JP6002190B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that achieves both noise performance and mud performance.

  Patent Document 1 below proposes a pneumatic tire for running on rough terrain having a main groove extending in a zigzag shape in the tire circumferential direction and a shoulder lateral groove extending from the main groove to the tread grounding end side. Such a tire generates a large grip force when traveling in a muddy area, especially because each groove shears a large amount of mud (hereinafter, the muddy performance is referred to as “mad performance”). is there.).

  However, the tire of Patent Document 1 has a tendency to generate a large pumping sound because a large amount of air passes through the shoulder lateral groove when traveling on a paved road surface.

JP-A-5-278415

  The present invention has been devised in view of the actual situation as described above, and has as its main object to provide a pneumatic tire that achieves both mud performance and noise performance.

In the tread portion, a shoulder main groove extending in a zigzag shape continuously on the tread ground end side in the tire circumferential direction and a plurality of shoulder lateral grooves extending outward in the tire axial direction from the shoulder main groove are provided in the tread portion. In each of the pneumatic tires, each shoulder lateral groove includes a first lateral groove portion continuous with the shoulder main groove, and a tire width in the tire axial direction of the first lateral groove portion, and a groove width and a groove larger than the first lateral groove portion. A groove wall on one side in the tire circumferential direction of the second lateral groove portion and a groove wall on one side in the tire circumferential direction of the first lateral groove portion, which is smoothly continuous with the second lateral groove portion having a depth , The groove wall on the other side in the tire circumferential direction of the second lateral groove portion extends from the groove wall on the other side in the tire circumferential direction of the first lateral groove portion in a direction to increase the width of the shoulder lateral groove in a stepped manner. and characterized in that it comprises a To have.

  In the pneumatic tire of the present invention, the shoulder main groove includes a first inclined portion inclined with respect to a tire circumferential direction, and a second inclined portion inclined in a direction opposite to the first inclined portion, It is desirable that the one lateral groove portion communicates with the first inclined portion and is inclined in the same direction as the second inclined portion.

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

  In the pneumatic tire of the present invention, the first inclined portion includes a narrow portion, and a wide portion that is continuous with the outer side in the tire axial direction of the narrow portion and has a larger groove width than the narrow portion, It is desirable that the first lateral groove portion communicates with the wide portion.

  In the pneumatic tire according to the present invention, a narrow shoulder lateral groove extending along the shoulder lateral groove and having a groove width smaller than the first lateral groove portion is provided between the shoulder lateral grooves adjacent to each other in the tire circumferential direction. It is desirable that

In the pneumatic tire of the present invention, a shoulder land portion is divided outside the shoulder main groove in the tire axial direction, and the shoulder land portion is provided with a shoulder sipe on the inner side in the tire axial direction than the shoulder narrow lateral groove, The shoulder sipe preferably includes a first shoulder sipe continuous with the first lateral groove portion, a second shoulder sipe continuous with the shoulder main groove, and a third shoulder sipe continuous with the shoulder narrow lateral groove. Further, in the pneumatic tire of the present invention, the shoulder main groove includes a first inclined portion that is inclined with respect to a tire circumferential direction, and a second inclined portion that is inclined in a direction opposite to the first inclined portion, The first inclined portion and the second inclined portion each include a narrow portion and a wide portion having a groove width larger than the narrow portion, and the narrow portion and the first portion of the first inclined portion. The narrow portion of the two inclined portions is connected to each other on the inner side in the tire axial direction of the shoulder main groove, and the wide portion of the first inclined portion and the wide portion of the second inclined portion are the shoulder main groove. It is desirable that they are continuous with each other on the outer side in the tire axial direction.

  The pneumatic tire according to the present invention has a shoulder main groove extending in a zigzag manner continuously in the tire circumferential direction at the tread portion, and a plurality of shoulder lateral grooves extending outward from the shoulder main groove in the tire axial direction. Is provided. Such a pneumatic tire guides a large amount of mud into the shoulder main groove and the shoulder lateral groove, and generates a large reaction force when each groove shears the mud. Therefore, excellent mud performance can be obtained.

