JP5932866B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire capable of reducing passing noise while maintaining mud performance.

  The following Patent Document 1 proposes a pneumatic tire including at least one zigzag main groove extending continuously in the tire circumferential direction in the tread portion and a lateral groove extending from the zigzag top portion of the main groove to the tread end. ing. The lateral groove includes a groove bottom whose groove depth decreases from one end side to the other end side. In this pneumatic tire, the groove volume of the lateral groove is reduced, the inflow of air from the main groove to the lateral groove is suppressed, and consequently the passing noise is reduced.

JP 11-198612 A

  However, the tire described above has a problem that the mud performance, which is a traction performance in a muddy area, decreases due to a decrease in the groove volume.

  This invention is made | formed in view of the above actual conditions, and makes it the main objective to provide the pneumatic tire which can reduce a passage noise, maintaining a mud performance.

In the present invention, the tread portion is provided with at least one shoulder main groove extending continuously in the tire circumferential direction on the tread end side, and a plurality of shoulder lateral grooves extending from the shoulder main groove to the tread end. The tire main groove includes a first inclined portion and a second inclined portion that is inclined to the opposite side of the first inclined portion, and extends in a zigzag shape. The shoulder main groove is a tire shaft. An outer zigzag top portion that protrudes outward in the direction and an inner zigzag top portion that protrudes inward in the tire axial direction, and the shoulder lateral groove is the same as the second inclined portion from the inner end connected to the first inclined portion The inner end of the shoulder lateral groove is connected so as to form a T-shaped three-way with the first inclined portion, and the first inclined portion is Shi The inner side of the rudder lateral groove includes an inner side closer to the inner zigzag top than the inner end of the shoulder lateral groove, and the outer side closer to the outer zigzag top than the inner end of the shoulder lateral groove. It is characterized by being larger than the groove width .

The pneumatic tire according to the present invention, the in zigzag one pitch of the shoulder main grooves include an outer zigzag top, the inner end of the shoulder lateral grooves, the tread of the tire axial direction inner groove edge of the second inclined portion It is desirable to be located on the inner side in the tire axial direction with respect to the imaginary line extended to the contact end side.

  In the pneumatic tire according to the present invention, it is preferable that a distance between the inner end of the shoulder lateral groove and the imaginary line is in a range of 4.0 mm or less.

  In the pneumatic tire according to the present invention, it is preferable that the outer zigzag top portion of the shoulder main groove extends linearly along the tire circumferential direction.

  In the pneumatic tire according to the present invention, it is desirable that the first inclined portion and the second inclined portion are inclined at an angle of 30 to 40 degrees with respect to the tire circumferential direction.

  In the pneumatic tire according to the present invention, it is desirable that at least an inner portion in the tire axial direction of the shoulder lateral groove is inclined at an angle of 30 to 40 degrees with respect to the tire circumferential direction.

In the pneumatic tire according to the present invention, the shoulder lateral groove includes a first portion extending outward in the tire axial direction from the inner end, and the groove depth of the first portion is equal to the groove depth of the shoulder main groove. The range of 80% to 90% is desirable.

  The pneumatic tire of the present invention includes a shoulder main groove extending in a zigzag shape including a first inclined portion and a second inclined portion inclined to the opposite side of the first inclined portion, and an inner portion connected to the first inclined portion. A shoulder lateral groove that is inclined in the same direction as the second inclined portion from the end and extends outward in the tire axial direction is provided. Such a shoulder main groove generates large traction in a muddy area by shearing mud compacted in the groove at the first inclined portion and the second inclined portion, and exhibits excellent mud performance. The shoulder cross groove also provides excellent mud performance.

  In general, at the position where the first inclined portion and the second inclined portion of the shoulder main groove intersect, the direction of the air flowing therein changes. For this reason, if the inner end of the shoulder lateral groove is connected to this position as in the prior art, much of the air flowing in the shoulder main groove flows into the shoulder lateral groove, generating a large outside noise (passing noise). easy. In the pneumatic tire of the present invention, the inner ends of the shoulder lateral grooves are connected so as to form a T-shaped three-way with the first inclined portion. For this reason, the inflow of air from the shoulder main groove to the shoulder lateral groove is suppressed during traveling. Therefore, the pneumatic tire of the present invention can reduce passing noise without reducing the groove volume of the shoulder main groove or the shoulder lateral groove while maintaining the mud performance.

