JP5164393B2 - Pneumatic tire - Google Patents

Description

  The present invention includes a tread portion including at least one circumferential groove extending along the tire circumferential direction and at least one row of rib-shaped land portions adjacent to the tread portion, and the circumferential direction in the rib-shaped land portion. A plurality of constricted necks that open to the groove, and an air chamber portion that communicates with the circumferential groove through the constricted neck and has a larger cross-sectional area than the constricted neck, and reduces noise caused by the circumferential groove. In particular, the present invention relates to a pneumatic tire in which the above-described resonator is disposed, and in particular, aims to reduce pitch noise generated by the resonator.

  The noise caused by the circumferential groove extending along the tire circumferential direction is a so-called air column resonance sound, which is in the pipe formed by the circumferential groove and the road surface in the contact area of the tread portion. It is generated by the resonance of air. The frequency of the air column resonance sound is often observed at about 800 to 1200 Hz in a general passenger car, and since the sound pressure level at the peak is high and the frequency band is wide, it occupies a large part of the noise generated by the tire. It will be.

  In addition, since human hearing is particularly sensitive in the above frequency band as shown by the A characteristic, for example, the reduction of the air column resonance is effective in improving the quietness in the feeling surface. It is.

Conventionally, as a method of reducing air column resonance sound, a so-called Helmholtz type resonator composed of a sipe (stenosis neck) opening in a circumferential groove and a resonance chamber (air chamber part) connected to the stenosis neck is used. A technique for absorbing energy in the vicinity of the resonance frequency of air column resonance has been proposed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 5-338411

  However, in the method described in Patent Document 1, the resonator has an effect of reducing the air column resonance caused by the circumferential groove, but has a certain volume of space and periodically exists in the tread portion. Because of this, the resonator itself is pitch noise (which occurs when the tread with some compression rigidity steps on the section of the resonator that does not have compression rigidity, and the edge of the tread strikes the road surface. Noise).

  Therefore, according to the present invention, it is possible to reduce the pitch noise caused by the resonator while maintaining the effect of reducing the air column resonance sound by the resonator by optimizing the arrangement pattern of the resonator. It aims to provide a pneumatic tire.

In order to solve the above problem, the first invention comprises, in the tread portion, at least one circumferential groove extending along the tire circumferential direction, and at least one row of rib-shaped land portions adjacent thereto, In the rib-like land portion, a narrowed neck that opens to the circumferential groove, and an air chamber portion that communicates with the circumferential groove through the narrowed neck and has a larger cross-sectional area than the narrowed neck, and In a pneumatic tire comprising a plurality of resonators for reducing noise caused by directional grooves, at least one narrow groove is connected to the resonator adjacent to the tire circumferential direction in the same rib-shaped land portion. It is characterized in that it is provided so that all of the narrow grooves are present in a section where the shapes projected on are separated from each other. Here, the “circumferential groove” is not only a groove extending linearly along the tire circumferential direction, but also a groove extending in a zigzag shape or a wave shape and making a round in the circumferential direction as a whole tire. Further, the “cross-sectional area” of the resonator means a cross-sectional area in each plane orthogonal to the virtual center line of each of the stenosis neck and the air chamber portion, and “section” means along the tire circumferential direction. It means a section. Further, the “thin groove” includes not only a groove that keeps an open state on the tread portion tread surface even at the time of ground contact but also a so-called sipe that is completely closed at the time of ground contact.

In the above pneumatic tire according to the configuration, the pre-Symbol resonator, it is preferable to periodically present in the tread portion.

Further, the second invention is provided with at least one circumferential groove extending along the tire circumferential direction in the tread portion and at least one row of rib-shaped land portions adjacent to the tread portion, And a narrowed neck that opens into the circumferential groove, and an air chamber that communicates with the circumferential groove through the narrowed neck and has a larger cross-sectional area than the narrowed neck, and is caused by the circumferential groove In a pneumatic tire in which a plurality of resonators that reduce noise are arranged, a shape in which at least one narrow groove is projected on the tire equatorial plane with the resonator adjacent in the tire circumferential direction within the same rib-shaped land portion. It is characterized in that it is provided so that all of the narrow grooves exist outside the overlapping sections.