  The shoulder lateral groove includes a first lateral groove portion that is continuous with the shoulder main groove, and a second lateral groove portion that is continuous with the outer side in the tire axial direction of the first lateral groove portion and has a larger groove width and groove depth than the first lateral groove portion. Yes. One groove wall of the first transverse groove portion is smoothly continuous with the groove wall of the second transverse groove portion.

  In such a shoulder lateral groove, the amount of air flowing from the shoulder main groove to the second lateral groove portion side is restricted by the first lateral groove portion, and the pumping sound can be reduced. And since one groove wall of the 1st horizontal groove part is smoothly continuing with the groove wall of the 2nd horizontal groove part, the air which flowed in from the shoulder main groove does not generate a turbulent flow in a shoulder horizontal groove, It is smoothly discharged to the tread grounding end side along the groove walls of the continuous first and second lateral groove portions. For this reason, the instantaneous increase in the air pressure in the shoulder lateral groove when the tread portion is grounded is mitigated, and the pumping noise is further suppressed.

  As described above, the pneumatic tire of the present invention can balance both mud performance and noise performance with a good balance.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. It is an enlarged view of the shoulder land part of FIG. It is the sectional view on the AA line of the 1st horizontal groove part and 2nd horizontal groove part of FIG. It is an enlarged view of the center land part of FIG. It is an expanded view of the tread part of the pneumatic tire of a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a development view of a tread portion 2 of a pneumatic tire (hereinafter, also simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire 1 of this embodiment is suitably used for, for example, an SUV suitable for running on rough terrain.

  As shown in FIG. 1, the tread portion 2 of the tire 1 is provided with a pair of shoulder main grooves 3 and 3.

  Each shoulder main groove 3 extends zigzag continuously in the tire circumferential direction on the tread ground contact end Te side.

  The “tread grounding end Te” is a flat surface with a normal load applied to a normal tire 1 which is assembled with a normal rim (not shown) and filled with a normal internal pressure, and which is not loaded, with a camber angle of 0 °. This is the contact position on the outermost side in the tire axial direction when the contact is made on the ground.

  The “regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, “standard rim” for JATMA and “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. “JAMATA” is the “highest air pressure”, TRA is the table “TIRE LOAD LIMITS AT” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for 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. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The shoulder main groove 3 includes, for example, a first inclined portion 5 that is inclined with respect to the tire circumferential direction and a second inclined portion 6 that is inclined in a direction opposite to the first inclined portion 5. The first inclined portions 5 and the second inclined portions 6 are provided alternately in the tire circumferential direction. The first inclined portion 5 and the second inclined portion 6 have, for example, the same length in the tire circumferential direction.

  The first inclined portion 5 includes, for example, a narrow portion 5a and a wide portion 5b that is continuous with the outer side in the tire axial direction of the narrow portion 5a and has a larger groove width than the narrow portion 5a. Similarly to the first inclined portion 5, the second inclined portion 6 includes a narrow portion 6 a and a wide portion 6 b that is connected to the outer side in the tire axial direction of the narrow portion 6 a and has a larger groove width than the narrow portion 6 a. Contains.

  The narrow portion 5a of the first inclined portion 5 and the narrow portion 6a of the second inclined portion 6 are connected to each other inside the shoulder main groove 3 in the tire axial direction. The wide portion 5b of the first inclined portion 5 and the wide portion 6b of the second inclined portion 6 are connected to each other outside the shoulder main groove 3 in the tire axial direction.

  The narrow portions 5a and 6a and the wide portions 5b and 6b increase the volume of the shoulder main groove 3 while maintaining the rubber volume on the tire equator C side. For this reason, the steering stability on the dry road surface and the mud performance are improved in a well-balanced manner.

  In order to further exert the above-described effects, the ratio W7 / W8 of the groove width W7 of the narrow portions 5a, 6a and the groove width W8 of the wide portions 5b, 6b is preferably 0.65 or more, more preferably 0.8. It is 70 or more, preferably 0.80 or less, more preferably 0.75 or less.

