JP2019116195A - tire - Google Patents

Abstract

To improve vehicle exterior noise performance by reducing air column resonance sound due to a main groove.SOLUTION: A tire includes muffling means 5 in at least one of the land parts 4 sectioned by a main groove 3. The muffling means 5 includes: a cavity part 10 substantially sealed inside the land part 4 and having both ends in a lengthwise direction which is interrupted inside the land part 4; and a communication hole 13 for communicating between the cavity part 10 and the main groove 3.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tire capable of reducing air column resonance noise generated by a main groove extending in the tire circumferential direction.

  As one of the causes of the external noise, air column resonance noise generated from a main groove extending in the tire circumferential direction is known. The air column resonance noise is generated when the internal air of a pipe surrounded by the main groove and the road surface arranged in the tread portion resonates during traveling. The air column resonance sound has a high peak sound pressure level and includes an offensive frequency range around 1000 Hz, and therefore occupies a large portion of tire noise.

  Therefore, in order to reduce air column resonance noise, Patent Document 1 below includes a sipe on the land portion and a muffling chamber which is a wide portion provided at the bottom of the sipe and one end of which communicates with the main groove. Pneumatic tires have been proposed. In this tire, the muffling chamber constitutes a Helmholtz resonator, and absorbs the energy of air column resonance sound to reduce air column resonance sound.

  However, in the above-mentioned proposal, the muffling chamber is directly conducted to the main groove without passing through the small diameter neck portion. Therefore, the energy absorption effect is insufficient, and further improvement is desired to reduce air column resonance noise (external noise).

JP, 2013-126842, A

  An object of the present invention is to provide a tire which can further reduce air column resonance noise caused by the main groove and improve the external noise performance.

The present invention is a tire comprising, in a tread portion, a main groove extending in the circumferential direction of the tire and a plurality of land portions divided by the main groove,
At least one land section is
A hollow portion which is substantially sealed inside the land portion and in which both longitudinal ends are interrupted inside the land portion;
Small hole communication that connects the cavity with the main groove through the inside of the land and has a cross-sectional area perpendicular to the longitudinal direction smaller than the cross-sectional area perpendicular to the longitudinal direction of the cavity With holes
A first sipe extending from the hollow portion to the tread surface of the land portion;
A muffling means is provided having a second sipe extending from the communication hole to the tread surface of the land portion.

In the tire according to the present invention, the muffling means includes a volume V (mm ³ ) of the hollow portion, a cross-sectional area S (mm ² ) perpendicular to the length direction of the communication hole, and a length of the communication hole It is preferable that L (mm) satisfy the following formula (1).
5.0 × 10 ⁻⁵ ≦ S / (V × L) ≦ 3.0 × 10 ⁻³ --- (1)

  In the tire according to the present invention, it is preferable that one or more of the muffling means be disposed within a contact range where the tread portion contacts the road surface.

  In the tire according to the present invention, the communication hole is connected to the hollow portion at the connection position P, and the distance Lb from one end in the length direction of the hollow portion to the connection position P is the length of the hollow portion It is preferably 0.1 to 0.9 times La.

  In the tire according to the present invention, the first sipe extends zigzag in the length direction in a horizontal cross section parallel to the tread surface, and has a depth in a vertical cross section perpendicular to the length direction line Preferably, it is a three-dimensional sipe extending in a zigzag along the direction.

  In the tire according to the present invention, it is preferable that the three-dimensional sipes have a bending number n of zigzag in the vertical cross section of 2 or more.

  In the tire according to the present invention, the three-dimensional sipe preferably has a sipe depth Hs from the tread surface to the hollow portion of 2 mm or more.

  In the tire according to the present invention, preferably, the three-dimensional sipe has a zigzag amplitude Ws of 1.5 mm or more in the vertical cross section.

In the tire according to the present invention, the plurality of land portions include a first land portion having the muffling means, and a second land portion not having the muffling means, and the first land portion The complex elastic modulus E ^* 1 is preferably larger than the complex elastic modulus E ^* 2 of the second land portion.