In the above pneumatic tire according to the configuration, the pre-Symbol resonator, it is preferable to periodically present in the tread portion.

  In the pneumatic tires according to the first and second inventions, a section having relatively large compression rigidity in the rib-shaped land portion, that is, in the case of the first invention, adjacent to the tire circumferential direction in the same rib-shaped land portion. In the section where the shape projected on the tire equatorial plane is spaced apart from each other, and in the case of the second invention, the resonator adjacent to the tire circumferential direction within the same rib-shaped land is placed on the tire equatorial plane. By disposing at least one narrow groove that reduces the compression rigidity of the rib-like land portion in a section where the projected shapes do not overlap with each other, the compression rigidity of the section decreases. The compression rigidity on the circumference of the rib-like land portion is made uniform.

  Pitch noise is generated when the tread with some compression rigidity is stepped on the road surface of the resonator, which has no compression rigidity, and the edge of the tread hits the road surface. If the compression rigidity on the circumference of the rib-like land portion is made uniform, the impact input can be reduced and the pitch noise can be reduced.

  Embodiments of the first invention will be described below with reference to the drawings. FIG. 1 is a view showing a tread pattern of a pneumatic tire according to an embodiment of the present invention, particularly a pneumatic tire for passenger cars (hereinafter referred to as “tire”), and FIG. 2 is a tread shown in FIG. It is a projection view which shows a shape when the principal part of the tire which has a pattern is projected on a tire equator surface.

  As shown in FIG. 1, the tire according to this embodiment includes at least one circumferential groove 1 extending in the tire circumferential direction in the tread portion, at least one row of rib-like land portions 2 adjacent thereto, Resonators 3 arranged in the tire circumferential direction within the same rib-like land portion 2 that reduce noise generated by resonance in the pipe formed by the directional groove 1 and the road surface, and further adjacent to the tire circumferential direction A narrow groove 4 is provided between the resonators 3.

  As shown in FIG. 2, the resonator 3 is disposed so that projected shapes 3 </ b> P obtained by projecting the resonator 3 adjacent in the tire circumferential direction on the tire equatorial plane in the same rib-shaped land portion 2 are separated from each other. . 2 indicates a section along the tire circumferential direction in which the projection shapes 3P are separated from each other, and a section B indicates a section along the tire circumferential direction in which the projection shape 3P exists. It is.

The narrow grooves 4 are arranged such that a projection shape 4P obtained by projecting the narrow grooves 4 on the tire equatorial plane is entirely within the range of the section A as indicated by a broken line in FIG. In addition, since the narrow groove 4 is for reducing the compression rigidity of the section A having a relatively high compression rigidity, the planar shape thereof may be any shape. For example, it may be a linear groove as shown in FIG. 1, or may be a curved shape, a zigzag shape, or a combination thereof. Further, the number may be one or more. However, in order not to reduce the compression rigidity more than necessary, it is preferable to set the depth and width of the narrow groove 4 within a depth of 7 mm, a width within 5 mm, or the cross-sectional area of the narrow groove 4 within 35 mm ² , for example. .

  As shown in FIG. 1, the resonator 3 opens at one end of the circumferential groove 1 and ends at the other end within the rib-shaped land portion 2, and at the other end side of the rib-shaped land portion 2. An air chamber portion 3a having a required volume that opens to the surface, and a constriction neck 3b that allows the air chamber portion 3a and the circumferential groove 1 to communicate with each other and can be embedded in the rib-like land portion 2; Consists of. Further, the cross-sectional area in the plane orthogonal to the virtual center line CL1 of the air chamber 3a is larger than the cross-sectional area in the plane orthogonal to the virtual center line CL2 of the narrowed neck 3b.