  The angle θ1 of the first inclined portion 5 and the second inclined portion 6 with respect to the tire circumferential direction is, for example, 10 to 45 °, and more preferably 30 to 40 °. In such shoulder main grooves 3, the groove edges increase the frictional force in the tire circumferential direction and the tire axial direction with a good balance.

  The groove width W1 of the shoulder main groove 3 is, for example, 3.0 to 8.0% of the tread ground contact width TW. Such a shoulder main groove 3 enhances the steering stability on the dry road surface and the mud performance with a good balance. The tread contact width TW is a distance in the tire axial direction between the tread contact ends Te and Te of the tire 1 in the normal state.

  In the case of an SUV tire, the depth of the shoulder main groove 3 is preferably 8 to 15 mm, for example.

  In order to improve the mud performance while maintaining the rigidity of the tread portion 2, the distance L1 in the tire axial direction from the tire equator C to the center line 3c of the shoulder main groove 3 is, for example, 5 to 20% of the tread ground contact width TW. It is desirable to increase or decrease in the tire circumferential direction in the range of.

  The tread portion 2 is divided into a shoulder land portion 12 on the outer side in the tire axial direction of the shoulder main groove 3 and a center land portion 13 between the pair of shoulder main grooves 3 and 3.

  FIG. 2 shows an enlarged view of the shoulder land portion 12. As shown in FIG. 2, the shoulder land portion 12 is provided with a plurality of shoulder lateral grooves 15 extending outward from the shoulder main groove 3 in the tire axial direction.

  For example, the shoulder lateral groove 15 extends from the shoulder main groove 3 to at least the tread grounding end Te. Such shoulder lateral groove 15 effectively drains the water in the shoulder main groove 3 during wet running.

  The shoulder lateral groove 15 includes a first lateral groove portion 17 that continues to the shoulder main groove 3 and a second lateral groove portion 18 that continues to the outer side in the tire axial direction of the first lateral groove portion 17.

  For example, the first lateral groove portion 17 is connected to a position excluding a top portion that protrudes in the tire axial direction of the shoulder main groove 3, and is connected to the first inclined portion 5 in the present embodiment. As a desirable mode, the first lateral groove portion 17 continues to the wide portion 5 b of the first inclined portion 5. Since the air pressure in the groove is reduced in the wide portion 5b, such a first lateral groove portion 17 is useful for reducing the pumping sound of the shoulder lateral groove 15.

  For example, the first lateral groove portion 17 is inclined in the same direction as the second inclined portion 6 of the shoulder main groove 3. The first lateral groove portion 17 of the present embodiment extends linearly along the second inclined portion 6. Such a first lateral groove portion 17 uses, for example, inertia when water in the second inclined portion 6 moves to the first inclined portion 5 side during wet traveling, so that the water is brought to the tread grounding end Te side. invite.

  The groove width W2 of the first lateral groove portion 17 is, for example, 4.0 to 8.0 mm, and preferably 5.0 to 7.0 mm. The groove width W2 of the first lateral groove portion 17 of the present embodiment is substantially constant in the groove length direction. The groove depth of the first lateral groove portion 17 is, for example, 6.0 to 9.0 mm.

  For example, the second lateral groove portion 18 extends in the tire axial direction from the first lateral groove portion 17 to the tread grounding end Te. An angle θ2 of the second lateral groove portion 18 with respect to the tire axial direction is, for example, 0 to 30 °. As a desirable mode, the angle θ2 of the second lateral groove portion 18 gradually decreases toward the outer side in the tire axial direction, for example.

  The second lateral groove portion 18 has a larger groove width than the first lateral groove portion 17. The groove width W3 at the tread grounding end Te of the second lateral groove portion 18 is preferably, for example, 3.5 to 6.0 times the groove width W2 of the first lateral groove portion 17, and more preferably 4.5 to 5.0. Is double.

