JP5749970B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire with improved noise performance while suppressing a decrease in steering stability performance.

  A pneumatic tire having a block pattern in which a plurality of blocks divided in a tread portion by a main groove extending in the tire circumferential direction and a lateral groove extending in a direction crossing the main groove is arranged in the tire circumferential direction is known.

  However, in the pneumatic tire having the above-described block pattern, since the block vibrates due to a large impact from the road surface at the time of ground contact, the noise performance is difficult. Further, as shown in FIG. 5, the tire circumferential direction end b1 of the block b rises from the road surface r due to a large force in the tire circumferential direction such as traction T, and as a result, the ground contact area s decreases and the steering stability performance. There were difficulties.

JP 2000-158915 A

  The present invention has been devised in view of the above-described problems, and forms radial ribs on the axial wall surface of the block and circumferential ribs on the circumferential wall surface, and defines these angles and the like. The main purpose is to provide a pneumatic tire with improved noise performance while suppressing deterioration in steering stability performance.

According to the first aspect of the present invention, the main tread portion is provided with a main groove extending continuously in the tire circumferential direction and a plurality of lateral grooves extending in a direction intersecting with the main groove. A pneumatic tire in which a block row in which blocks divided by a groove and the lateral groove are arranged in a tire circumferential direction is formed, wherein the lateral groove has an angle of 80 degrees or more with respect to the tire circumferential direction, An axial wall surface facing the transverse groove and a circumferential wall surface facing the main groove, and the axial wall surface has a groove depth direction at an angle of 30 degrees or less with respect to the normal direction of the block tread surface. A plurality of radial ribs extending in the length direction of the transverse groove are provided, while the circumferential rib extends in the length direction of the main groove at an angle of 10 degrees or less with respect to the block tread surface. There are a plurality of spaced in the groove depth direction, the half The directional rib includes an outer radial rib provided on both sides of the block in the tire axial direction, and an intermediate radial rib provided between the outer radial ribs, and the protrusion of the intermediate radial rib. The width is larger than the protruding width of the outer radial rib .

The invention according to claim 2 is the pneumatic tire according to claim 1 , wherein the protruding width of the intermediate radial rib is 150% to 200% of the protruding width of the outer radial rib .

According to a third aspect of the present invention, the circumferential rib is provided in a tread side region on the outer side in the tire radial direction from a position spaced 10% of the groove depth of the main groove from the groove bottom of the main groove. The pneumatic tire according to 1 or 2. The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the circumferential rib has a protruding width that gradually increases from a groove bottom of the main groove toward a tread surface. . The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein both ends of the circumferential rib of the circumferential rib terminate without contacting both ends of the circumferential wall surface in the tire circumferential direction. It is a pneumatic tire.

  In the pneumatic tire of the present invention, a main groove extending continuously in the tire circumferential direction and a plurality of horizontal grooves extending in a direction crossing the main groove are provided, whereby the main groove and the horizontal groove are separated. A block row in which the blocks are arranged in the tire circumferential direction is formed. The lateral groove is formed with an angle of 80 degrees or more with respect to the tire circumferential direction. Such a block increases lateral rigidity and exhibits a great edge effect in the tire axial direction. Therefore, the pneumatic tire of the present invention has improved steering stability performance and traction.

  The block has an axial wall surface facing the lateral groove and a circumferential wall surface facing the main groove, and the axial wall surface has an angle of 30 degrees or less with respect to the normal direction of the block tread surface. A plurality of radial ribs extending in the groove depth direction are provided in the transverse direction of the transverse groove. Such radial ribs improve the noise performance by disturbing and reducing the vibration of air passing through the transverse grooves.

  A plurality of circumferential ribs extending in the length direction of the main groove at an angle of 10 degrees or less with respect to the block tread surface are provided on the circumferential wall surface in the groove depth direction. Such circumferential ribs reinforce the block in cooperation with the radial ribs to increase the rigidity, and thus prevent the block from being lifted against bending deformation caused by traction or the like. Therefore, the pneumatic tire of the present invention secures a contact area and further improves the steering stability performance.

