JP2000233605A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce tire noises without deteriorating drainability of grooves formed on a tire tread part. SOLUTION: In a pneumatic tire provided with longitudinal block groups 2a and 2f in a tire shoulder region defined by grooves, longitudinal block groups 2b and 2e in a medium region and longitudinal block groups 2c and 2d in a tire center region, ptruding bodies 4a, 4b, 4c, 4d, 4e, 4f, 4g and 4h of a dynamic damper which absorbs vibrations with proper vibrations of blocks 3a, 3b, 3c, 3d, 3e and 3f are formed on the blocks 3a, 3b, 3c, 3d, 3e and 3f that constitute the longitudinal block groups 2a, 2b, 2c, 2d, 2e and 2f.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire and, more particularly, to a reduction in noise of a pneumatic tire when the vehicle runs.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made as techniques for reducing tire noise. For example, JP-A-5-13
No. 1813 discloses that the frequency of a columnar tube resonant sound formed by a road surface and a main groove of a tire at a tire contact portion is distributed to a number of frequencies by substantially continuously changing the length of the columnar tube. Thin plate-like projections are provided in each main groove of the tread pattern, and protrude in the transverse direction of the main groove. This thin plate-like projection causes a node of vibration in that part of the air column, that is, by dispersing a specific air column resonance frequency to a number of frequencies by changing the wavelength of the vibration, so-called white noise. Is used to reduce pattern noise.

[0003] Also, Japanese Patent No. 2521704 discloses that the height of the main groove is not higher than that of the tread by protruding from the bottom of the main groove in the direction of the tread.
It is proposed that a large number of protrusions are provided in the main groove, both sides being continuous with the groove side wall, the length of the groove in the groove width direction being longer than the length of the main groove in the longitudinal direction, and having a gap that is approximately bisected in the tire width direction. I have. Thus, noise is reduced by the same effect as that of the above-mentioned Japanese Patent Application Laid-Open No. 5-131813.

[0004]

As described above, all of the prior arts can prevent the generation of the columnar tube resonance noise formed in the tire tread groove and the road surface in the tire noise. A fin-shaped weir, such as a thin film plate or a protrusion, protrudes from the side wall of the groove that constitutes the column pipe, and forms a node of air column vibration with the weir to specify the length of the air column between the road surface (Contact length) is substantially changed to a large number of values to substantially prevent the occurrence of air column vibration.

However, when noise is measured by mounting a tire on an actual vehicle, unlike the bench test, there is almost no occurrence of columnar tube resonance in the tire tread, and the contribution to the tire noise is low. That is the fact.

In order to prevent the occurrence of columnar tube resonance noise, the number of weirs is generally required to be about 10 to 20 on the circumference of the main groove in the tire circumferential direction. The weir protruding from the wall reduces the drainage effect in the ditch, and also causes the braking performance and steering stability on wet roads to be impaired.

An object of the present invention is to provide a pneumatic tire capable of reducing tire noise in an actual vehicle.

Another object of the present invention is to provide a pneumatic tire capable of reducing tire noise without impairing drainage performance of a groove formed in a tire tread portion.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a pneumatic tire having a plurality of rows of tandem ribs or tandem blocks formed of grooves and grooves in a tire tread portion. A dynamic vibration absorber is formed on the ribs or blocks that constitute the group to absorb the vibration of the natural frequency of the rib or block, particularly the vibration of the natural frequency of the rib or block that vibrates in the direction along the tread surface. A pneumatic tire characterized in that:

[0010] The noise due to the vibration of the tire is caused by the fact that when the tire rotates and a rib or a block, which is a ground contact element of the tread portion, comes into contact with the road surface, a groove in the tread width direction or a groove forming a zigzag or block of the rib in the tread pattern. Discontinuous elements such as sipes and cuts generate an impact force between the road surface and the road surface, and the unevenness of the road surface collides with the tire to generate an impact force. Also, the frictional force generated between the surface of the rib or the block and the road surface, that is, the ground surface, is caused by a repulsive force based on rapid release due to the tire rotating away from the road surface. These impact or repulsion forces vibrate the tread blocks or ribs themselves, and generate noise. Therefore, suppressing these vibrations leads to a reduction in tire noise. There are two ways to suppress vibration. One is a method of weakening the impact force, and the other is to reduce the vibration of the tread element that has received the impact force by an appropriate buffering method,
It is a method of converting into heat and absorbing it. The present invention employs the latter method.