として表すことができるので、この共鳴周波数ｆは、周方向溝２の気柱共鳴周波数との関連の下で、狭窄ネック３ｂの長さにｌ_ｈ、狭窄ネック３ｂの断面積をＳ（半径ｒ）及び気室部３ａの容積Ｖの大きさを選択的に変えることによって、所要に応じて変化させることができる。 The resonator 3 that can be configured in this manner has a Helmholtz type as schematically shown in FIG. 3A when the rib opening of the air chamber portion 3a and the narrowed neck 3b are both sealed by the road surface. The resonance frequency f of the resonator 3 is such that the length of the constriction neck 3b is l _h , the radius of the constriction neck is r, the cross-sectional area of the constriction neck 3b is S, and the air chamber When the volume of the portion 3a is V and the sound speed is c,

Since it can be expressed as, the resonance frequency f, under the context of the circumferential groove 2 of the columnar resonance frequency, the length of the narrowed neck 3b l _h, the cross-sectional area of the narrowed neck 3b S (the radius r ) And the volume V of the air chamber 3a can be selectively changed as required.

  In addition, when the cross-sectional shape of the constriction neck 3b of the resonance part 3 is not circular, the radius r in the above equation can be obtained by calculating backward based on the cross-sectional area of the constriction neck 3b. The coefficient “1.3” in the equation has a different value depending on the literature, but it can be generally obtained from an empirical equation and is used as one coefficient in the present invention.

  The air chamber portion 3a of the resonator 3 may be one having the same cross-sectional area as the opening area over the entire depth direction, but the cross-sectional area gradually increases in the depth direction. Or you may apply what decreases gradually. Further, the bottom wall of the air chamber 3a may be a substantially flat surface, or may be a convex or concave curved surface toward the opening side.

  Furthermore, in this embodiment, the opening shape of the air chamber portion 3a of the resonator 3 to the surface of the rib-like land portion 2 is rectangular, but this opening shape is not limited to this, and is polygonal, circular, Ellipsoidal shapes, other closed curve shapes, irregular closed shapes, etc. can be applied.

  Alternatively, instead of the Helmholtz resonator as described above, the air chamber 3a and the narrowed neck 3b are regarded as the first duct 3a ′ and the second duct 3b ′, respectively, as shown in FIG. A stepped tube type resonator comprising connecting pipes interconnecting them can also be applied. In this case, the resonance frequency f can be obtained as described below.

For the stepped tube resonator, the acoustic impedance on the first pipeline 3a ′ side at the boundary is Z ₁₂ , the acoustic impedance on the second pipeline 3b ′ side in the boundary is Z ₂₁ , and the cross-sectional area of the first pipeline 3a ′. Is S ₁ , and the cross-sectional area of the second pipeline 3b ′ is S ₂ ,
Z ₂₁ = (S ₂ / S ₁ ) · Z ₁₂
The relationship is established.

'For the boundary condition, x = 0 at _V 2 _{= V} ⁰ e jwt, when at x = _{l 2} and _{P 2 / V 2 = Z 21} , second conduit 3b' second conduit 3b from the opening of distance the sound pressure P ₂ which definitive position of x,
_{P 2 = Z c · {(} Z 21 cos (k (l 2 -x)) + jZ c sin (k (l 2 -x))) / (Z c cos (kl 2) + jZ 21 sin (kl 2)) } ・ V ₀ e ^jwt
It is expressed.
Here, l ₂ is the length of the second pipeline 3b ′, V ₂ is the particle velocity distribution of the second pipeline 3b ′, V ₀ is the particle velocity at the input point, j is the imaginary unit, Z _c Is ρc (ρ is the density of air, c is the speed of sound), and k is 2πf / c.