  As a desirable aspect, the second lateral groove portion 18 includes a first portion 21 whose groove width gradually increases toward the outer side in the tire axial direction, and is connected to the outer side in the tire axial direction of the first portion 21, and has a substantially constant groove width in the tire axial direction. And a second portion 22 extending outward. Such a second lateral groove portion 18 is useful for improving wet performance and mud performance while maintaining the rigidity of the tread portion 2 on the tire equator C side.

  FIG. 3 is a cross-sectional view taken along line AA of the first lateral groove portion 17 and the second lateral groove portion 18 in FIG. As shown in FIG. 3, the second lateral groove portion 18 has a larger groove depth d <b> 2 than the first lateral groove portion 17. The groove depth d2 of the second lateral groove portion 18 is preferably 1.25 to 1.65 times, more preferably 1.45 to 1.50 times the groove depth d1 of the first lateral groove portion 17.

  In the first lateral groove portion 17 and the second lateral groove portion 18, the amount of air flowing from the shoulder main groove 3 to the second lateral groove portion 18 side is restricted by the first lateral groove portion 17, thereby reducing the pumping sound. Can do.

  As shown in FIG. 2, the groove wall 26 on one side in the tire circumferential direction of the second lateral groove portion 18 (upper side in FIG. 2) smoothly continues to the groove wall 24 on the one side of the first lateral groove portion 17. ing.

  As a result, the air flowing in from the shoulder main groove 3 does not generate turbulent flow in the shoulder lateral groove 15, and smoothly flows along the groove walls of the first lateral groove portion 17 and the second lateral groove portion 18 that are continuous. It is discharged to the Te side. For this reason, the momentary increase in the air pressure in the shoulder lateral groove 15 when the tread portion 2 is grounded is mitigated, and the pumping noise is further suppressed.

  The groove wall 27 on the other side (the lower side in FIG. 2) of the second lateral groove portion 18 in the tire circumferential direction is, for example, a groove width of the shoulder lateral groove 15 stepwise from the groove wall 25 on the other side of the first lateral groove portion 17. It extends in the direction to enlarge.

  The shoulder land portion 12 is divided into a plurality of shoulder blocks 30 by providing a plurality of the shoulder lateral grooves 15 described above.

  The shoulder block 30 is provided with a shoulder narrow lateral groove 32 and a shoulder sipe 33, for example. In this specification, “sipe” means a cut having a width of about 0.5 to 1.5 mm, and is distinguished from a drainage groove.

  The shoulder narrow lateral groove 32 is provided, for example, between the second lateral groove portions 18 and 18 adjacent to each other in the tire circumferential direction, and extends along the second lateral groove portion 18. Such shoulder narrow lateral grooves 32 exhibit excellent mud performance while suppressing chipping and uneven wear of the shoulder block 30.

  The shoulder narrow lateral groove 32 has, for example, a groove width W5 smaller than the first lateral groove portion 17 of the shoulder main groove 3. The groove width W5 of the shoulder narrow lateral groove 32 is preferably 0.60 times or more, more preferably 0.65 times or more, preferably 0.75 times or less, more preferably, the groove width W2 of the first lateral groove portion 17. 0.70 times or less. Such a shoulder narrow lateral groove 32 enhances steering stability and mud performance on a dry road surface in a well-balanced manner.

  The shoulder sipe 33 is provided, for example, on the inner side in the tire axial direction of the shoulder narrow lateral groove 32.

  The shoulder sipe 33 includes, for example, a first shoulder sipe 36 that is continuous with the first lateral groove portion 17, a second shoulder sipe 37 that is continuous with the shoulder main groove 3, and a third shoulder sipe 38 that is continuous with the shoulder narrow lateral groove 32. . Such a shoulder sipe 33 has edge components extending in multiple directions, and enhances the grip force on relatively hard rough terrain.

  For example, the first shoulder sipe 36 is continuous with the first lateral groove portion 17 at an angle θ3 of 75 to 90 °. For example, the first shoulder sipe 36 extends from the first lateral groove portion 17 along the first inclined portion 5 of the shoulder main groove 3 and terminates in the shoulder block 30.