In the tire according to the present invention, the difference between the complex elastic modulus E ^* 1 and the complex elastic modulus E ^* 2 is preferably 5.0 MPa or more.

In the tire according to the present invention, the volume V of the hollow portion is preferably in the range of 20 to 4000 mm ³ .

In the tire according to the present invention, the cross-sectional area S of the communication hole is preferably in the range of 1.5 to ²⁰ mm ² .

  In the tire according to the present invention, the length L of the communication hole is preferably in the range of 2 to 50 mm.

  In the present specification, "sipe" means, for example, one having a slit shape having a width of 0.8 mm or less, and closing between wall surfaces at the time of grounding.

  The term "contacting range" means a range of the area of the contact portion where the tread portion comes in contact with the road surface when a normal load is applied to the tire in a reference state in which a normal rim is assembled and filled with a normal internal pressure.

  In the standard system including the standard on which the tire is based, the above-mentioned "regular rim" is a rim defined by the standard for each tire, for example, a standard rim in the case of JATMA, "Design Rim" in the case of TRA, or In the case of ETRTO, it means "Measuring Rim". The above-mentioned "normal internal pressure" is the air pressure specified for each tire, and the maximum air pressure specified in the case of JATMA, and in the case of TRA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFlation PRESSURES", ETRTO If so, it means "INFLATION PRESSURE", but for passenger car tires it is 180 kPa. The above-mentioned "normal load" is the load which the above-mentioned standard sets for every tire, and in the case of JATMA, the maximum load capacity, and in the case of TRA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATIONS If it is ETRTO, it is "LOAD CAPACITY".

  In the present specification, unless otherwise noted, the dimensions and the like of each part of the tire are values specified in the reference state (no load).

  In the present invention, as described above, at least one land portion includes one or more noise reduction means. The muffling means is a hollow portion which is substantially sealed inside the land portion and in which both longitudinal end portions are interrupted inside the land portion, and a communication hole which passes through the inside of the land portion and communicates the main groove and the hollow portion. Have. The hollow portion and the communication hole constitute a Helmholtz resonator, and air column resonance noise due to the main groove can be reduced. Moreover, in the resonator, the hollow portion is electrically connected to the main groove through the communication hole having a small cross-sectional area. Therefore, as compared with the case where the hollow portion is directly opened by the main groove, the energy absorption effect can be enhanced, and the noise reduction effect of air column resonance can be enhanced.

  Further, in the resonator, since the communication hole having a small cross-sectional area is interposed, the hollow portion is less likely to be deformed as compared with the case where the hollow portion is directly opened to the main groove, and the reduction in rigidity of the land portion can be suppressed low.

  Also, the volume of the cavity does not change during the time it takes for the tread to wear and the cavity to be exposed to the surface. Therefore, the muffling performance can be maintained. Moreover, after the middle stage of wear where the hollow portion is exposed, the muffling performance will not be exhibited, but after this middle stage of wear, the groove volume itself of the main groove is reduced and the air column resonance noise is reduced, so the need for muffling Is low, and in particular the problem of external noise does not occur.

  Further, after the middle stage of wear where the hollow portion is exposed, this hollow portion functions as a new tread groove, so that it is possible to suppress the deterioration of the wet performance accompanying the progress of wear.

It is an expanded view of a tread part of a tire of one embodiment of the present invention. It is an enlarged plan view showing a part of land part. It is a perspective view which shows a muffling means notionally. (A) is an A-A cross-sectional view of FIG. 2 showing the noise reduction means, (B) is a cross-sectional view for explaining the number of bends and the width of the zigzag of the three-dimensional sipes. (A), (B) is a conceptual diagram explaining the effect | action of a noise reduction means. It is an expanded view of the tread part which shows the other example of the tire of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. In this example, the case where the tire 1 is a pneumatic tire for a passenger car is shown. However, for example, it may be a pneumatic tire for heavy load vehicles, etc., and can be configured as various tires such as non-pneumatic tires (for example, airless tires) in which the inside of the tire is not filled with pressurized air. .

  As shown in FIG. 1, the tread portion 2 of the tire 1 includes at least one main groove 3 extending continuously in the tire circumferential direction. The tread portion 2 is thereby divided into a plurality of land portions 4.