Further, regarding the first pipeline 3a ′, when the boundary conditions are V = ₁ = 0 when x = l ₁ and P ₂ = P ₁ when x = 0, the position of the distance x from the opening of the first pipeline 3a ′ Sound pressure P ₁
P ₁ = Z _c · [Z ₂₁ cos (k (l ₁ −x)) / (cos (kl ₁ ) · {Z _c cos (kl ₂ ) + jZ ₂₁ sin (kl ₂ )})] · e ^jwt
It is expressed.
Here, l ₁ is the length of the first pipe line 3a ′.

Here, since the resonance condition x = 0 and P ₂ = 0,
tan (kl ₁ ) tan (kl ₂ ) − (S ₂ / S ₁ ) = 0, and k, l ₁ , l ₂ , S ₂ , S ₁ , c are determined based on the conditional expression of this resonance. The resonance frequency f can be obtained.

  In the example shown in the figure, the stepped tube type resonator is a combination of pipes that are rectangular parallelepiped. However, to obtain the resonance frequency using the above conditional expression, the cross-sectional area and length of each pipe are determined. Therefore, the shape of the pipe line is not limited to a rectangular parallelepiped, and various shapes can be applied.

  In addition, it is indispensable that one end of the second pipe line 3b ′ is opened by the groove wall of the circumferential groove 1, but the first pipe line 3a ′ and the second pipe line 3b ′ are the grounding surface of the tread surface. Since the closed space is formed by contact with the road surface, the upper end of the closed space can be opened at the surface of the rib, and this point is not limited.

  According to the tire of this embodiment, a section having relatively high compression rigidity in the rib-shaped land portion 2, that is, the resonator 3 adjacent in the tire circumferential direction in the same rib-shaped land portion 2 is projected onto the tire equatorial plane. In the section A in which the projected shapes 3P are separated from each other, the narrow groove 4 for reducing the compression rigidity of the rib-like land portion 2 is disposed, so that the compression rigidity of the section A is lowered. The compression rigidity on the circumference is made uniform. Since the pitch noise is generated when the tread having some compression rigidity steps on the resonator 3 having no compression rigidity and the edge of the tread strikes the road surface. Further, if the compression rigidity on the circumference of the rib-like land portion 2 is made uniform, the input of this hitting can be reduced, and the pitch noise can be reduced. When the narrow groove 4 is not only in the section A in which the projected shapes 3P of the resonator are separated from each other, but also in a section B in which the projected shape 3P exists, the sections A and B If the fluctuation of the compression stiffness in the tire circumferential direction is within 80% of the fluctuation when there is no narrow groove 4, pitch noise can be effectively reduced.

  Further, it is preferable that all of the narrow grooves 4 exist in a section A in which projected shapes 3P obtained by projecting the resonators 3 adjacent in the tire circumferential direction onto the tire equatorial plane are separated from each other. By doing so, it is possible to effectively reduce only the compression rigidity of the section A where the compression rigidity is relatively large, to reduce the pitch noise caused by the resonator 3, and to reduce the rigidity unnecessarily. It does not affect the handling stability.

  Next, an embodiment of the second invention will be described with reference to the drawings. FIG. 4 is a view showing a tread pattern of the tire according to the embodiment of the present invention, and FIG. 5 is a shape when a main part of the tire having the tread pattern shown in FIG. 4 is projected onto the tire equatorial plane. FIG. 4 and 5, the same members as those of the tire of the embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted. Also in the second invention, the resonator may be either a Helmholtz type or a stepped tube type.

  As is clear from the above-described formula 1, the air chamber portion 3a acting on the resonance frequency of the resonator 3 is determined only by its volume V. Therefore, for example, even if the air chamber portion has an elongated shape, or vice versa Needless to say, the same resonance frequency f can be obtained if the volume V is the same (when other components are the same) even if the shape is wide, and therefore the shape of the resonator is tread. It can be freely determined in consideration of pattern design or rib rigidity distribution. Therefore, when the air chamber portion 3a has a long and narrow shape as shown in FIG. 4, the projected shape 3P ′ projected on the tire equatorial plane of the resonator 3 adjacent in the tire circumferential direction in the same rib-shaped land portion 2 is 5 may overlap with each other as indicated by hatching in FIG. In addition, the section C in FIG. 5 shows the section along the tire circumferential direction where these projection shapes 3P ′ overlap each other, and the section D follows the tire circumferential direction where the projection shapes 3P ′ do not overlap each other. It shows the interval.

