JP4586537B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can reduce air column resonance generated in a circumferential groove while maintaining wet performance.

  There is a problem related to air column resonance as a factor of tire noise outside the vehicle. The air column resonance is a resonance generated in a space (air column) surrounded by the road surface and the circumferential groove when the tire rolls, and causes pattern noise and the like.

  In this problem, the technique described in Patent Document 1 is known for conventional pneumatic tires. In a conventional pneumatic tire, a plurality of circumferential grooves that are continuous in the tire circumferential direction are formed in the tread portion. And the convex part from which height differs in the groove bottom of the circumferential groove | channel is provided in the pattern which repeats an unevenness | corrugation along a tire circumferential direction. In a conventional pneumatic tire, this configuration suppresses the generation of air column resonance sound during tire rolling.

  Here, the conventional pneumatic tire has a configuration in which the generation of air column resonance is suppressed by changing the height of the arranged convex portions. However, in such a configuration, when traveling on a wet road, the convex portion serves as a weir at a portion where a tall convex portion (having a large convex amount) is installed, and blocks the flow of water in the circumferential groove. Then, the drainage function of the circumferential groove was hindered, and there was a problem that the wet performance of the tire was lowered.

JP 2002-211210 A

  Therefore, the present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire capable of reducing air column resonance generated in a circumferential groove while maintaining wet performance.

In order to achieve the above object, a pneumatic tire according to the present invention has at least one circumferential groove in a tread portion, a convex portion is formed on a groove bottom of the circumferential groove, and the convex The portion extends in the circumferential direction of the tire in the circumferential groove and has a wavy shape having an amplitude in the width direction of the tire, so that generation of air column resonance from the circumferential groove is reduced. The wave-like wavelength varies with respect to the tire circumferential direction, and the wave-like wavelength has a length dimension in the range of 0.5 times or more and 10 times or less of the tire ground contact length. And

In this pneumatic tire, the convex portion has a wave shape, and the generation of air column resonance from the circumferential groove is reduced by adjusting the wavelength of the wave shape. In such a configuration, it is difficult for the water flow to be blocked in the circumferential groove by the convex portion as compared with the conventional pneumatic tire. Thereby, there exists an advantage by which the fall of the wet performance of a tire is suppressed.
Moreover, in this pneumatic tire, since the wavelength of the convex portion is configured to change with respect to the tire circumferential direction (frequency modulation), amplification of sound generated by the convex portion is suppressed. Thereby, there exists an advantage by which a noise outside a vehicle is reduced.
Further, in this pneumatic tire, since the wavelength of the convex portion is in the range of 0.5 times or more and 10 times or less of the tire contact length, the air column resonance noise is effectively suppressed and the wet performance of the tire There is an advantage that is maintained. The tire contact length is the tread surface and the road surface when the pneumatic tire is filled with air at an air pressure corresponding to the maximum load capacity specified by JATMA and a load corresponding to 75% of the maximum load load is applied. And the length of the contact surface in the tire circumferential direction.

  In the pneumatic tire according to the present invention, the convex portion has a length that is a non-integer multiple of the wavy wavelength of the convex portion relative to the tire ground contact length l.

  In this pneumatic tire, since the wavelength of the convex portion has a length dimension that is a non-integer multiple of the tire contact length l, there is an advantage that the amplification of the air column resonance sound is more effectively suppressed.

  Further, in the pneumatic tire according to the present invention, the plurality of convex portions are formed with respect to one circumferential groove, and these convex portions are arranged with a wave-like phase shifted from the tire circumferential direction. ing.

  In this pneumatic tire, a plurality of convex portions are formed with respect to one circumferential groove, and these convex portions are arranged with a wave-shaped phase shifted from the tire circumferential direction. Compared with a configuration in which only a single convex portion is formed in the circumferential groove, there is an advantage that air column resonance is more effectively suppressed.

  Further, the pneumatic tire according to the present invention has a plurality of the circumferential grooves in the tread portion, the convex portions are formed on the groove bottoms of the circumferential grooves, and the different circumferential grooves. Between convex parts, it is comprised so that the wavelength of the wavy shape may mutually differ.