  In this example, the case where the main groove 3 is constituted by center main grooves 3C and 3C arranged on both sides of the tire equator C and shoulder main grooves 3S and 3S arranged on the tread end Te side is shown. Thereby, the tread portion 2 of this example is the center land portion 4C between the center main groove 3C, 3C, the middle land portion 4M between the center main groove 3C and the shoulder main groove 3S, and the shoulder main groove 3S and the tread end It is divided into a shoulder land portion 4S between Te.

  However, the present invention is not limited to this, for example, a structure in which a middle main groove (not shown) is disposed between the center main groove 3C and the shoulder main groove 3S as the main groove 3, and the center main groove 3C is the tire equator. Various structures may be employed, such as those disposed on C.

  As the main groove 3, a straight groove extending linearly in the circumferential direction of the tire, a zigzag groove extending in a zigzag shape (including a wavy shape), or the like can be appropriately adopted. However, a straight groove is preferable from the viewpoint of obtaining higher advantages of the effects of the present invention. The groove width W3 of the main groove 3 and the groove depth D3 (shown in FIG. 4 (A)) can be variously determined according to the conventional manner.

  At least one land portion of the plurality of land portions 4 includes one or more noise reduction means 5. In the present embodiment, one or more muffling means 5 is disposed in each of the middle land portions 4M and 4M, so that air column resonance noise caused by the center main grooves 3C can be reduced.

  In the present embodiment, the middle land portions 4M and 4M and the center land portion 4C are formed as rib bodies extending continuously in the tire circumferential direction. As described above, in the case of the main groove sandwiched by the rib body (land portion), air column resonance noise is larger than that of the main groove sandwiched by the block row (land portion). Therefore, the advantage of the effect of the present invention can be obtained higher.

  As shown in FIGS. 2 and 3, the muffling means 5 includes a cavity 10 and a communication hole 13.

  The hollow portion 10 is substantially sealed inside the middle land portion 4M, and both ends in the longitudinal direction are interrupted inside the middle land portion 4M. The hollow portion 10 has a tubular shape having a substantially constant cross section, and extends linearly through the inside of the middle land portion 4M. However, the hollow portion 10 may extend in a zigzag in the longitudinal direction.

  The hollow portion 10 of this example extends in the tire circumferential direction. Thereby, the rigid fall of middle land part 4M resulting from hollow part 10 can be suppressed, and hollow part 10 can be formed maintaining dry run performance. The term "stretching in the tire circumferential direction" also includes the case where the tire is inclined at an angle of 5 degrees or less with respect to the tire circumferential direction line. In this example, the case where the plurality of hollow portions 10 are arranged in a line on the tire circumferential direction line, particularly on the width center line (not shown) of the middle land portion 4M is shown.

  The communication hole 13 is in the form of a small hole, and passes through the inside of the middle land portion 4M to electrically connect the hollow portion 10 and the main groove 3 (in this example, the center main groove 3C). The communication hole 13 has a cylindrical shape with a substantially constant cross section, and the cross sectional area S perpendicular to the longitudinal direction is smaller than the cross sectional area S0 perpendicular to the longitudinal direction of the hollow portion 10. In this example, the cross-sectional shape of the communication hole 13 is substantially circular, but a polygonal shape, an elliptical shape, or the like may be employed as appropriate.

  The muffling means 5 further includes a first sipe 8 and a second sipe 9.

  The first sipe 8 extends from the cavity 10 to the tread 4s of the middle land portion 4M. Specifically, the first sipe 8 is provided on the tread 4 s and extends along the cavity 10 and over the cavity 10. Thus, the cavity 10 is formed continuously with the bottom of the first sipe 8.

  When the first sipe 8 is grounded, the wall surface is closed, whereby the cavity 10 is sealed. That is, the cavity portion 10 being "substantially sealed" includes the case where the wall surface is closed and the cavity portion 10 is sealed at the time of grounding. In addition, in the case of the groove which is not closed between the wall surfaces at the time of grounding, it is not included in being "substantially sealed".