  For example, the second shoulder sipe 37 is connected to the wide portion 6 b of the second inclined portion 6 of the shoulder main groove 3. For example, the second shoulder sipe 37 extends along the first inclined portion 5 of the shoulder main groove 3.

  The third shoulder sipe 38 extends from the inner end 32 i of the shoulder narrow lateral groove 32 in the tire axial direction along the first inclined portion 5 of the shoulder main groove 3.

  The third shoulder sipe 38 terminates in the shoulder block 30, for example. The 3rd shoulder sipe 38 is not limited to such an aspect, For example, you may communicate with the 1st shoulder sipe 36. FIG.

  As a desirable mode, the 3rd shoulder sipe 38 and the 2nd shoulder sipe 37 are mutually connected in T shape, for example. Such third shoulder sipes 38 and second shoulder sipes 37 guide the air in the shoulder main groove 3 toward the shoulder narrow lateral groove 32 and serve to suppress the pumping sound of the shoulder main groove 3.

  FIG. 4 shows an enlarged view of the center land portion 13. As shown in FIG. 4, the center land portion 13 is provided with a plurality of center lateral grooves 41 communicating between the shoulder main grooves 3, 3, thereby dividing a plurality of center blocks 42.

  The center lateral groove 41 includes, for example, a first center lateral groove 44 that is inclined with respect to the tire axial direction, and a second center lateral groove 45 that is inclined in the direction opposite to the first center lateral groove 44. The first center lateral grooves 44 and the second center lateral grooves 45 are provided alternately in the tire circumferential direction, for example. Such a center lateral groove 41 can effectively guide water between the road surface and the center land portion 13 to the shoulder main grooves 3 on both sides when the center land portion 13 contacts the wet road surface.

  In order to further enhance the above-described effects, the angle θ5 of the center lateral groove 41 with respect to the tire axial direction is preferably 20 ° or more, more preferably 25 ° or more, preferably 35 ° or less, more preferably 30 ° or less. .

  The center lateral groove 41 has a groove width W6 smaller than the shoulder main groove 3, for example. The groove width W6 of the center lateral groove 41 is, for example, 0.3 to 0.5 times the groove width W1 of the shoulder main groove 3. Such a center lateral groove 41 improves steering stability and wet performance on a dry road surface in a well-balanced manner.

  The center block 42 includes, for example, an edge 47 on the side of the center lateral groove 41 and a center recess 50 in which a wall extending from the edge 47 inward in the tire radial direction is recessed, and a plurality of center sipes 51 having both ends terminating in the center block 42. have. For example, when the center concave portion 50 and the center sipe 51 are filled, the center block 42 has a substantially pentagonal tread surface.

  As for the center recessed part 50, it is desirable for the width | variety of the direction along the center horizontal groove 41 to reduce gradually toward the inside of a block, for example. Such a center recess 50 compresses mud inside and improves mud performance when traveling in a muddy area.

  The center sipe 51 includes, for example, a first center sipe 53 that extends linearly and a second center sipe 54 that bends in the middle.

  For example, the first center sipe 53 extends along the first center lateral groove 44 or the second center lateral groove 45.

  The second center sipe 54 has, for example, a first portion 56 extending along the first inclined portion 5 of the shoulder main groove 3 and a second portion 57 extending along the second inclined portion 6 of the shoulder main groove 3. doing.

  The first center sipe 53 and the second center sipe 54 as described above increase the edge component while maintaining the rigidity of the center block 42. For this reason, the wear resistance and mud performance of the center block 42 are improved.

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

A size 225 / 95R16 pneumatic tire for SUV having the basic pattern of FIG. As a comparative example, as shown in FIG. 5, the first lateral groove portion and the second lateral groove portion of the shoulder main groove have the same groove depth, and the groove walls on both sides of the second lateral groove portion, A tire connected to the groove wall of the first lateral groove portion in a step shape was prototyped. Each test tire was tested for mud performance and noise performance. The common specifications and test methods for each test tire are as follows.
Wearing rim: 16 x 5.5
Tire internal pressure: 220kPa
Test vehicle: displacement 3600cc, four-wheel drive vehicle Tire mounting position: all wheels

<Mad performance>
The driving performance of the test vehicle on the test course including the muddy area was evaluated by the driver's sensuality. A result is a score which makes a comparative example 100, and shows that mud performance is excellent, so that a numerical value is large.