  In this pneumatic tire, the wave-like wavelengths of the convex portions of the different circumferential grooves are different from each other, and therefore the frequency of sound generated by each convex portion is different from each other. Thereby, amplification of such sound is suppressed, and there is an advantage that noise outside the vehicle is reduced.

  According to the present invention, the convex portion has a wavy shape, and the occurrence of air column resonance from the circumferential groove is reduced by adjusting the wavelength of the wavy shape. There is an advantage that the decrease of the is suppressed.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements of the embodiments described below include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  1 is a plan view showing a tread portion of a pneumatic tire according to Embodiment 1 of the present invention. 2 and 3 are a development view in the tire circumferential direction (FIG. 2) and a cross-sectional view in the tire meridian direction (FIG. 3) showing the convex portions formed in the tread portion. 4 and 5 are explanatory views showing a modification of the convex portion shown in FIG. FIG. 6 is a graph showing the relationship between the frequency of the convex portion and the pattern noise. FIG. 7 is a graph showing the relationship between the frequency of the convex portion and the wet performance. 8 and 9 are explanatory views showing a modification of the convex portion described in FIG.

  In this pneumatic tire 1, a circumferential groove 2 is formed in the tread portion (see FIG. 1). The circumferential groove 2 extends linearly with respect to the tire circumferential direction, and at least one (here, two) is formed. The circumferential groove 2 has a convex portion 21 formed on the bottom of the groove (see FIGS. 2 and 3. In FIG. 2, the convex portion 21 is indicated by a wavy curve). The convex portion 21 has a rail shape with a substantially trapezoidal cross section, and at least one is formed for all the circumferential grooves 2.

  Moreover, the convex part 21 is comprised so that it may have a wavy shape in planar view of a tread part. Here, the wave shape includes, for example, a smooth sine wave shape and a zigzag saw wave shape. The convex portion 21 extends in the tire circumferential direction, has a constant amplitude A in the tire width direction (the groove width direction of the circumferential groove 2), and is continuously formed over the entire tire circumference. Yes. Further, the convex portion 21 is configured such that the dimension in the tire width direction (twice the amplitude A) is substantially the same as the groove width of the circumferential groove 2. That is, the convex portion 21 is configured such that both widths (upper and lower ends of the amplitude A) are in contact with the side wall of the circumferential groove 2.

  Moreover, the convex part 21 is formed so that it may protrude from a groove bottom face by sectional view of a tire meridian direction. The convex portion 21 has a constant height (convex amount) h over the entire circumference of the circumferential groove 2, and the height h is substantially half of the groove depth of the circumferential groove 2. It is configured.

[Function and effect]
When the tire rolls, a space surrounded by the circumferential groove 2 and the ground contact surface becomes an air column, and a resonance sound (air column resonance sound) is generated in the air column. On the other hand, in this pneumatic tire 1, since the convex part 21 is formed in the groove bottom of the circumferential groove | channel 2, generation | occurrence | production of the resonance sound in an air column is suppressed by this convex part 21. FIG. As a result, the noise outside the vehicle is reduced and the uniformity of the tire is improved.

  Here, in the conventional pneumatic tire, a convex group is formed at the groove bottom of the circumferential groove, and the convex amount (height in the groove depth direction) of the convex group is adjusted, thereby causing air column resonance. The generation of sound was suppressed (see Patent Document 1). On the other hand, in this pneumatic tire 1, the convex portion 21 has a wavy shape, and the generation of air column resonance from the circumferential groove 2 is reduced by adjusting the wavelength λ of the wavy shape. . That is, instead of the convex amount of the convex portion 21 (the convex amount is constant in this embodiment), the occurrence of air column resonance is suppressed by the change (amplitude A) in the groove width direction of the convex portion 21 in the circumferential groove 2. The Therefore, in this pneumatic tire 1, it is difficult for the water flow in the circumferential groove 2 to be blocked by the convex portion 21 as compared with the conventional pneumatic tire. Thereby, there exists an advantage by which the fall of the wet performance of a tire is suppressed.