  Also, in this example, the case where the first sipe 8 is a three-dimensional sipe 12 is shown. As conceptually shown in FIG. 3, the three-dimensional sipe 12 of the present example includes a zigzag portion extending in the longitudinal direction. In the horizontal cross section parallel to the tread 4s, the zigzag portion extends in a zigzag (including undulations) along the length direction, and in the vertical cross section perpendicular to the length direction, the zig-zag portion extends along the depth direction. In the shape of a letter (including waves). Such a three-dimensional sipe 12 forms a three-dimensional curved surface in which the wall surface of the sipe repeats unevenness in three dimensions. And at the time of grounding, the rigidity can be maintained high by the unevenness of the wall surfaces facing each other being engaged with each other.

  The second sipe 9 extends from the communication hole 13 to the tread 4s of the middle land portion 4M. Specifically, the second sipe 9 is provided on the tread 4s and extends along the communication hole 13 on the communication hole 13. Accordingly, the communication hole 13 is formed continuously with the bottom of the second sipe 9. In this example, the second sipe 9 extends from the main groove 3 (in this example, the center main groove 3C) to the first sipe 8, one end of the second sipe 9 is opened by the center main groove 3C, and the other end is 1 Sipe 8 and T-shaped crossing. In this example, flat straight sipes (one-dimensional sipes) are adopted as the first sipes 8 and the second sipes 9. When the intersection angle α between the second sipe 9 and the first sipe 8 is too small, the strength is reduced at the intersection, and rubber chipping and the like are likely to occur. Therefore, the crossing angle α is preferably 30 degrees or more, and more preferably 40 degrees or more.

  In such a muffling means 5, the wall surface of the first sipe 8 and the wall surface of the second sipe 9 are closed at the time of grounding. Thereby, at the time of grounding, the cavity portion 10 and the communication hole 13 can form the Helmholtz resonator H with one end opening which is opened only by the center main groove 3C.

  As shown in FIGS. 5A and 5B, in the resonator H, the air K1 of the communication hole 13 acts as a mass, and the air K2 of the cavity 10 acts as a spring to constitute a vibration system. Then, when a sound having the same frequency as the natural frequency f of the resonator H is incident, resonance occurs and the energy of the sound is absorbed by the adhesive friction of the air K1.

  Therefore, by setting the natural frequency of the resonator H according to the frequency to be reduced among the air column resonances by the center main groove 3C, the sound of the frequency to be particularly reduced among the air column resonances is reduced Can improve noise performance.

  One or more of such muffling means 5 are disposed within the contact range where the tread portion 2 contacts the road surface. In the present embodiment, one or more muffling means 5 is disposed within the contact range in each middle land portion 4M. As a result, during tire rolling, at each middle land portion 4M, one or more muffling means 5 is constantly present in the contact range, and air resonance noise from each center main groove 3C can be reduced.

Here, the natural frequency f of the resonator H is expressed by the following equation (2). In the equation, c is the speed of sound (m / s), S is the cross-sectional area (mm ² ) perpendicular to the longitudinal direction of the communication hole 13, V is the volume of the cavity 10 (mm ³ ), L is the length of the communication hole 13 (Mm), δ is the open end correction. Therefore, the natural frequency f can be freely adjusted by the cross-sectional area S (mm ² ), the volume V (mm ³ ), and the length L (mm). The opening end correction δ is very small and can be ignored.
f = c / 2π ×× {S / (V × (L + δ))} --- (2)

In the resonator H, it is preferable that the cross-sectional area S (mm ² ), the volume V (mm ³ ), and the length L (mm) satisfy the following equation (1).
5.0 × 10 ⁻⁵ ≦ S / (V × L) ≦ 3.0 × 10 ⁻³ --- (1)

In this case, the natural frequency f of the resonator H can be set in the range of approximately 3.8 × 10 ^{2 to} 2.96 × 10 ³ Hz. In particular, by setting S / (V × L) in the range of 2.2 × 10 ^{−4 to} 4.9 × 10 ⁻⁴ , the natural frequency f can be made to be around 1000 Hz (for example, 800 to 1200 Hz) which is offensive It can be set.