(A) is a development view of a tread portion of a pneumatic tire according to an embodiment of the present invention, and (b) is a cross-sectional view cut in a direction perpendicular to the longitudinal direction of the rib of (a) the present embodiment. . It is a perspective view of the block of this embodiment. (A) thru | or (c) is a figure which shows the other Example of a rib. (A) is a perspective view of a block according to another embodiment of the present invention, and (b) is a perspective view of a block according to still another embodiment of the present invention. It is a side view explaining the floating of the block at the time of driving | running | working.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1A, the pneumatic tire of the present embodiment (hereinafter sometimes simply referred to as “tire”) is suitably used as a tire for passenger cars, for example. A main groove 3 extending continuously in the tire circumferential direction and a plurality of lateral grooves 4 extending in a direction crossing the main groove 3 are provided. In the present embodiment, the main groove 3 is composed of a pair of center main grooves 3A extending continuously on both sides of the tire equator C in the tire circumferential direction. Further, the lateral groove 4 of the present embodiment includes a plurality of center lateral grooves 4A that connect between the center main grooves 3 and 3, and a plurality of shoulder lateral grooves 4B that connect between the center main groove 3 and the ground contact Te. Become.

  Thereby, in the tread portion 2, a center block row 5A1 in which a plurality of center blocks 5A divided by the two center main grooves 3A and the center lateral grooves 4A are arranged in the tire circumferential direction, the center main grooves 3A, and the shoulder lateral grooves 4B. A shoulder block row 5B1 is arranged in which a plurality of shoulder blocks 5B divided by the above are arranged in the tire circumferential direction. The tread portion 2 of the present invention is not limited to such an aspect, for example, a center block row, an aspect in which ribs are arranged on both sides in the tire axial direction, a rib on the tire equator, Various modes such as a mode in which shoulder block rows are arranged on both sides in the tire axial direction can be adopted.

  Here, the “grounding end” Te is grounded on a flat surface at a camber angle of 0 degree by applying a normal load to the tire 1 in a normal state in which a normal rim is assembled with a normal rim and filled with a normal internal pressure. It is determined as the contact position on the outermost side in the tire axial direction. The distance in the tire axial direction between the ground contact Te and Te is determined as the ground contact width TW. Further, the dimensions and the like of each part of the tire are values in the normal state unless otherwise specified.

  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 and “Design Rim” for TRA. For ETRTO, use "Measuring Rim".

  The “regular internal pressure” is the air pressure defined by each standard for each tire in the standard system including the standard on which the tire is based, and is “maximum air pressure” for JATMA and table for TRA. The maximum value described in TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES is "INFLATION PRESSURE" for ETRTO, but 180 kPa for tires for passenger cars.

  Furthermore, “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. “Maximum load capacity” for JATMA, “TIRE” for TRA The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is “LOAD CAPACITY” if it is ETRTO, but if the tire is for a passenger car, the load is equivalent to 88% of the above load.

  The main groove 3 has a linear shape along the tire circumferential direction. Since the main groove 3 suppresses unstable behavior such as vehicle wobbling and single flow during braking, it can exhibit excellent straight running stability. In addition, the main groove 3 is not limited to such an aspect, For example, it can change into various shapes, such as a wave shape and a zigzag shape.

  Further, the lateral groove 4 needs to be formed with an angle α1 with respect to the tire circumferential direction of 80 degrees or more. The block 5 in which the lateral groove 4 is formed has a large lateral rigidity and a great edge effect in the tire axial direction. Therefore, in the tire of the present invention, traction is enhanced and steering stability performance is improved.