It is an expanded view of the tread part of one Embodiment of this invention. It is an expanded sectional view of the AA cross section of FIG. It is the elements on larger scale near the crown lateral groove of FIG. FIG. 2 is a partially enlarged view of the vicinity of a shoulder main groove in FIG. 1. It is the perspective view to which the outer side zigzag top part vicinity of the shoulder lateral groove was expanded.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a development view of the tread portion 2 of the pneumatic tire of the present embodiment (hereinafter sometimes simply referred to as “tire”). The pneumatic tire of this embodiment can be suitably used for a four-wheel drive vehicle such as an SUV.

  As shown in FIG. 1, the tread portion 2 is provided with at least one shoulder main groove 3 on the most tread end Te side. In the present embodiment, a pair of shoulder main grooves 3 and 3 are provided on both sides of the tire equator C. Each shoulder main groove 3 extends in a zigzag shape continuously in the tire circumferential direction. The pair of shoulder main grooves 3 and 3 of the present embodiment have the same zigzag pitch P. The pair of shoulder main grooves 3 and 3 are arranged with the zigzag phases aligned with each other.

  The “tread end” is a position on the outermost side in the tire axial direction of the contact surface when a normal load is loaded on a normal tire and contacted with a flat surface with a camber angle of 0 °.

  The “normal state” is a no-load state in which a tire is assembled on a normal rim (not shown) and filled with a normal internal pressure. In this specification, unless otherwise specified, the dimensions of each part of the tire are values in a normal state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, For ETRTO, "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. For example, “maximum air pressure” for JATMA, “TIRE” for TRA The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. For example, “maximum load capacity” for JATMA, “table for TRA” The maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” in the case of ETRTO.

  The shoulder main groove 3 includes first inclined portions 4 and second inclined portions 5 alternately. The first inclined portion 4 is inclined to one side with respect to the tire circumferential direction. The second inclined portion 5 is inclined to the opposite side to the first inclined portion 4.

  A zigzag top portion 6 is formed between the first inclined portion 4 and the second inclined portion 5 that are adjacent to each other in the tire circumferential direction. The zigzag top portion 6 includes an outer zigzag top portion 6a that protrudes outward in the tire axial direction and an inner zigzag top portion 6b that protrudes inward in the tire axial direction.

  Such a zigzag shoulder main groove 3 shears mud compacted in the groove by the first inclined portion 4 and the second inclined portion 5. As a result, great traction is generated in the muddy area, and excellent mud performance is exhibited. In addition, the zigzag shoulder main groove 3 is less likely to generate air column resonance sound while traveling on a dry road surface, and thus can reduce passing noise. From these viewpoints, the first inclined portion 4 and the second inclined portion 5 are preferably inclined at an angle θ of, for example, 30 to 40 degrees with respect to the tire circumferential direction. Moreover, as for the 1st inclination part 4 and the 2nd inclination part 5, it is desirable to each extend linearly.

  The zigzag amplitude W1 of the shoulder main groove 3 is preferably in the range of 20% to 30% of the tread width TW, which is the distance between the tread ends Te, for example. When the zigzag amplitude W1 is less than 20% of the tread width TW, the traction generated by the first inclined portion 4 and the second inclined portion 5 may be reduced. On the contrary, when the zigzag amplitude W1 is larger than 30% of the tread width TW, it may be difficult to compress mud in the shoulder main groove 3. In any case, the traction generated by the first inclined portion 4 and the second inclined portion 5 is lowered, and the mud performance may not be sufficiently improved.

  The groove width WS of the shoulder main groove 3 is preferably in the range of 3% to 8% of the tread width TW, for example. When the groove width WS is less than 3% of the tread width TW, the mud pressed in the shoulder main groove 3 is reduced, and the traction generated by the first inclined portion 4 and the second inclined portion 5 may be reduced. On the other hand, when the groove width WS is larger than 8% of the tread width TW, it may be difficult to compress mud in the groove of the shoulder main groove 3. In these cases, the mud performance may not be sufficiently improved.

  In order to further improve the mud performance and reduce the passing noise, the groove width of the outer zigzag top 6a is preferably larger than the groove width of the inner zigzag top 6b.

  FIG. 2 shows an enlarged cross-sectional view in which a part of the A-A cross section in FIG. 1 is enlarged. As shown in FIG. 2, the groove depth D1 of the shoulder main groove 3 is preferably in the range of 4% to 9% of the tread width TW, for example, from the same viewpoint as the groove width WS.