  By providing the cavity 10 at the bottom of the first sipe 8, the first sipe 8 and the cavity 10 can be easily formed by using a tire vulcanizing mold having a conventional structure. That is, in the tire vulcanizing mold, the first sipe 8 and the hollow portion are formed at the time of vulcanization by using a blade in which a columnar body for forming a hollow portion is integrally attached to the tip of the blade body for forming the first sipe. 10 can be formed simultaneously. Similarly, by using a blade in which a columnar body for forming a communication hole is integrally attached to the tip of a blade body for forming a second sipe, a second sipe is formed using a tire vulcanizing mold having a conventional structure. 9 and the communication hole 13 can be formed simultaneously.

  When the first sipe 8 and the second sipe 9 intersect in a T-shape, the rigidity of the middle land portion 4M tends to decrease. However, in this example, a three-dimensional sipe 12 is employed as the first sipe 8. Therefore, at the time of grounding, the irregularities of the wall surfaces mesh in the three-dimensional direction, and the rigidity of the middle land portion 4M can be maintained high. In particular, in the case of a so-called Miura folded structure in which the wall surfaces are combined with parallelograms as the three-dimensional sipe 12, meshing is dense and strong. Therefore, it is preferable at the point which raises the sealing property of the hollow part 10, and improves muffling performance.

  As shown in FIG. 2, the distance Lb from the connection position P at which the communication hole 13 is connected to the cavity 10 to one end in the lengthwise direction of the cavity 10 is 0.1 to 0. 1 of the length La of the cavity 10. It is preferably 9 times. By thus separating the connection position P from the end of the hollow portion 10, it is possible to suppress the decrease in the rigidity of the middle land portion 4M. Further, since the deformation of the hollow portion 10 can be suppressed, it can contribute to the improvement of the muffling effect. From such a viewpoint, the distance Lb is more preferably 0.2 to 0.8 times, and further preferably 0.3 to 0.7 times as long as the length La.

  Further, in the muffling means 5, the volume V of the hollow portion 10 does not change during the period until the tread wears and the hollow portion 10 is exposed to the surface. Therefore, the natural frequency f of the resonator H does not change, and the muffling performance can be maintained. Moreover, after the middle stage of wear where the cavity portion 10 is exposed, the muffling performance is not exhibited. However, after this middle stage of wear, the groove volume itself of the main groove 3 is reduced and the necessity for muffling becomes low. Problem does not occur.

  Further, after the middle stage of wear where the hollow portion 10 is exposed, the hollow portion 10 functions as a new tread groove, so that it is possible to suppress the deterioration of the wet performance accompanying the progress of wear.

  As shown in FIGS. 4A and 4B, in the three-dimensional sipe 12, the number (number of bends) n of the bent portions Q of the zigzag in the vertical cross section is preferably 2 or more, and more preferably 3 or more. Thereby, the rigidity of the middle land portion 4M and the tightness of the hollow portion 10 can be sufficiently maintained by the meshing of the wall surfaces of the sipes. The upper limit of the number of bends n is preferably 5 or less from the viewpoint of mold releasability.

  Further, in order to maintain the rigidity of the middle land portion 4M and maintain the airtightness of the cavity portion 10, the sipe depth Hs from the tread 4s to the cavity portion 10 is preferably 2 mm or more, more preferably 3 mm or more. The upper limit of the sipe depth Hs is preferably in the range of 0.35 to 0.65 times the groove depth D3 of the main groove 3 from the viewpoint of exposing the cavity portion 10 after the middle stage of wear.

  Further, in order to maintain the rigidity of the middle land portion 4M and maintain the airtightness of the hollow portion 10, the amplitude Ws of the zigzag in the vertical cross section of the three-dimensional sipe 12 is preferably 1.5 mm or more, more preferably 2.0 mm or more. The upper limit of the amplitude Ws is preferably 3.0 mm or less from the viewpoint of mold release.

