending angle of the sipe 5 with respect to the tire circumferential direction T exceeds 5 °, the rigidity in the circumferential direction of the portion of the rib 3 divided by the sipe 5 is significantly reduced, which adversely affects braking performance. .

  When the tire circumferential length L1 of the sipe 5 is shorter than 40% of the distance L2 between the first lug grooves 5, the skid performance in wet and snow conditions is effectively improved due to a decrease in the edge component of the sipe 5. It becomes difficult. Conversely, if the tire circumferential length L1 of the sipe 5 exceeds 60% of the distance L2 between the first lug grooves 5, the braking performance deteriorates due to the rigidity of the ribs 7 decreasing.

  In the present invention, as described above, the center rib 3A has the first lug grooves 4C and 4D extending from the inner main grooves 2C and 2D located on both sides to the inside in the tire width direction, respectively, and the rib width W1 is substantially increased. It is preferable to extend the sipes 5C and 5D from the first lug grooves 4C and 4D at positions equally divided into three. When running on a snowy road, the ground contact length of the center rib 3A located on the tire center line CL is particularly long. Therefore, two sipes 5C and 5D communicating with the first lug grooves 4C and 4D are connected to the center rib 3A. By disposing at the position to be divided, the edge effect by sipe can be enhanced while effectively suppressing the decrease in rigidity of the center rib 3A, and the skid resistance during snow can be further improved.

  In addition, since the ground pressure on the side ribs 3B and 3C increases during braking under high load, the side ribs 3B and 3C have the first lug groove only from the outer main grooves 2A and 2B as described above. 4A and 4B are extended inward in the tire width direction, and it is preferable to extend only one sipe 5A and 5B from the first lug grooves 4A and 4B at a position that substantially bisects the rib width W2. Thus, the edge effect by the sipes 5A and 5B can be exhibited while effectively suppressing the rigidity reduction of the side ribs 3B and 3C.

  The number of sipes 5 provided between the first lug grooves 4 is preferably one in order to ensure the rigidity of the ribs in the tire for passenger cars as described above, but may be appropriately set depending on the type and size of the tire. Yes, at least one is enough.

  Although this invention can be preferably used especially for the pneumatic tire for passenger cars, it is not limited to it.

  In the tire having the tire size common to 175 / 65R14 and having the tread pattern shown in FIG. 1, the tire circumferential length L1 of the sipe provided on the rib in the center region is shown in Table 1 with respect to the distance L2 between the first lug grooves. The tires 1 to 3 of the present invention, the comparative tires 1 and 2, and the comparative tire 3 having the tread pattern shown in FIG.

  In FIG. 2, 20 is a tread surface, 21 is a main groove extending in the tire circumferential direction, 22 is a lug groove extending in the tire width direction, 23 is a rib formed between the main grooves 21, and 24 is a main groove 21. And blocks formed by lug grooves 22. The angles of the sipe of the present invention tires 1 to 3 and the comparative tires 1 and 2 with respect to the tire circumferential direction are 0 ° and are common.

  Each test tire is mounted on a rim with a rim size of 14 x 5.5 JJ, mounted on a passenger car with ABS (front-wheel drive car) with an air pressure of 220 kPa, and wet turning performance and snow performance when the chain is installed according to the following test methods. And when the evaluation test of braking performance was done, the result shown in Table 1 was obtained.

Wet turning performance Measure the time required for 5 consecutive round turns at a maximum speed that can be maintained while drawing a circle with a radius of 30 m on a road surface with a depth of 1 mm. Indicated by value. The larger this value, the better the wet turning performance. An index value of 110 or more is considered to have a remarkable effect.

Snow performance when chain is installed (Snow performance with chain)
A chain is attached to the drive wheel, and the time required for a circle to make five consecutive rounds at the maximum speed that can be maintained while drawing a circle with a radius of 50 m on a snowy road surface is measured. It was indicated by an exponent value. The larger this value, the better the snow performance when the chain is attached. An index value of 110 or more is considered to have a remarkable effect.