  FIG. 3 shows an enlarged view of the vicinity of the tire equator C in FIG. As shown in FIG. 1 or FIG. 3, a crown land portion 8 is divided between the shoulder main grooves 3 and 3 in the tread portion 2. In the present embodiment, since the zigzag phases of the pair of shoulder main grooves 3 and 3 are aligned with each other, the crown land portion 8 extends zigzag in the tire circumferential direction while keeping the width in the tire axial direction constant. . The crown land portion 8 is provided with, for example, a plurality of crown lateral grooves 7. Thereby, the crown land portion 8 is divided into a plurality of crown blocks 8C.

  The crown lateral groove 7 extends between the shoulder main grooves 3 and 3. The crown lateral groove 7 of the present embodiment includes first crown lateral grooves 7a and second crown lateral grooves 7b that are alternately arranged in the tire circumferential direction. The first crown lateral groove 7 a is inclined in the same direction as the first inclined portion 4 of the crown main groove 3. The second crown lateral groove 7b is inclined in the same direction as the second inclined portion 5 of the crown main groove 3, that is, is inclined in the opposite direction to the first crown lateral groove 7a.

  The first crown lateral groove 7 a of the present embodiment connects the inner zigzag top portion 6 b of one shoulder main groove 3 and the second inclined portion 5 of the other shoulder main groove 3. Preferably, the first crown lateral groove 7a is connected to, for example, an intermediate portion in the longitudinal direction of the second inclined portion 5.

  The second crown lateral groove 7b of the present embodiment connects between the inner zigzag top portion 6b of the other shoulder main groove 3 and the first inclined portion 4 of the one shoulder main groove 3. Preferably, the second crown lateral groove 7b is connected to, for example, an intermediate portion of the first inclined portion 4 in the longitudinal direction.

  Such a crown lateral groove 7 can also generate a large traction and further improve the mud performance by shearing the mud compacted in the groove in the mud. From such a viewpoint, it is desirable that the crown lateral groove 7 is inclined at an angle α of, for example, 50 to 60 degrees with respect to the tire circumferential direction. Further, it is desirable that the first crown lateral groove 7a and the second crown lateral groove 7b each extend linearly.

  The crown block 8C preferably has a polygonal tread surface in order to increase the frictional force against the road surface by causing its edges to act in various directions. In this embodiment, the crown block 8C is divided into a substantially pentagonal shape. The crown block 8C of the present embodiment is provided with, for example, a sub-groove 12 extending from the crown lateral groove 7 and terminating in the crown block 8C in order to reduce the rigidity and improve the wear resistance. As a result, the tread surface of the crown block 8C is formed in a substantially C shape.

  The crown block 8C is preferably provided with a siping 13. The siping 13 extends in a substantially C shape so as to surround the sub-groove 12. The siping 13 is preferably a closed sipe that ends in the crown block 8C. Such a siping 13 is useful for improving the rigidity and durability of the crown block 8C in a well-balanced manner.

  FIG. 4 shows an enlarged view near the shoulder main groove 3 on the right side of FIG. As shown in FIG. 4, the shoulder land portion 11 is divided into the tread portion 2 of the present embodiment by the shoulder main groove 3 and the tread end Te. The shoulder land portion 11 is provided with a plurality of shoulder lateral grooves 9 to divide a plurality of shoulder blocks 11S.

  The shoulder lateral groove 9 is inclined in the same direction as the second inclined portion 5 from the inner end 9i connected to the first inclined portion 4 of the shoulder main groove 3, extends outward in the tire axial direction, and communicates with the tread end Te. . Further, the inner end 9i of the shoulder lateral groove 9 is connected to the first inclined portion 4 so as to form a T-shaped three-way.

  Generally, at the top position of the zigzag where the first inclined portion 4 and the second inclined portion 5 of the shoulder main groove 3 intersect, the direction of the air flowing therethrough changes, so that the inner end 9i of the shoulder lateral groove 9 is connected thereto. If so, there is a problem that air easily flows into the shoulder lateral groove 9 from the shoulder main groove 3 and the passing noise increases. However, the inner end 9i of the shoulder lateral groove 9 of the present embodiment is not at the position where the first inclined portion 4 and the second inclined portion 5 intersect, but forms the above-described first inclined portion 4 and a T-shaped three-way. It is connected to the. That is, the inner end 9i of the shoulder lateral groove 9 is provided so as to be displaced so as not to overlap with a region where the second inclined portion 5 is extended to the tread end Te side. Accordingly, the tire of the present embodiment is prevented from flowing into the shoulder lateral groove 9 from the shoulder main groove 3 while traveling on the dry road surface. Noise can be reduced.