Further, in the present embodiment, the land portion 4 is a first land portion having a muffling means (in the present example, middle land portion 4M) and a second land portion not having the muffling means 5 (a center land portion in the present example). 4C and shoulder land 4S). In the tread rubber, it is preferable to set the complex elastic modulus E ^* 1 of the rubber of the first land portion to be larger than the complex elastic modulus E ^* 2 of the rubber of the second land portion. When the tread rubber is formed of a plurality of layers (for example, cap rubber and base rubber), the complex elastic modulus E ^* 1 and E ^* 2 are complex in the rubber (for example, cap rubber) of the outermost layer in the tire radial direction. It is defined as the modulus of elasticity.

Thereby, the rigidity reduction of the first land portion can be suppressed without being influenced by the size, the number of formations, and the like of the resonators H. For that purpose, the difference ΔE ^* between the complex elastic modulus E ^* 1 and the complex elastic modulus E ^* 2 is preferably 5.0 MPa or more. The upper limit of the difference ΔE ^* is preferably equal to or less than 20 MPa, and when it exceeds 20 MPa, the noise reduction effect is reduced.

The complex elastic modulus E ^* is a value measured using a “viscoelasticity spectrometer” under the conditions shown below according to the definition of JIS-K6394.
Initial strain (10%),
・ Amplitude (± 1%),
Frequency (10 Hz),
・ Deformation mode (tensile),
Measurement temperature (70 ° C.).

  Here, the volume V of the hollow portion 10, the cross-sectional area S of the communication hole 13, and the length L of the communication hole 13 are appropriately set in order to obtain a desired natural frequency f. However, since the resonator H needs to be formed inside the land portion 4, the volume V, the cross-sectional area S, and the length L have limitations.

For example, if the volume V of the hollow portion 10 is too large, problems occur in the rigidity of the tread portion 2 and releasability after vulcanization, and when it is too small, the muffling effect is reduced. If the cross-sectional area S of the communication hole 13 is too large, the adhesion friction when the air K1 of the communication hole 13 vibrates becomes small, and the muffling effect is reduced. Conversely, if the cross-sectional area S is too small, the resonator H will not function sufficiently. If the length L of the communication hole 13 is too long, the rigidity and the muffling effect are reduced, and if the length L is too short, the muffling effect is reduced. From such a viewpoint, the volume V of the cavity portion 10 is preferably in the range of 20 to 4000 mm ³ . The cross-sectional area S of the communication hole 13 is preferably in the range of 1.5 to ²⁰ mm ² . The length L of the communication hole 13 is preferably in the range of 2 to 50 mm.

  FIG. 6 shows another embodiment of the tire 1. In the tire 1 of this example, each land portion 4 is divided into a plurality of blocks 7 aligned in the tire circumferential direction by the lateral groove 6 crossing the land portion 4. Then, for example, the muffling means 5 is formed in at least one of the blocks 7 disposed in the middle land portion 4M. In the present example, the cavity portion 10 and the first sipe 8 are inclined at an angle of, for example, 45 to 90 degrees with respect to the tire circumferential direction line. Further, the first sipe 8 traverses the middle land portion 4M (block 7), and both ends thereof are opened by the main grooves 3C and 3S. Reference numeral 15 in FIG. 1 denotes a sipe, which in this example is formed on the center land portion 4C, the middle land portion 4M, and the shoulder land portion 4S, and in cooperation with the first sipe 8, the wet performance of the tire 1 , And improve the performance on ice. A three-dimensional sipe 12 may be suitably employed as the sipe 15, but a two-dimensional sipe or a flat sipe may be employed which extends linearly in the depth direction.

  In the present embodiment, the middle land portion 4M is provided with the muffling means 5, but the present invention is not limited to this, and the muffling means 5 can be provided on any one or a plurality of land portions 4.

  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 of illustration.

  A pneumatic tire (215 / 60R16) having the tread pattern shown in FIG. 1 and including the muffling means shown in Table 1 was made as an experiment, and the external noise performance and the wet performance were tested. Each tire has substantially the same specifications except those described in Table 1.