<Noise performance>
The in-vehicle noise when traveling on the road noise measuring road (asphalt rough road) at a speed of 100 km / h with the test vehicle was measured under the following conditions. The evaluation is the reciprocal of the value of the vehicle interior noise, and is represented by an index with the value of the comparative example being 100. The larger the value, the lower the vehicle interior noise and the better.
Measurement method: Measure the sound pressure level of the peak value of noise near 240 Hz with a microphone. Microphone position: Table 1 shows the test results for the driver's seat window side ear test.

  As can be seen from Table 1, it was confirmed that the pneumatic tires of the Examples achieved both good balance between mud performance and noise performance.

2 Tread portion 3 Shoulder main groove 15 Shoulder lateral groove 17 First lateral groove portion 18 Second lateral groove portion

Claims (7)

A pneumatic tire in which a tread portion is provided with a shoulder main groove extending in a zigzag manner continuously on the tread ground end side in the tire circumferential direction and a plurality of shoulder lateral grooves extending outward from the shoulder main groove in the tire axial direction. There,
Each of the shoulder lateral grooves includes a first lateral groove portion that is continuous with the shoulder main groove, and a second lateral groove that is continuous with the outer side in the tire axial direction of the first lateral groove portion and has a larger groove width and depth than the first lateral groove portion. Including
The groove wall on one side in the tire circumferential direction of the second lateral groove portion is smoothly continuous with the groove wall on one side in the tire circumferential direction of the first lateral groove portion,
The groove wall on the other side in the tire circumferential direction of the second lateral groove portion extends from the groove wall on the other side in the tire circumferential direction of the first lateral groove portion in a direction to increase the width of the shoulder lateral groove in a stepped manner. A pneumatic tire characterized by including . The shoulder main groove includes a first inclined portion that is inclined with respect to a tire circumferential direction, and a second inclined portion that is inclined in a direction opposite to the first inclined portion,
The pneumatic tire according to claim 1, wherein the first lateral groove portion communicates with the first inclined portion and is inclined in the same direction as the second inclined portion.   The pneumatic tire according to claim 2, wherein an angle of the first inclined portion and the second inclined portion with respect to a tire circumferential direction is 30 to 40 °. The first inclined portion includes a narrow portion, and a wide portion that continues to the tire axial direction outside of the narrow portion and has a larger groove width than the narrow portion,
The pneumatic tire according to claim 2 or 3, wherein the first lateral groove portion communicates with the wide portion.   5. The shoulder narrow lateral groove extending along the shoulder lateral groove and having a smaller groove width than the first lateral groove portion is provided between the shoulder lateral grooves adjacent to each other in the tire circumferential direction. The pneumatic tire according to any one of the above. A shoulder land portion is divided outside the shoulder main groove in the tire axial direction,
The shoulder land portion is provided with a shoulder sipe on the inner side in the tire axial direction than the shoulder narrow lateral groove,
The shoulder sipe includes a first shoulder sipe continuous with the first lateral groove portion, a second shoulder sipe continuous with the shoulder main groove, and a third shoulder sipe continuous with the shoulder narrow lateral groove. Pneumatic tire. The shoulder main groove includes a first inclined portion that is inclined with respect to a tire circumferential direction, and a second inclined portion that is inclined in a direction opposite to the first inclined portion,
Each of the first inclined part and the second inclined part includes a narrow part and a wide part having a groove width larger than the narrow part,
The narrow portion of the first inclined portion and the narrow portion of the second inclined portion are connected to each other on the inner side in the tire axial direction of the shoulder main groove,
The pneumatic tire according to any one of claims 1 to 6, wherein the wide portion of the first inclined portion and the wide portion of the second inclined portion are connected to each other on the outer side in the tire axial direction of the shoulder main groove. .

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