[Modification]
Further, in this pneumatic tire 1, convex portions 21 are formed in all circumferential grooves 2 (see FIG. 1). This is because the generated air column resonance noise is reduced in all circumferential grooves 2. This is preferable. However, the present invention is not limited to this, and the convex portion 21 only needs to be formed in at least one circumferential groove 2 (not shown). Moreover, it is more preferable that the convex portion 21 is formed in the main circumferential groove 2 where the generation of air column resonance sound is remarkable.

  Further, in the pneumatic tire 1, the convex portion 21 has a substantially sinusoidal shape in plan view of the tread portion (see FIGS. 1 and 2). (See FIG. 4). Moreover, the wavy shape of the convex part 21 can be arbitrarily selected within the range obvious to those skilled in the art.

  Moreover, in this pneumatic tire 1, although the convex part 21 is formed in linear (substantially rail shape) in planar view of the tread part (refer FIG. 3), this is because groove | channel cross-sectional area reduces. This is preferable in that the air column resonance is reduced. However, the present invention is not limited to this, and the convex portion 21 may be configured by a group of blocks that are arranged in the tire circumferential direction and arranged (pitch arrangement) (see FIGS. 4 and 5), or a chain shape or a mesh shape. (May be omitted).

  In the pneumatic tire 1, the convex portion 21 is configured such that the width (twice the amplitude A) is substantially the same as the groove width of the circumferential groove 2. In such a configuration, since the convex portion 21 is formed over the entire groove width, there is an advantage that the generation of air column resonance is more effectively reduced. However, the present invention is not limited to this, and the convex portion 21 may be configured such that the amplitude thereof is smaller than the groove width of the circumferential groove 2 (not shown).

  Further, in the pneumatic tire 1, the convex portion 21 is configured to have a substantially trapezoidal shape or a substantially rectangular shape in a cross-sectional view in the tire meridian direction. It is preferable in that it can be easily pulled out. However, the present invention is not limited to this, and the convex portion 21 may have an arbitrary cross-sectional shape.

  Further, the pneumatic tire 1 is configured such that the height of the convex portion 21 is substantially half the groove depth of the circumferential groove 2 in a sectional view in the tire circumferential direction. Such a configuration is preferable in that the function of the circumferential groove 2 is ensured as compared with the case where the height of the convex portion 21 is configured to have the same dimension as the groove depth of the circumferential groove 2. Specifically, since the convex portion 21 does not block the circumferential groove 2, the drainage function of the circumferential groove 2 is ensured. Thereby, there exists an advantage by which the wet performance of a tire is maintained.

[Wavelength (period)]
According to the inventors' research, if the wavelength (period) λ of the convex portion 21 is too short, the effect of suppressing the air column resonance noise is lowered, and conversely, if the wavelength λ is too long, the wet performance of the tire is lowered. (See FIGS. 6 and 7). Here, the wavelength λ of the convex portion 21 refers to a length dimension in the tire circumferential direction per one cycle (unit vibration) of the wavy shape in a plan view of the tread portion.

  Therefore, in this pneumatic tire 1, the wavelength (period) λ of the convex portion 21 in the tire circumferential direction is in a preferable range from the viewpoint of both the effect of suppressing air column resonance noise and the effect of maintaining wet performance. It is preferable to select arbitrarily according to the tire specifications and the like. Specifically, the wavelength λ of the convex portion 21 is preferably in the range of 0.5 times or more and 10 times or less of the tire contact length l, more than 2 times and 7 times the tire contact length l. More preferably, it is in the following range. Thereby, there is an advantage that air column resonance is effectively suppressed and the wet performance of the tire is maintained.

  Moreover, in this pneumatic tire 1, it is preferable that the wavelength λ of the convex portion 21 has a length dimension that is a non-integer multiple of the tire contact length l. Thereby, there exists an advantage by which amplification of air column resonance sound is suppressed more effectively.