  The inner end 9i of the shoulder lateral groove 9 extends, for example, the groove edge 5b on the inner side in the tire axial direction of the second inclined portion 5 to the tread grounding end Te side in the zigzag 1 pitch P of the shoulder main groove 3 including the outer zigzag top 6a. It is desirable to be located on the inner side in the tire axial direction than the imaginary line L. That is, it is desirable that the inner end 9 i of the shoulder lateral groove 9 is not opposed to the second inclined portion 5. According to such a shoulder lateral groove 9, the inflow of air from the shoulder main groove 3 to the shoulder lateral groove 9 is further suppressed during traveling on a dry road surface, and the passing noise can be further reduced.

  On the other hand, when the distance L1 between the inner end 9i of the shoulder lateral groove 9 and the virtual line L is too large, the mud performance tends to be lowered. For this reason, the distance L1 between the inner end 9i of the shoulder lateral groove 9 and the imaginary line L is preferably in the range of 4.0 mm or less, for example.

  As shown in FIG. 4, the shoulder lateral groove 9 of the present embodiment includes a first portion 15 extending outward from the inner end 9 i in the tire axial direction, and a second portion 16 having a groove width larger than the first portion. Yes.

  The first portion 15 of the shoulder lateral groove 9 is inclined at an angle β (shown in FIG. 1) of, for example, 30 to 40 degrees with respect to the tire circumferential direction in order to sufficiently exhibit the edge component and improve the mud performance. It is desirable.

  The first portion 15 has a groove width W3 perpendicular to the longitudinal direction, for example, in the range of 35% to 75% of the groove width WS of the shoulder main groove 3 in order to improve the mud performance and reduce the passing noise. Is desirable.

  As shown in FIG. 2, the groove depth D3 of the first portion 15 of the shoulder lateral groove 9 is, for example, 80% to 90% of the groove depth D1 of the shoulder main groove 3 from the same viewpoint as the groove width W3. A range is desirable.

  As shown in FIG. 4, the second portion 16 of the shoulder lateral groove 9 has a maximum value of the groove width W2 perpendicular to the longitudinal direction from the viewpoint of drainability to the outside in the tire axial direction, for example, the shoulder main groove 3. The groove width WS is desirably in the range of 120% to 200%. As shown in FIG. 2, the maximum value of the groove depth D2 of the second portion 16 of the shoulder lateral groove 9 is, for example, about the same as the groove depth D1 of the shoulder main groove 3 from the same viewpoint as the groove width W2. It is desirable.

  In the present embodiment, it is preferable that the following preferable aspect is further adopted for the shoulder main groove 3. The first inclined portion 4 of the shoulder main groove 3 includes an inner portion 4j on the inner zigzag top portion 6a side from the inner end 9i of the shoulder lateral groove 9, and an outer portion 4k on the outer zigzag top portion 6b side. Preferably, the groove width W4 of the outer portion 4k is larger than the groove width W5 of the inner portion 4j. The groove width W4 is more preferably in the range of 130% to 140% of the groove width W5, for example.

  The second inclined portion 5 of the shoulder main groove 3 includes an inner portion 5j on the inner zigzag top portion 6b side and an outer portion 5k on the outer zigzag top portion 6a side, with the vicinity of the center in the longitudinal direction as a boundary. In the second inclined portion 5 of the present embodiment, the groove width W6 of the outer portion 5k is preferably larger than the groove width W7 of the inner portion 5j. The groove width W6 is more preferably in the range of 130% to 140% of the groove width W7, for example. The inner portion 5j and the outer portion 5k of the present embodiment are formed, for example, by bending the groove edge 5a of the second inclined portion 5 near the center in the longitudinal direction of the second inclined portion 5.

  FIG. 5 shows a perspective view in which the vicinity of the outer zigzag top 6a of the shoulder main groove 3 is enlarged. As shown in FIG. 5, the outer zigzag top portion 6 a of the shoulder main groove 3 is preferably a groove edge 4 a on the outer side in the tire axial direction of the first inclined portion 4 and a groove edge on the outer side in the tire axial direction of the second inclined portion 5. 5a is linearly extended along the tire circumferential direction.

  The direction of flow of the air flowing in the shoulder main groove 3 is gradually changed by the groove edge 4 a of the first inclined portion 4, the outer zigzag top portion 6 a and the groove edge 5 a of the second inclined portion 5. For this reason, the direction of the air flowing through the shoulder main groove 3 is close to a right angle with respect to the inner end 9i of the shoulder lateral groove 9, and the inflow of air from the shoulder main groove 3 to the shoulder lateral groove 9 is further suppressed. .

