JP6514516B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having excellent noise performance.

  In general, there is air column resonance as noise generated by the tire. The air column resonance noise is generated when air passing through a pipe formed by a main groove extending in the tire circumferential direction and a road surface resonates at a specific frequency.

  For example, Patent Document 1 below proposes a pneumatic tire in which air column resonance noise is reduced. Specifically, the tire of Patent Document 1 is provided with a narrow rib along the main groove to suppress air resonance.

  However, even with the pneumatic tire of Patent Document 1, there is room for further improvement in the improvement of noise performance.

Japanese Patent Application Laid-Open No. 10-086611

  SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and has as its main object to provide a pneumatic tire having excellent noise performance.

  The present invention is a pneumatic tire provided with a tread portion, wherein the tread portion is provided with a main groove continuously extending in the circumferential direction of the tire and at least one side of the main groove adjacent to the main groove and the main groove A narrow groove continuously extending in the tire circumferential direction with a groove width smaller than the groove and a narrow rib extending between the main groove and the narrow groove are provided, and the axial width of the narrow rib is: It is 0 to 2.0 mm, and the groove depth of the narrow groove is characterized by changing in the tire circumferential direction.

  In the pneumatic tire according to the present invention, the groove width of the narrow groove is preferably 0.5 to 2.0 mm.

  In the pneumatic tire according to the present invention, it is preferable that the narrow groove is provided on both sides of the main groove.

  In the pneumatic tire according to the present invention, the groove depth of the narrow groove is preferably 0.5 to 1.0 times the groove depth of the main groove.

  In the pneumatic tire according to the present invention, it is desirable that the groove depth of the narrow groove repeatedly increases and decreases in the tire circumferential direction.

  In the pneumatic tire according to the present invention, it is preferable that the groove bottom of the narrow groove changes in a sine wave shape, a trapezoidal wave shape, or a rectangular wave shape in the tire circumferential direction.

  In the pneumatic tire according to the present invention, it is desirable that the groove bottoms of the narrow grooves have one pitch length and an amount of amplitude randomly changing in the tire circumferential direction.

  In the pneumatic tire according to the present invention, the main groove includes a shoulder main groove provided closest to the tread ground contact end and a center main groove provided inward of the shoulder main groove in the tire axial direction, and the narrow groove Preferably, the apparatus includes a shoulder groove provided only on one side of the shoulder main groove and a center groove provided on both sides of the center main groove.

  In the pneumatic tire according to the present invention, it is preferable that the middle land portion between the center main groove and the shoulder main groove includes a plain portion continuously extending in the tire circumferential direction on the center main groove side.

  In the pneumatic tire according to the present invention, the tread portion has a main groove continuously extending in the tire circumferential direction and a groove width provided adjacent to at least one side of the main groove and smaller than the main groove in the tire circumferential direction A continuously extending narrow groove and a narrow rib between the main groove and the narrow groove are provided.

  The axial width of the narrow rib is 1.0 to 2.0 mm. Such a narrow rib appropriately vibrates during traveling to suppress air resonance (generation of a stationary wave) in the main groove and reduce air column resonance noise.

  The groove depth of the narrow groove changes in the tire circumferential direction. Thereby, the rigidity of the narrow rib between the main groove and the narrow groove changes in the tire circumferential direction. Since such a narrow rib vibrates irregularly during traveling, resonance of air in the main groove can be suppressed more effectively.

  In addition, such narrow ribs can also be converted into white noise from the impact noise generated by a collision with the road surface, and excellent noise performance is exhibited.

1 is a development view of a tread portion of a pneumatic tire according to an embodiment of the present invention. It is an enlarged view of the center main groove and middle land part of FIG. (A) is the sectional view on the AA line of FIG. 2, (b) is the BB sectional drawing of (a). (A) thru | or (c) is explanatory drawing which shows the shape of the groove bottom of the fine groove in other embodiment. It is an enlarged view of the outer side shoulder land part of FIG. It is an enlarged view of the inside shoulder 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 based on the drawings.
FIG. 1 is a development view of a tread portion 2 of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire 1 of the present embodiment is suitably used, for example, for a passenger car.

  The tread portion 2 of the present embodiment has a tread pattern in which the direction of mounting on a vehicle is designated. The direction of attachment to the vehicle is displayed, for example, by characters or marks on a sidewall portion (not shown) or the like.