(1) Outside noise performance:
A new tire is mounted on all wheels of the vehicle under the following conditions, and the test course (ISO road surface) is run at a speed of 80 km / h with the engine off, at a distance of 7.5 m from the driving center line and from the road surface The maximum level dB (A) of passing noise was measured by a microphone installed at a height of 1.2 m. The result is indicated by a score that sets Comparative Example 1 to 100. The larger the value, the lower the noise and the better the external noise performance.
Rim: 16 x 6 J
Internal pressure: 230 kPa
Vehicle: Passenger car (1800cc displacement, FF car)

(2) Wet performance:
Using an inside drum tester, the rate of occurrence of hydroplaning phenomenon was measured when a tire with 50% wear was run under the following conditions. A result is displayed by the score which sets comparative example 1 to 100, and it is excellent in wet performance, so that a numerical value is large.
Rim: 16 x 6 J
Internal pressure: 230 kPa
Load: 4.8 kN
Water depth: Water depth 5.0 mm

  As shown in the table, it can be confirmed that the tire of the example can improve the external noise performance by reducing air column resonance noise caused by the main groove. Moreover, it can be confirmed that the tire of the example can improve the wet performance after 50% abrasion.

DESCRIPTION OF SYMBOLS 1 tire 2 tread part 3 main groove 4 land part 5 muffling means 8 first sipe 9 second sipe 10 hollow part 12 three-dimensional sipe 13 communicating hole C tire equator

Claims (13)

A tire comprising a main groove extending in the circumferential direction of the tire and a plurality of land portions divided by the main groove in a tread portion,
At least one land section is
A hollow portion which is substantially sealed inside the land portion and in which both longitudinal ends are interrupted inside the land portion;
Small hole communication that connects the cavity with the main groove through the inside of the land and has a cross-sectional area perpendicular to the longitudinal direction smaller than the cross-sectional area perpendicular to the longitudinal direction of the cavity With holes
A first sipe extending from the hollow portion to the tread surface of the land portion;
A tire comprising muffling means having a second sipe extending from the communication hole to the tread surface of the land portion. The noise reduction means has a volume V (mm ³ ) of the hollow portion, a cross-sectional area S (mm ² ) perpendicular to the longitudinal direction of the communication hole, and a length L (mm) of the communication hole The tire according to claim 1, which satisfies (1).
5.0 × 10 ⁻⁵ ≦ S / (V × L) ≦ 3.0 × 10 ⁻³ --- (1)   The tire according to claim 1 or 2, wherein one or more of the muffling means are disposed within a contact range where the tread portion contacts the road surface.   The communication hole is connected to the hollow portion at the connection position P, and the distance Lb from one end in the lengthwise direction of the hollow portion to the connection position P is 0.1 to 0. 1 of the length La of the hollow portion. The tire according to any one of claims 1 to 3, which is nine times as large.   The first sipe extends zigzag in the longitudinal direction in the horizontal cross section parallel to the tread surface, and extends in the depth direction in the vertical cross section perpendicular to the longitudinal direction line The tire according to any one of claims 1 to 4, which is a three-dimensional sipe.   The tire according to claim 5, wherein the three-dimensional sipe has a bending number n of zigzag in the vertical cross section of 2 or more.   The tire according to claim 5 or 6, wherein the three-dimensional sipe has a sipe depth Hs from the tread surface to the hollow portion of 2 mm or more.   The tire according to any one of claims 5 to 7, wherein the three-dimensional sipe has a zigzag amplitude Ws of 1.5 mm or more in the vertical cross section. The plurality of land portions are composed of a first land portion having the muffling means and a second land portion not having the muffling means, and the complex elastic modulus E ^* 1 of the first land portion is The tire according to any one of claims 1 to 8, which is larger than the complex elastic modulus E ^* 2 of the second land portion. The tire according to claim 9, wherein a difference between the complex elastic modulus E ^* 1 and the complex elastic modulus E ^* 2 is 5.0 MPa or more. Tire according to any one of claims 1 to 10 volume V of the cavity is in the range of 20~4000mm ^3. The tire according to any one of claims 1 to 11, wherein a cross-sectional area S of the communication hole is in a range of 1.5 to ²⁰ mm2.   The tire according to any one of claims 1 to 12, wherein a length L of the communication hole is in a range of 2 to 50 mm.

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