  As shown in FIG. 1, the shoulder block 11S preferably has a polygonal tread surface from the same viewpoint as the crown block 8C. In this embodiment, the zigzag phase of the shoulder main groove 3 and the shoulder lateral groove 9 The second portion 16 is divided into a substantially Y shape.

  In the shoulder block 11S of the present embodiment, for example, a siping 10a extending from the shoulder main groove 3 or the shoulder lateral groove 9 is provided in order to reduce the rigidity. The siping 10a extends toward the center of the shoulder block 11S and terminates in the shoulder block 11S. The shoulder block 11S is preferably provided with a secondary groove 10b. The secondary groove 10b is connected, for example, between the terminal end of the siping 10a and the tread end Te. Such sub-grooves 10b are useful for further improving the drainage performance toward the outside in the tire axial direction.

  As mentioned above, although especially preferable embodiment of this invention was described in full detail, this invention is not limited to this embodiment, It can deform | transform and implement in a various aspect.

Tires (size: 225 / 95R16) having the basic pattern shown in FIG. 1 and based on the specifications of Table 1 were prototyped and their performance was tested. As a comparative example, a tire in which the shoulder lateral groove and the second inclined portion face each other with an overlap of the distance L1 was manufactured and tested in the same manner.
The test method is as follows.

<Passing noise>
Each sample tire is mounted on all the wheels of the test vehicle, and a straight test course is coasted at a passing speed of 60 km / H in accordance with the actual vehicle coasting test specified in JASO C606, and the vehicle runs at the midpoint of the course. The maximum passing sound level dB (A) was measured by an installation microphone installed at a position of height of 1.2 m from the test road surface with a distance of 7.5 m from the center line. The result is an index with the reciprocal of the comparative example being 100, and the larger the numerical value, the smaller the passing noise.

<Mad performance>
After running the test vehicle on a test course including a muddy area, the traction performance in the muddy area was evaluated by the driver's sensuality. A result is a score which sets the comparative example as 100, and it is excellent in mud performance, so that a numerical value is large.

  As shown in Table 1, it was confirmed that the tires of each example can reduce the passing noise while maintaining the mud performance.

2 tread portion 3 shoulder main groove 4 first inclined portion 5 second inclined portion 7S shoulder lateral groove 7a inner end Te tread end C tire equator

Claims (7)

A pneumatic tire in which a tread portion is provided with at least one shoulder main groove extending continuously from the shoulder main groove in the tire circumferential direction and a plurality of shoulder lateral grooves extending from the shoulder main groove to the tread end. ,
The shoulder main groove extends in a zigzag shape including a first inclined portion and a second inclined portion inclined to the opposite side of the first inclined portion,
The shoulder main groove includes an outer zigzag top portion that protrudes outward in the tire axial direction, and an inner zigzag top portion that protrudes inward in the tire axial direction,
The shoulder lateral groove is inclined in the same direction as the second inclined portion from the inner end connected to the first inclined portion and extends outward in the tire axial direction.
The inner end of the shoulder lateral groove is connected to form a T-shaped three-way with the first inclined portion ,
The first inclined portion includes an inner portion on the inner zigzag top side from the inner end of the shoulder lateral groove, and an outer portion on the outer zigzag top portion side from the inner end of the shoulder lateral groove,
The pneumatic tire according to claim 1, wherein a groove width of the outer portion is larger than a groove width of the inner portion . In the zigzag one pitch of the shoulder main groove before including Kisotogawa zigzag top, the inner end of the shoulder lateral grooves, the virtual line obtained by extending the axially inner groove edge of the second inclined portion to the tread ground contact edge side The pneumatic tire according to claim 1, which is located on the inner side in the tire axial direction.   The pneumatic tire according to claim 2, wherein a distance between the inner end of the shoulder lateral groove and the imaginary line is in a range of 4.0 mm or less. The pneumatic tire according to any one of claims 1 to 3 , wherein the outer zigzag top of the shoulder main groove extends linearly along the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 4, wherein the first inclined portion and the second inclined portion are inclined at an angle of 30 to 40 degrees with respect to a tire circumferential direction. The pneumatic tire according to any one of claims 1 to 5, wherein at least an inner portion of the shoulder lateral groove in the tire axial direction is inclined at an angle of 30 to 40 degrees with respect to a tire circumferential direction. The shoulder lateral groove includes a first portion extending outward in the tire axial direction from the inner end,
The pneumatic tire according to any one of claims 1 to 6, wherein a groove depth of the first portion is in a range of 80% to 90% of a groove depth of the shoulder main groove.

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