  The tread portion 2 is provided with a main groove 3 extending continuously in the tire circumferential direction and a land portion 4 divided into the main groove 3.

  The main groove 3 includes, for example, a shoulder main groove 5 and a center main groove 6.

  The shoulder main groove 5 is provided, for example, closest to the tread ground contact end Te. One shoulder main groove 5 is provided on each tread ground contact end Te side.

  The tread contact end Te is grounded to a flat surface at a camber angle of 0 ° by applying a normal load to a normal tire 1 which is rim-assembled on a normal rim (not shown) and filled with a normal internal pressure and is unloaded. It is the grounding position on the outermost side in the axial direction of the tire when it is made.

  The “regular rim” is a rim that defines the standard 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, In the case of ETRTO, it is "Measuring Rim".

  The “normal internal pressure” is the air pressure specified by each standard in the standard system including the standard on which the tire is based, and in the case of JATMA, the “maximum air pressure”; in the case of TRA, the table “TIRE LOAD LIMITS AT The maximum value described in VARIOUS COLD INFlation PRESSURES, and in the case of ETRTO, it is “INFLATION PRESSURE”.

  "Normal load" is the load defined by each standard in the standard system including the standard on which the tire is based, and if it is JATMA, "maximum load capacity", if it is TRA, the table "TIRE LOAD LIMITS At the time of ETRTO, it is "LOAD CAPACITY".

  Each shoulder main groove 5 is, for example, linear along the tire circumferential direction. Each shoulder main groove 5 may, for example, extend in a wave or zigzag shape in the tire circumferential direction.

  The center main groove 6 is provided, for example, on the inner side in the tire axial direction of the shoulder main groove 5. The center main groove 6 of the present embodiment is, for example, one and is provided on the tire equator C. The center main groove 6 may be provided, for example, one on each side of the tire equator C.

  The center main groove 6 is, for example, linear along the tire circumferential direction. For example, the center main groove 6 may extend in a wave or zigzag shape in the tire circumferential direction.

  The groove width W1 of the shoulder main groove 5 and the groove width W2 of the center main groove 6 are preferably, for example, 3.5 to 6.0% of the tread contact width TW. The tread contact width TW is a distance in the tire axial direction between the tread contact ends Te, Te of the tire 1 in the normal state.

  The groove depth (not shown) of the shoulder main groove 5 and the center main groove 6 is preferably, for example, 5.0 to 15.0 mm in the case of a tire for a passenger car.

  The land portion 4 includes, for example, a shoulder land portion 7 on the axially outer side of the shoulder main groove 5 and a middle land portion 8 between the shoulder main groove 5 and the center main groove 6. The detailed configuration of each land portion 4 will be described later.

  The land portion 4 is provided with a narrow groove 10 adjacent to the main groove 3 and a narrow rib 11 between the main groove 3 and the narrow groove 10.

  As a figure for demonstrating the structure of the narrow groove 10 and the narrow rib 11, the enlarged view of the center main groove 6 and the middle land part 8 is shown by FIG. As shown in FIG. 2, the narrow rib 11 extends, for example, in the tire circumferential direction. For example, the narrow rib 11 may extend continuously in the tire circumferential direction or may be separated by a lateral groove or the like.

  In the present embodiment, the narrow rib 11 provided between the center main groove 6 and the narrow groove 10 is continuous in the tire circumferential direction.

  The axial width W3 of the narrow rib 11 is 1.0 to 2.0 mm. The width W3 is measured, for example, on the tread. Such a narrow rib 11 vibrates more greatly than the land portion 4 (shown in FIG. 1) at the time of traveling while contacting with or separating from the road surface. Such vibration of the narrow rib 11 continuously deforms the width of the main groove (corresponding to the amplitude of air vibration) to suppress the resonance of the air in the main groove, and thus reduce the air column resonance noise. it can. In the case where the width W3 is less than 1.0 mm, the narrow rib 11 may be broken during tire molding. When the width W3 is larger than 2.0 mm, the narrow rib 11 is difficult to vibrate, and there is a possibility that the resonance of the air in the main groove can not be sufficiently suppressed.

  In order to exhibit the above-mentioned effect further, width W 3 in the tire axial direction of the narrow rib 11 is desirably 1.3 to 1.7 mm.