  When the angle α1 is less than 80 degrees, the block 5 cannot cope with a large lateral force when turning, and the steering stability performance deteriorates. For this reason, the angle α1 is more preferably 85 degrees or more. The lateral groove 4 of the present embodiment is formed such that the angle α1 is 90 degrees.

  Further, the groove widths of the main grooves 3 and the lateral grooves 4 (the groove width perpendicular to the longitudinal direction of the grooves, hereinafter the same applies to other grooves) W1, W2 and the groove depth D1 (see FIG. 2). ) And D2 (not shown) can be variously determined in accordance with common practice. However, if the groove widths W1 and W2 and / or the groove depths D1 and D2 are too large, the rigidity of each block row may be lowered. If the groove widths are too small, the drainage performance may be lowered. For this reason, the groove width W1 of the main groove 3 is desirably 6 to 12% of the grounding width TW, for example, and the groove width W2 of the lateral groove 4 is desirably 3 to 6% of the grounding width TW, for example. The groove depth D1 of the main groove 3 is desirably 6 to 13 mm, and the groove depth D2 of the lateral groove 4 is desirably 3 to 10 mm. The groove depth of the main groove 3 and the lateral groove 4 of this embodiment is equal.

  Further, as shown in FIG. 2, the block 5 includes an axial wall surface 6 facing the lateral groove 4, a circumferential wall surface 7 facing the main groove 3, and a grounding surface connected to the radially outer edge thereof. Block tread 2A. Since the block 5 of this embodiment is formed in a substantially rectangular parallelepiped shape by the main groove 3 and the lateral groove 4 which form a straight line, the axial wall surface 6 and the circumferential wall surface 7 have a rectangular shape. The axial wall surface 6 and the circumferential wall surface 7 are not limited to such shapes, and various shapes such as a trapezoidal shape and a parallelogram shape can be adopted.

  In the present invention, a plurality of radial ribs 8 extending in the depth direction of the lateral grooves 4 are provided on the axial wall surface 6 in the length direction of the lateral grooves 4. Such radial ribs 8 disturb and reduce the vibrations of the air passing through the lateral grooves 4, thus improving the noise performance. Further, the axial wall surface 6 provided with the radial ribs 8 has a greater rigidity in the tire circumferential direction than the wall surface formed by the conventional flat surface. It helps prevent the ground from lifting and improves steering stability.

  Further, the radial rib 8 needs to be formed at an angle θ1 of 30 degrees or less with respect to the normal n direction of the tread surface 2A. That is, when the angle θ1 exceeds 30 degrees, the above-described reinforcing effect is reduced, and the ground surface of the block 5 cannot be lifted, and the impact force when the block edge strikes the road surface cannot be dispersed. The disturbance effect of the air vibration by the rib is reduced. For this reason, the angle θ1 is more preferably 25 degrees or less, and further preferably 20 degrees or less.

  Since the radial rib 8 of the present embodiment is formed on the entire surface of the axial wall surface 6, the above-described noise performance and steering stability performance are efficiently improved.

  Further, a plurality of circumferential ribs 9 extending in the length direction of the main groove 3 are provided on the circumferential wall surface 7 in the groove depth direction. Such circumferential ribs 9 increase the rigidity of the block 5 in the tire circumferential direction, so that it can resist bending deformation due to traction, etc., suppress the lifting of the block 5, and reduce the rigidity of the block 5 in the tire radial direction. In addition to improving ride comfort, the ground contact area can be secured following the bending deformation. Therefore, the steering stability performance of the tire according to the present embodiment is improved.

  Further, the circumferential rib 9 needs to be formed at an angle γ1 of 10 degrees or less with respect to the tread surface 2A (or a plane parallel thereto). That is, if the angle γ1 exceeds 10 degrees, the rigidity of the block 5 in the tire circumferential direction is reduced, and the block 5 cannot be prevented from being lifted. For this reason, the angle γ1 is more preferably 7 degrees or less, and further preferably 4 degrees or less. In the present embodiment, the angle γ1 is 0 degree.