  The tire contact length l is the tread surface in a state where the pneumatic tire 1 is filled with air at an air pressure corresponding to the maximum load capacity specified by JATMA and a load corresponding to 75% of the maximum load load is applied. The length of the contact surface in the tire circumferential direction between the road surface and the road surface (see FIG. 1).

[Frequency modulation]
Further, the pneumatic tire 1 is configured such that the wavelength (period) λ of the convex portion 21 in the tire circumferential direction is constant over the entire circumference of the tire (see FIG. 2). However, the configuration is not limited thereto, and the wavelength λ of the convex portion 21 may be configured to change (frequency modulation) in the tire circumferential direction (see FIG. 7). That is, in this pneumatic tire 1, when the convex portion 21 is viewed in plan over the entire circumference of the tire, the wavelength λ of the convex portion 21 is different in each portion on the tire circumference (in the tire circumferential direction). It is configured to gradually change with time). Here, in the circumferential groove 2, a sound having a specific frequency is generated by the formed convex portion 21. Then, in the said structure, since the frequency of this sound differs in each part on a tire periphery, amplification of this sound is suppressed. Thereby, there exists an advantage by which a noise outside a vehicle is reduced. Even in this configuration, the wavelength λ of the convex portion 21 is preferably in the range of 0.5 times or more and 10 times or less of the tire contact length l, and more than twice the tire contact length l. More preferably, it is in the range of 7 times or less.

[Circumferential groove having a plurality of convex portions]
Moreover, in this pneumatic tire 1, only the single convex part 21 is formed with respect to the one circumferential groove | channel 2 (refer FIG. 1). However, the present invention is not limited thereto, and a plurality of convex portions 21 and 21 may be formed for one circumferential groove 2 (see FIG. 9). Specifically, a plurality of convex portions 21 are formed with respect to one circumferential groove 2 while shifting the waveform phase in the tire circumferential direction. Thereby, compared with the structure in which only the single convex part 21 is formed, there is an advantage that air column resonance is more effectively suppressed.

[Relationship between protrusions of different circumferential grooves]
In the pneumatic tire 1, a plurality of circumferential grooves 2 and 2 are formed in the tread portion, and convex portions 21 and 21 are formed for the circumferential grooves 2 and 2 (see FIG. 1). ). Here, it is preferable that the wavelengths λ and λ ′ are different between the convex portions 21 and 21 of the different circumferential grooves 2 and 2. In such a configuration, since the frequencies of the sounds generated by the convex portions 21 and 21 are different from each other, amplification of the sounds is suppressed. Thereby, there exists an advantage by which a noise outside a vehicle is reduced.

  Moreover, it is preferable that the convex portions 21 and 21 of the different circumferential grooves 2 and 2 are configured such that the wavelengths λ and λ ′ change in the tire circumferential direction. Thereby, since the amplification of the sound generated by the convex portions 21 and 21 is suppressed in each of the circumferential grooves 2 and 2, there is an advantage that generation of noise outside the vehicle is suppressed. Further, in this configuration, it is preferable that the changes (modulation frequencies) of the wavelengths λ and λ ′ of the convex portions 21 and 21 are different from each other. In such a configuration, it is possible to suppress a situation in which the sound generated by the convex portions 21 and 21 is amplified between the plurality of circumferential grooves 2 and 2. Thereby, there exists an advantage by which generation | occurrence | production of the noise outside a vehicle is suppressed more.

[performance test]
FIG. 10 is a table showing the results of the performance test of the pneumatic tire according to the present invention. In this performance test, a pneumatic tire has a tire size of 195 / 65R15 91H, is assembled to a rim of 15 × 6JJ, and is mounted on a passenger car of an FR car having a displacement of 2000 [cc]. The pneumatic tire is filled with air at an air pressure of 200 [kPa], and a load of 75 [%] of the maximum load load specified by JATMA is applied. And a predetermined test is performed using the pneumatic tire 1 which has the convex part 21, and the conventional pneumatic tire, and index evaluation is performed about the result. The test is performed for pattern noise performance (P / N performance) and wet performance.