  The narrow groove 10 is provided, for example, adjacent to at least one side of the main groove 3. In other words, the narrow groove 10 may be provided on both sides of the main groove 3.

  The narrow groove 10 extends continuously in the tire circumferential direction. The narrow groove 10 of the present embodiment, for example, extends linearly along the main groove 3. The narrow groove 10 may extend in a wave or zigzag shape in the tire circumferential direction, for example.

  The narrow groove 10 has a groove width W 4 smaller than the main groove 3. The groove width W4 of the narrow groove 10 is, for example, 0.5 to 2.0 mm. The narrow groove 10 of the present embodiment extends in the tire circumferential direction with a constant groove width.

  The AA line sectional view of narrow slot 10 of Drawing 2 and narrow rib 11 is shown in Drawing 3 (a). As shown in FIG. 3 (a), the groove depth d2 of the narrow groove 10 is, for example, preferably 0.5 times or more, more preferably 0.65 times or more of the groove depth d1 of the main groove 3. Preferably, it is 1.00 times or less, more preferably 0.85 times or less. Such narrow grooves 10 help to promote the vibration while maintaining the durability of the narrow rib 11.

  The BB sectional drawing of FIG. 3 (a) is shown by FIG.3 (b). As shown in FIG. 3 (b), the groove depth d2 of the narrow groove 10 changes in the tire circumferential direction (in the lateral direction in FIG. 3 (b)).

  As a result, the rigidity of the narrow rib 11 (shown in FIG. 2 and hereinafter the same) between the main groove 3 and the narrow groove 10 changes in the tire circumferential direction. Since such a narrow rib 11 vibrates irregularly during traveling, resonance of air in the main groove can be suppressed more effectively. In addition, such a narrow rib 11 can also convert the striking noise generated by a collision with the road surface into white noise, and excellent noise performance is exhibited.

  In order to further exert the above-mentioned effect, it is desirable that the groove depth d2 of the narrow groove 10 is repeatedly increased and decreased in the tire circumferential direction.

  The groove bottom 12 of the narrow groove 10 of the present embodiment, for example, changes irregularly in the circumferential direction of the tire. In other words, in the groove bottom 12 of the narrow groove 10, one pitch length L1 and the amplitude amount d3 are randomly changed in the tire circumferential direction. Thereby, the rigidity of the narrow rib 11 changes more irregularly in the tire circumferential direction. Therefore, the resonance of air in the main groove is more effectively suppressed.

  It is desirable that the one pitch length L1 be randomly changed, for example, in the range of 30 to 100 mm, more preferably in the range of 40 to 60 mm. Generally, it is known that air column resonance of a passenger car tire generates a large sound pressure level in the frequency range of 800 to 1200 Hz (wavelength is in the range of 350 to 450 mm). In the present embodiment, when one pitch length is in the above range, the wavelength of vibration of the narrow rib 11 is about 0.1 to 0.2 times the wavelength of the air column resonance sound. Thereby, the resonance of air in the main groove is effectively suppressed by the minute vibration of the narrow rib 11.

  It is desirable that the amplitude amount d3 changes in a range of, for example, 1.0 to 5.0 mm. Thereby, the above-described effect can be obtained while suppressing the pumping noise of the narrow groove 10.

  The groove bottom 12 of the narrow groove 10 is not limited to the shape as described above. In FIGS. 4A to 4C, the shape of the groove bottom 12 of the narrow groove 10 in another embodiment is shown. As shown in FIG. 4A, the groove bottom 12 of the narrow groove 10 may be sinusoidally changed in the tire circumferential direction. The groove bottom 12 of the narrow groove 10 serves to enhance the uniformity of the tire while exhibiting the effects described above.

  As shown in FIG. 4B, the groove bottom 12 of the narrow groove 10 may be changed in a rectangular wave shape in the tire circumferential direction. Since the rigidity of the narrow rib 11 suddenly changes in the tire circumferential direction, the groove bottom 12 of such a narrow groove 10 can further increase the vibration of the narrow rib 11 while enhancing the uniformity of the tire.

  As shown in FIG. 4C, the groove bottom 12 of the narrow groove 10 may be changed in a trapezoidal wave shape in the tire circumferential direction. The groove bottom 12 of such narrow groove 10 smoothes the change in rigidity of the narrow rib 11 in the tire circumferential direction than the rectangular wave-like one shown in FIG. can do.