  In the tire according to this embodiment, the narrow groove 4 has a projection shape 4P ′ obtained by projecting the narrow groove 4 on the tire equatorial plane so that all of the narrow groove 4 exists within the range of the section D as indicated by a dotted line in FIG. Has been placed.

  According to the tire of this embodiment, a section having relatively high compression rigidity in the rib-like land portion 2, that is, the resonator 3 adjacent in the tire circumferential direction in the same rib-like land portion 2 is projected onto the tire equatorial plane. In the section D where the projected shapes 3P ′ are not overlapped with each other, the narrow groove 4 for reducing the compression rigidity of the rib-like land portion 2 is disposed, so that the compression rigidity of the section D is lowered. The compression rigidity on the top is made uniform. Since the pitch noise is generated when the tread having some compression rigidity steps on the resonator 3 having no compression rigidity and the edge of the tread strikes the road surface. Further, if the compression rigidity on the circumference of the rib-like land portion 2 is made uniform, the input of this hitting can be reduced, and the pitch noise can be reduced. When the narrow groove 4 is not only in the section D in which the projection shapes 3P ′ of the resonators do not overlap with each other, but also in the section C in which the projection shapes 3P ′ overlap with each other, the sections C and sections If the fluctuation of the compression stiffness in the tire circumferential direction with D is within 80% of the fluctuation when there is no narrow groove 4, pitch noise can be effectively reduced.

Further, it is preferable that all of the narrow grooves 4 exist within a range of a section D in which the projected shapes 3P ′ obtained by projecting the resonators 3 adjacent in the tire circumferential direction onto the tire equatorial plane do not overlap each other. By doing so, it is possible to effectively reduce only the compression stiffness outside the section C where the compression stiffness is relatively large, and to reduce the pitch noise caused by the resonator 3, and unnecessarily reduce the stiffness. The steering stability is not affected.

  Note that the above description shows only a part of the embodiment of the present invention, and these configurations can be combined with each other or various modifications can be made without departing from the gist of the present invention. .

  Next, in order to confirm the effect of the first invention, the tires of the examples, the tires of the comparative examples, and the tires of the conventional examples are respectively prototyped and subjected to noise tests (evaluation of air column resonance and pitch noise). This will be explained below.

  The tires used in the tests are all radial tires for passenger cars having a tire size of 195 / 65R15, and have the following specifications.

  The tire of Example 1 is a tire according to an embodiment according to the first invention, has the tread pattern shown in FIG. 1, and the dimensions of the four linear circumferential grooves 1 are 6 mm wide and 7 mm deep. The Helmholtz type resonator 3 has an air chamber portion 3a length of 18 mm, width of 6 mm, depth of 7 mm, constriction neck 3b length of 2 mm, width of 1 mm, depth of 2 mm, and an operating frequency of 1061 Hz. The dimensions of the narrow grooves 4 between the resonators 3 are 15 mm in length, 2 mm in width, and 6 mm in depth, and 60 resonators 3 and narrow grooves 4 on the circumference of the rib-like land portion 2 (hereinafter, referred to as “resonator 3”). The case where 60 tires are provided for one circumference of the tire is referred to as 60 pitches on the circumference).

  The tire of Conventional Example 1 has the tread pattern shown in FIG. 6 and is not provided with the narrow groove 4 in the tire of Example 1, and the other specifications are the same as those of the tire of Example 1.