  As described above, the tire of the present invention has a plurality of ribs 8 each having an arrangement angle defined within a certain range on the axial wall surface 6 and the circumferential wall surface 7 of the block 5 divided by the main groove 3 and the lateral groove 4. , 9 is provided, the rigidity in the tire circumferential direction of the block 5 is increased, and the rigidity in the tire radial direction is decreased to follow the bending deformation to ensure a ground contact area. In addition, noise is reduced by disturbing air vibrations using ribs. Thereby, the fall of steering stability performance is suppressed and noise performance improves.

  Further, as in the present embodiment, the circumferential rib 9 is located on the tread side region T on the outer side in the tire radial direction from the position spaced 10% of the groove depth D1 of the main groove 3 from the groove bottom 3s of the main groove 3. It is desirable to be provided. That is, if the inner end of the tread surface side region T in the tire radial direction is formed at a position less than 10% of the groove depth D1 with respect to the groove bottom 3s, the rigidity of the block 5 in the tire radial direction decreases. The ride performance may deteriorate. On the contrary, if the inner end of the tread surface region T in the tire radial direction is formed at a position that is 70% or more of the groove depth D1 with respect to the groove bottom 3s, the effect of suppressing the lifting of the block 5 is exhibited. There is a risk that it will not be.

  Further, as shown in FIG. 1B, the radial rib 8 and the circumferential rib 9 of the present embodiment are in a cross-sectional view perpendicular to the longitudinal direction of the radial rib 8 and the circumferential rib 9. The sine wave is formed. Such ribs 8 and 9 are useful for ensuring the rigidity of the wall surfaces 6 and 7 in order to suppress stress concentration acting on the axial wall surface 6 and the circumferential wall surface 7. 3A to 3C show another embodiment of the radial rib 8. As described above, the radial rib 8 may be formed in, for example, a mountain shape, a triangular shape, or a quadrangular shape from the viewpoint of manufacturing cost or the like. From the same point of view, the circumferential rib 9 can also have a shape as shown in FIGS. 3 (a) to 3 (c).

  Further, as shown in FIG. 1B, the ribs 8 and 9 are distances in the tire circumferential direction or the axial direction between the concave inner end 5i and the convex outer end 5e of the ribs 8 and 9. If the protrusion width H is less than 0.5 mm, the effect of improving the rigidity of the block 5 may not be exhibited. Conversely, if the protrusion width H exceeds 4.0 mm, the drainage may not flow smoothly. is there. Accordingly, the protrusion width H is preferably 1.0 mm or more, more preferably 1.5 mm or more, and preferably 3.5 mm or less, more preferably 3.0 mm or less. From the same viewpoint, the number of the ribs 8 and 9 is preferably 3 or more, more preferably 4 or more, and preferably 13 or less, more preferably 11 or less.

  FIG. 4 (a) describes another embodiment of the present invention. In this aspect, the radial ribs 8 include outer radial ribs 8a provided on both sides 5s of the block 5 in the tire axial direction, and intermediate radial ribs provided between the outer radial ribs 8a. 8b. The protrusion width H2 of the intermediate radial rib 8b is formed larger than the protrusion width H1 of the outer radial rib 8a. In such a radial rib 8, the outer radial rib 8 a ensures the rigidity in the tire circumferential direction, and the intermediate radial rib 8 b effectively disturbs the vibration of the air in the lateral groove 4. Therefore, the radial rib 8 of the embodiment is useful for improving noise performance while ensuring steering stability performance.

  In addition, the intermediate radial rib 8b is useful for improving noise performance, but when the protrusion width H2 becomes excessively large, the rigidity in the tire circumferential direction of the block 5 is reduced. From this point of view, the protrusion width H2 is preferably 120% or more, more preferably 150% or more, and preferably 250% or less, more preferably 200% or less of the protrusion width H1 of the outer radial rib 8a. Is desirable.