  Here, in the pattern noise performance test, in-vehicle sound is measured in a vehicle traveling at a speed of 60 km / h, and the noise level is indexed. In the wet performance test, swivel hydro measurement (lateral load measurement) is performed at a water depth of 7 [mm], and the maximum lateral acceleration during 100R travel is indexed.

First, the pneumatic tire of Conventional Example 1 is a pneumatic tire that does not have the convex portion 21. Index evaluation Ru done the pneumatic tire of the Conventional Example 1 as a reference (100). On the other hand , the pneumatic tire 1 of Invention Example 3 and Reference Examples 1 to 3 is a pneumatic tire having an integral convex portion 21.

As shown in the test results, the pneumatic tire 1 of Invention Example 3 and Reference Examples 1 to 3 are all excellent in pattern noise performance as compared with the pneumatic tire of Conventional Example 1 .

Further, comparing the pneumatic tire 1 of Invention Example 3 and Reference Examples 1 to 3 with the pneumatic tires of Reference Examples 4 and 5 , the wavelength λ is 0.5 to 10 times the tire contact length l. It can be seen that it is preferable to have dimensions. Specifically, it can be seen that when the wavelength λ is smaller than 0.5 times the tire contact length l (0.2 times in Reference Example 4 ), the pattern noise performance is not improved so much. It can also be seen that when the wavelength λ is greater than 10 times the tire contact length l (13 times in Reference Example 5 ), the wet performance is degraded.

Further, when comparing the pneumatic tire 1 of Reference Example 2 and the pneumatic tire 1 of Invention Example 3, in the configuration in which the waveform of the convex portion 21 changes in the tire circumferential direction (frequency modulation), the pattern noise performance is It turns out that it improves more.

  As described above, the pneumatic tire according to the present invention is useful in that it can reduce the air column resonance generated in the circumferential groove while maintaining the wet performance.

It is a top view which shows the tread part of the pneumatic tire concerning Example 1 of this invention. It is a development view of the tire peripheral direction which shows the convex part formed in the tread part. It is sectional drawing of the tire meridian direction which shows the convex part formed in the tread part. It is explanatory drawing which shows the modification of the convex part described in FIG. It is explanatory drawing which shows the modification of the convex part described in FIG. It is a graph which shows the relationship between the frequency of a convex part, and pattern noise. It is a graph which shows the relationship between the frequency of a convex part, and wet performance. It is explanatory drawing which shows the modification of the convex part described in FIG. It is explanatory drawing which shows the modification of the convex part described in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning this invention.

Explanation of symbols

1 Pneumatic tire 2 Circumferential groove 21 Protrusion A Amplitude l Tire contact length λ Wavelength

Claims (4)

The tread portion has at least one circumferential groove, and a convex portion is formed on the groove bottom of the circumferential groove, and
The convex portion has a wavy shape extending in the tire circumferential direction in the circumferential groove and having an amplitude in the tire width direction, and generation of air column resonance from the circumferential groove is reduced. As described above, the wavelength of the wavy shape varies with respect to the tire circumferential direction, and the wavelength of the wavy shape has a length dimension in the range of 0.5 times or more and 10 times or less of the tire ground contact length. Pneumatic tire characterized by. 2. The pneumatic tire according to claim 1 , wherein the convex portion has a length that is a non-integer multiple of the wavy wavelength of the tire with respect to the tire contact length l. The air according to claim 1 or 2 , wherein a plurality of the convex portions are formed with respect to one circumferential groove, and the convex portions are arranged with a wave-like phase shifted from the tire circumferential direction. Tires. The tread portion has a plurality of the circumferential grooves, and the convex portions are respectively formed on the groove bottoms of the circumferential grooves, and
The pneumatic tire according to any one of claims 1 to 3 , wherein the wavy-shaped wavelengths are different between the convex portions of different circumferential grooves.

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