  The tire of Comparative Example 1 has a tread pattern shown in FIG. 7, and has a projection shape 3P in which the resonator 3 is projected on the tire equatorial plane, and is narrow in a section B (see FIG. 2) along the tire circumferential direction. The groove 4 is provided, and other specifications are the same as those of the tire of the first embodiment.

  In the noise test, the tire was mounted on a rim of size 6JJ, an air pressure of 210 kPa (relative pressure) was applied inside, and an indoor drum tester was used to apply these tires to 80 km / h under the action of a load of 4 kN. The lateral sound of the tire at this time was measured according to the conditions specified in JASO C606, and in the air column resonance sound, the overall value of the 1/3 octave band center frequency 800 Hz-1000 Hz-1250 Hz band The relative values for tires (not shown) provided with only four linear circumferential grooves 4 were determined and evaluated. In this case, it is determined that the sound pressure is reduced by 2 dB or more that can be expected to be improved by feeling evaluation of a professional driver by an actual vehicle test. Note that the resonators provided in these prototype tires correspond to the above-described formula (1), and the sound velocity c was 343.7 m / s. On the other hand, for the pitch noise, relative values of the tires of the example and the comparative example with respect to the tires of the conventional example were obtained and evaluated, respectively, at the sound pressure in the primary pitch range. In this case, it was determined that the sound pressure was reduced by 2 dB or more.

  These results are shown in Table 1. As described above, the result of the air column resonance sound is a relative value with respect to the tire provided with only four linear circumferential grooves 4, and the result of the pitch noise is the tire of the example and the comparative example with respect to the conventional example. A negative value (−) indicates that the noise has been reduced, and a positive value (+) indicates that the noise has increased.

  As a result of this test, since the resonator 3 is provided, noise generated in a frequency band of 1000 Hz is reduced by 2.5 dB as compared with a tire provided with only four linear circumferential grooves 1. The reduction effect to the air column resonance by the vessel 3 was confirmed.

  Further, in Comparative Example 1 in which the narrow groove 4 is provided in the section B (see FIG. 2) where the projected shape 3P in which the resonator 3 is projected onto the tire equatorial plane is present, the noise in the pitch primary band is increased by 1.0 dB. In Example 1 in which the narrow groove 4 is provided in the section A (see FIG. 2), it is 3.0 dB smaller, so the effect of reducing the pitch noise by providing the narrow groove 4 according to the first invention is confirmed. It was done.

  Next, in order to confirm the effect of the second invention, the tire of the example, the tire of the comparative example, and the tire of the conventional example were prototyped one by one, and the noise test similar to the previous test was performed, so the following explanation will be given. The description of the conditions and method is omitted. The tires used in the test are all radial tires for passenger cars having a tire size of 195 / 65R15 as in the previous test, and have the following specifications.

  The tire of Example 2 is a tire according to an embodiment according to the second invention, has the tread pattern shown in FIG. 4, and the dimensions of the four linear circumferential grooves 1 are the circumferential grooves 1 of Example 1. The Helmholtz type resonator 3 has an air chamber portion 3a having a length of 36 mm, a width of 3 mm, a depth of 7 mm, and a stenosis neck 3b having a length of 6 mm, a width of 1 mm, and a depth of 2 mm. The frequency is 1061 Hz, and the dimensions of the narrow grooves 4 between the resonators 3 are 15 mm in length, 2 mm in width, and 6 mm in depth, similar to those in the first embodiment. They are arranged alternately at a pitch.

  The tire of Conventional Example 2 has the tread pattern shown in FIG. 8 and is not provided with the narrow groove 4 in the tire of Example 2, and the other specifications are the same as those of the tire of Example 2.

  The tire of Comparative Example 2 has the tread pattern shown in FIG. 9, and the section C along the tire circumferential direction in which the projected shapes 3 </ b> P ′ obtained by projecting the resonator 3 onto the tire equator shown in FIG. 5 overlap each other. The other specifications are the same as those of the tire of the second embodiment.