  FIG. 4B shows still another embodiment of the present invention. In this aspect, the protruding width H of the circumferential rib 9 gradually increases from the groove bottom 3s toward the tread surface 2A. Such circumferential ribs 9 are useful for increasing the rigidity on the tread tread surface 2A side where a large bending stress due to traction or the like acts.

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

Pneumatic tires (size: 195 / 65R15) having the pattern of FIG. 1 and based on the specifications in Table 1 were manufactured and tested for their respective performance. The common specifications are as follows.
Grounding width TW: 148mm
<Center main groove>
Groove width W1 / Grounding width TW: 4.0%
Groove depth D1: 8.7 mm
<Center lateral groove>
Groove width W2a: 5.0 mm
Groove depth: 8.7mm
<Shoulder lateral groove>
Groove width W2b: 5.0 mm
Groove depth: 6.0 mm

<Steering stability>
Each sample tire is mounted on all wheels of a rear-wheel drive vehicle with a displacement of 2000cc with a rim (15x7J) and internal pressure (200kPa), and runs on a test course on an asphalt road surface with one driver on the steering wheel. In addition, characteristics relating to rigidity, traction, etc. were evaluated by sensory evaluation of the driver. The results are displayed as a score with a maximum score of 10. The larger the value, the better.

<Ride comfort performance>
The ride comfort after running on the test course was indicated by a rating with a maximum score of 10 in the driver's sensory evaluation. A higher number is better

<Noise performance>
Based on the actual vehicle coasting test stipulated in JASO / C / 606, the above test vehicle coasts on a straight test course (asphalt road surface) for a distance of 50 m at a passing speed of 60 km / h, At the point, the maximum level of passing noise dB (A) was measured with a stationary microphone installed at a position 7.5 m laterally from the running center line and 1.2 m from the road surface. The results are shown as an index with the best noise level as 10. The larger the value, the better.
The test results are shown in Table 1.

2 tread portion 3 main groove 4 transverse groove 5 block 6 axial wall surface 7 circumferential wall surface 8 radial rib 9 circumferential radial rib

Claims (5)

The tread portion is provided with a main groove extending continuously in the tire circumferential direction and a plurality of horizontal grooves extending in a direction intersecting with the main groove, whereby the block divided by the main groove and the horizontal groove is a tire. A pneumatic tire in which block rows arranged in the circumferential direction are formed,
The transverse groove has an angle with respect to the tire circumferential direction of 80 degrees or more,
The block has an axial wall surface facing the lateral groove, and a circumferential wall surface facing the main groove,
On the axial wall surface, a plurality of radial ribs extending in the groove depth direction at an angle of 30 degrees or less with respect to the normal direction of the block tread surface are provided apart in the length direction of the lateral groove,
A plurality of circumferential ribs extending in the longitudinal direction of the main groove at an angle of 10 degrees or less with respect to the block tread surface are provided in the circumferential wall surface in the groove depth direction .
The radial ribs include outer radial ribs provided on both sides in the tire axial direction of the block, and intermediate radial ribs provided between the outer radial ribs,
The pneumatic tire according to claim 1, wherein a protruding width of the intermediate radial rib is larger than a protruding width of the outer radial rib . The pneumatic tire according to claim 1 , wherein a protruding width of the intermediate radial rib is 150% to 200% of a protruding width of the outer radial rib .   3. The pneumatic tire according to claim 1, wherein the circumferential rib is provided in a tread side region on the outer side in the tire radial direction from a position separated from a groove bottom of the main groove by 10% of a groove depth of the main groove. The pneumatic tire according to any one of claims 1 to 3, wherein a protrusion width of the circumferential rib gradually increases from a groove bottom of the main groove toward a tread surface. The pneumatic tire according to any one of claims 1 to 4, wherein both ends in the tire circumferential direction of the circumferential rib terminate without contacting both ends in the tire circumferential direction of the circumferential wall surface.

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