  The groove bottom 12 of the narrow groove 10 may be one in which one pitch length and amplitude of the waveforms shown in FIGS. 4 (a) to 4 (c) change randomly.

  As shown in FIG. 1, the narrow groove 10 includes, for example, a center narrow groove 13 adjacent to the center main groove 6 and a shoulder narrow groove 14 adjacent to the shoulder main groove 5.

  As a desirable arrangement of the narrow grooves 10, the center narrow grooves 13 are provided, for example, on both sides of the central main groove 6. The shoulder narrow groove 14 is provided, for example, only on one side of the shoulder main groove 5.

  As a result, the noise generated by the center main groove 6 and the shoulder main groove 5 (the sum of air column resonance sound, pumping sound and the like) is turned into white noise, and excellent noise performance is obtained.

  As a further preferable aspect, it is desirable that the shoulder narrow groove 14 be provided only on the tire axial direction outer side of the shoulder main groove 5. Thereby, for example, at the time of turning, the narrow rib 11 is largely deformed to the main groove side, and a higher noise reduction effect can be exhibited. In addition, such a shoulder narrow groove 14 can secure the width of the middle land portion 8 on which a large contact pressure acts, and excellent steering stability is exhibited.

  As a desirable mode, the sum WW 4 of the groove widths of the narrow grooves 10 provided in the tread portion 2 is 5% or less of the tread contact width TW. Such an arrangement of the narrow groove 10 can exert the above-described effects while maintaining steering stability and wear resistance.

  Hereinafter, the detailed configuration of each land portion 4 will be described. The middle land portion 8 includes an outer middle land portion 8A located on the outer side A of the vehicle and an inner middle land portion 8B located on the inner side B of the vehicle. The outer middle land portion 8A and the inner middle land portion 8B have, for example, a point symmetric shape with respect to a point on the tire equator C.

  As shown in FIG. 2, it is desirable that a plurality of middle lug sipes 16 be provided in each middle land portion 8, for example. The middle lug sipes 16 extend, for example, from the shoulder main groove 5 and terminate in the middle land portion 8. Such middle lug sipes 16 suppress distortion of the tread surface of the middle land portion 8 at the time of contact with the ground, and enhance the wear resistance.

  The middle land portion 8 preferably includes, for example, a plane portion 17 continuously extending in the tire circumferential direction on the center main groove 6 side by being provided with the above-described middle lug sipes 16. Such a middle land portion 8 has a large rigidity on the tire equator C side, and serves to exhibit excellent steering stability.

  As shown in FIG. 1, the shoulder land portion 7 includes an outer shoulder land portion 7A provided on the vehicle outer side A and an inner shoulder land portion 7B provided on the vehicle inner side B.

  FIG. 5 shows an enlarged view of the outer shoulder land portion 7A. As shown in FIG. 5, the outer shoulder land portion 7A is provided with an outer shoulder lug groove 20 and an outer shoulder sipe 21.

  For example, the outer shoulder lug groove 20 extends inward in the tire axial direction from the tread ground contact end Te and terminates in the outer shoulder land portion 7A. Such an outer shoulder lug groove 20 exhibits excellent wandering performance while reducing the pumping noise.

  In order to further exert the above-described effects, the axial length L2 of the outer shoulder lug groove 20 is preferably 0.55 or more times the axial width W5 of the outer shoulder land portion 7A, and more preferably 0. It is not less than .60 times, preferably not more than 0.75 times, and more preferably not more than 0.70 times.

  The angle θ1 of the outer shoulder lug groove 20 with respect to the tire axial direction is, for example, 0 to 15 °. As a desirable mode, the angle θ1 gradually increases inward in the tire axial direction. Such an outer shoulder lug groove 20 helps to suppress uneven wear near its inner end.

  The outer shoulder sipes 21 are provided, for example, between the outer shoulder lug grooves 20 adjacent to each other in the tire circumferential direction.

  The outer shoulder sipe 21 is, for example, a closed sipe having an inner end 22 and an outer end 23 located in the outer shoulder land 7A. Such an outer shoulder sipe 21 reduces the impact sound when the outer shoulder land portion 7A is in contact with the ground and helps to improve the noise performance.