  These results are shown in Table 2 below.

  As a result of this test, as with the previous test, by providing the resonator 3, the noise generated in the 1000 Hz frequency band is reduced by 2.5 dB compared to the tire in which only four linear circumferential grooves 1 are provided. From this, the reduction effect on the air column resonance sound by the resonator 3 was confirmed.

  Further, in Comparative Example 2 in which the narrow groove 4 is provided in the section C (see FIG. 5) where the projected shapes 3P obtained by projecting the resonator 3 onto the tire equatorial plane overlap each other, the noise in the primary pitch band is 0.7 dB. In the first embodiment in which the narrow groove 4 is provided in the section D (see FIG. 5), it is 2.2 dB smaller. Therefore, the effect of reducing the pitch noise by providing the narrow groove 4 according to the second invention. Was confirmed.

  Thus, according to the pneumatic tire of the present invention, at least one narrow groove for reducing the compression rigidity in the tire circumferential direction of the rib-like land portion is provided at least in the section where the compression rigidity is relatively large in the rib-like land portion. By arranging so that a part exists, the compression rigidity of the said area falls, and the compression rigidity on the periphery of a rib-like land part is equalized. Pitch noise is generated when the tread with some compression rigidity is stepped on the road surface of the resonator, which has no compression rigidity, and the edge of the tread hits the road surface. If the compression rigidity on the circumference of the rib-like land portion is made uniform, the impact input can be reduced and the pitch noise can be reduced.

It is a figure which shows the tread pattern of the pneumatic tire of embodiment of 1st invention. FIG. 2 is a projection view showing a shape when a main part of the tire having the tread pattern shown in FIG. 1 is projected onto the tire equatorial plane. (A) is the figure which showed typically the Helmholtz type resonator and (b) each of the stepped tube type resonator. It is a figure which shows the tread pattern of the pneumatic tire of embodiment of 2nd invention. FIG. 5 is a projection view showing a shape when a main part of the tire having the tread pattern shown in FIG. 4 is projected onto the tire equatorial plane. It is a figure which shows the tread pattern of the tire of the prior art example 1. It is a figure which shows the tread pattern of the tire of the comparative example 1. It is a figure which shows the tread pattern of the tire of the prior art example 2. It is a figure which shows the tread pattern of the tire of the comparative example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circumferential groove | channel 2 Rib-like land part 3 Resonator 3a Air chamber part 3b Constriction neck 3a '1st pipe line 3b' 2nd pipe line 3P, 3P 'Projection shape 4P, 4P' Projection shape

Claims (3)

The tread portion includes at least one circumferential groove extending along the tire circumferential direction and at least one row of rib-shaped land portions adjacent to the tread portion, and the rib-shaped land portion opens into the circumferential groove. A plurality of resonators configured by a constriction neck and an air chamber portion communicating with the circumferential groove through the constriction neck and having a cross-sectional area larger than that of the constriction neck, and reducing noise caused by the circumferential groove; In the pneumatic tire formed,
At least one narrow groove is provided in the same rib-shaped land so that all of them exist in a section formed by projecting the resonators adjacent to the tire circumferential direction on the tire equator plane. A pneumatic tire characterized by that. The tread portion includes at least one circumferential groove extending along the tire circumferential direction and at least one row of rib-shaped land portions adjacent to the tread portion, and the rib-shaped land portion opens into the circumferential groove. A plurality of resonators configured by a constriction neck and an air chamber portion communicating with the circumferential groove through the constriction neck and having a cross-sectional area larger than that of the constriction neck, and reducing noise caused by the circumferential groove; In the pneumatic tire formed,
At least one narrow groove is provided so that all of them exist outside the section where the resonators adjacent to each other in the tire circumferential direction in the same rib-shaped land portion are projected on the tire equatorial plane. A pneumatic tire characterized by that. The pneumatic tire according to claim 1, wherein the resonator is periodically present in a tread portion.

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