Braking performance On dry and wet test courses, braking was applied at a speed of 100 km / h, and the distance to stop was measured five times. Results obtained by averaging the results are shown as index values with the comparative tire 3 being 100. The larger this value, the better the braking performance.

表１から、本発明タイヤは、制動性能を維持しながら、ウェット時及びスノー時の耐横滑り性能を改善できることがわかる。

From Table 1, it can be seen that the tire of the present invention can improve the skid resistance when wet and snow while maintaining the braking performance.

It is a principal part expanded view of the tread surface which shows one Embodiment of the pneumatic tire of this invention. 3 is a development view of a main part of a tread surface of a comparative tire 3. FIG.

Explanation of symbols

1 tread surface 1A center region 1B shoulder region 2, 2A, 2B, 2C, 2D main groove 3 rib 3A center rib 3B, 3C side rib 4, 4A, 4B, 4C, 4D first lug groove 5, 5A, 5B, 5C, 5D Sipe 6 Auxiliary groove 7 Rib 8 Second lug groove 9 Block 10 Sipe L1 Length of sipe in tire circumferential direction L2 Distance between first lug grooves L3 Length in block circumferential direction T Tire circumferential direction W1, W2 Rib width

Claims (7)

  Four main grooves extending in the tire circumferential direction are arranged on the tread surface at a predetermined interval in the tire width direction, and three ribs are formed by the four main grooves in a center region located between the main grooves on both outer sides. The first lug grooves that extend in the tire width direction are arranged at predetermined intervals in the tire circumferential direction, and one end of each rib communicates with the main groove. At least one sipe extending in the tire circumferential direction is disposed in a range of 0 to 5 ° with respect to the tire circumferential direction at a position where only one end communicates with the first lug groove and the rib width is substantially equally divided. The length of the sipe in the tire circumferential direction is in the range of 40 to 60% of the distance between the first lug grooves, and auxiliary grooves extending in the tire circumferential direction are provided in both shoulder regions located outside the outer main grooves. Each is arranged and a rib is formed between each auxiliary groove and the outer main groove. Pneumatic tire arranged at predetermined intervals a second lug grooves in the tire circumferential direction that extends toward the outside.   Of the three ribs, the first lug groove extends from the inner main groove located on both sides of the center rib to the center rib located at the center, and the rib width is substantially increased. The pneumatic tire according to claim 1, wherein only one sipe is extended from each first lug groove of the center rib at a position equally divided into three.   Each first lug groove of the center rib is inclined so as to have the same inclination direction with respect to the tire circumferential direction, and each sipe of the center rib is inclined from the first lug groove in a direction in which the inner end side of the first lug groove is inclined. The pneumatic tire according to claim 2 extended.   Among the three ribs, the first lug grooves are extended from the outer main grooves only to the side ribs located on both sides, and the rib width is substantially divided into two equal parts. The pneumatic tire according to claim 1, 2 or 3, wherein only one sipe is extended from each first lug groove of the side rib.   Among the three ribs, the first lug grooves are extended from the outer main grooves only to the side ribs located on both sides, and the rib width is substantially divided into two equal parts. Only one sipe is extended from each first lug groove of the side rib, and each first lug groove of the side rib is in the same inclination direction with respect to the tire circumferential direction, and the tire circumference of the first lug groove of the center rib The pneumatic tire according to claim 3, wherein the sipe is inclined in a direction opposite to an inclination direction with respect to a direction, and each sipe of the side rib extends from the first lug groove in a direction opposite to a direction in which an inner end side of the first lug groove is inclined. .   The pneumatic tire according to any one of claims 1 to 5, wherein each first lug groove is formed to have a wider groove width on the side communicating with the main groove. A block is defined by the second lug groove and the auxiliary groove in both shoulder regions, and each block is provided with one sipe extending in the tire width direction at a position that substantially bisects the block circumferential length. The pneumatic tire according to any one of claims 1 to 6, wherein the sipe is provided to extend to the rib in the shoulder region.

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