  Preferably, the inner end 22 of the outer shoulder sipe 21 is located, for example, axially inward of the inner end 24 of the outer shoulder lug groove 20 in the tire axial direction. Such an outer shoulder sipe 21 can reduce the distortion of the tread surface between the outer shoulder lug groove 20 and the shoulder main groove 5, and can suppress its partial wear.

  FIG. 6 shows an enlarged view of the inner shoulder land portion 7B. As shown in FIG. 6, the inner shoulder land portion 7B is provided with an inner shoulder lug groove 25, an inner shoulder sipe 26, and a connection sipe 27.

  The inner shoulder lug grooves 25 and the inner shoulder sipes 26 have, for example, the same configuration as the outer shoulder lug grooves 20 and the outer shoulder sipes 21 (shown in FIG. 5).

  The connecting sipes 27 extend, for example, from the inner end 28 of the inner shoulder lug groove 25 to the shoulder slot 14. Such a connection sipe 27 can reduce the rigidity of the inner shoulder land portion 7B and enhance the ride comfort.

  The connecting sipe 27 extends, for example, along an imaginary extension line that smoothly extends the inner shoulder lug groove 25. Such connecting sipes 27 serve to suppress uneven wear near the inner end 28 of the inner shoulder lug groove 25.

  The axial length L3 of the connecting sipe 27 is preferably 0.3 times or more, more preferably 0.35 times or more, preferably the axial width W6 of the inner shoulder land portion 7B, and preferably 0.45 It is twice or less, more preferably 0.4 times or less. Such a connection sipe 27 improves the steering stability and the ride comfort in a well-balanced manner.

  As mentioned above, although the especially preferable embodiment of this invention was explained in full detail, this invention can be deform | transformed into a various aspect, and can be implemented, without being limited to embodiment shown.

A pneumatic tire of size 185 / 60R15 having the basic pattern of FIG. 1 was prototyped based on the specifications of Table 1. As Comparative Example 1, as shown in FIG. 7, a narrow groove was not provided, and a pneumatic tire in which other configurations were common was made on a trial basis. The noise performance of each test tire was tested. The common specification and test method of each test tire are as follows.
Mounting rim: 15 × 5.5J
Tire internal pressure: 230kPa

<Noise performance>
The noise was measured when the test tire was run at 60 km / h on a drum tester. The result is an index based on Comparative Example 1 being 100, and the smaller the value, the better the noise performance.
The test results are shown in Table 1.

As a result of the test, it was confirmed that the pneumatic tire of the example exhibited excellent noise performance.

2 tread portion 3 main groove 10 narrow groove 11 small width rib

Claims (8)

A pneumatic tire having a tread portion,
In the tread portion, a main groove continuously extending in the tire circumferential direction, and a thin member provided adjacent to at least one side of the main groove and continuously extending in the tire circumferential direction with a groove width smaller than the main groove a groove, narrow rib is provided et be between the main groove and the narrow grooves,
The main groove includes a shoulder main groove provided closest to the tread ground contact end, and a center main groove provided axially inward of the shoulder main groove in the tire direction.
The axial width of the narrow rib is 1.0 to 2.0 mm,
The groove depth of the narrow groove changes in the tire circumferential direction ,
The narrow groove includes a shoulder narrow groove provided only on one side of the shoulder main groove and a center narrow groove provided on both sides of the center main groove .   The pneumatic tire according to claim 1, wherein a groove width of the narrow groove is 0.5 to 2.0 mm.   The pneumatic tire according to claim 1 or 2, wherein the narrow groove is provided on both sides of the main groove.   The pneumatic tire according to any one of claims 1 to 3, wherein the groove depth of the narrow groove is 0.5 to 1.0 times the groove depth of the main groove.   The pneumatic tire according to any one of claims 1 to 4, wherein the groove depth of the narrow groove repeatedly increases and decreases in the tire circumferential direction.   The pneumatic tire according to claim 5, wherein the groove bottom of the narrow groove changes in a sine wave shape, a trapezoidal wave shape, or a rectangular wave shape in the tire circumferential direction.   The pneumatic tire according to claim 5, wherein the groove bottoms of the narrow grooves randomly change one pitch length and the amount of amplitude in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 7, wherein the middle land portion between the center main groove and the shoulder main groove includes a plain portion continuously extending in the tire circumferential direction on the center main groove side. .

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