By the way, as one of the vibration damping methods for suppressing the vibration of the vibrating body and not as a noise source, there is a method of adding a dynamic vibration absorber to the object. This is effective when another vibration suppression system is difficult to use and the frequency of the target vibration is specified. That is, when an additional mass having a natural frequency corresponding to the natural frequency of the target vibrating body is given, only the frequency has a vibration damping effect. Therefore, it is generally considered that this method cannot be used for tire vibration sounds over a wide frequency range.

However, the inventor of the present invention joined the mass of the same material as the dynamic vibration absorber to the block or rib side wall of the tire tread, and considered the high viscoelasticity of rubber and the shape and dimensions. By constructing the mass that becomes the dynamic vibration absorber, for example, the protruding body of the dynamic vibration absorber in a form that absorbs the vibration of the natural frequency determined by the size, shape, material, etc. of the block or rib, a remarkable vibration damping effect is exhibited. I found to do.

That is, when a rib or a block on the tire surface collides with a road surface or is suddenly released from a deformed state due to a load, the rib or the block has a natural frequency determined by the shape, dimensions, physical properties, and the like of each. Vibrates particularly strongly at the fundamental frequency of. The magnitude of the vibration at the natural frequency is determined by the number of rotations of the tire and the pitch of the tread pattern installed on the tire tread, which greatly contributes to the noise level (level) of the noise generated from the tire. It is expressed as a product of numbers, and is different from the natural frequency and has a wide range of frequencies (beyond 0 Hz even in the normal speed range of a vehicle, up to 20 Hz).
It has been found that the magnitude of the vibration sound (pattern excitation sound) having a frequency of up to 00 Hz is determined. That is, by reducing the magnitude of one frequency, it is possible to reduce the vibration of a wide range of frequencies that greatly contributes to the tire noise.

The dynamic vibration absorber can be expected to have an effect only at a specific frequency such as at the time of resonance between the natural frequency of the dynamic vibration absorber and the vibration frequency of the main vibration system. Therefore, conventionally, a dynamic vibration absorber has not been used for reducing the pattern excitation sound which is a main factor of the tire noise.

However, in the present invention, since the relationship between the vibration of the rib or the block and the pattern excitation sound has been found, the dynamic vibration absorber having a vibration damping effect only at a specific frequency of the auxiliary vibration system has a frequency of It has been found that it is possible to effectively cope with the suppression of the pattern excitation sound that changes over a wide range, that is, the reduction of tire noise. Further, the frequency of the pattern excitation sound in a wide range is about 400 Hz to 700 Hz for a truck / bus tire and about 600 Hz for a light truck tire, which is the most remarkable one of the natural frequencies under a tire load condition. When the tire resonates with a natural frequency of about 900 Hz to 1200 Hz in a passenger car tire, a larger noise is radiated from the tire. However, as described above, the original vibration of the rib or the block is reduced by the dynamic vibration absorber. Since the magnitude has already been reduced, the magnitude of the vibration at the time of resonance also decreases.

Since the present invention is as described above, the direction along the surface of the tread portion due to the repulsive force based on the sudden release of the impact force or the frictional force received from the impact on the road surface is applied to the rib or the block when the vehicle is actually running. Because the dynamic vibration absorber provided as the auxiliary vibration system absorbs the vibration of the natural frequency of the rib or block that vibrates in the above manner, the vibration of the frequency that varies in a wide range in proportion to the tire rotation speed appearing as tire noise. Strength can be reduced. In other words, by forming a dynamic vibration absorber capable of responding only to vibration of a specific frequency on the ribs or blocks of the tread, even if the frequency of vibration changes widely due to changes in the tire rotation speed, the dynamic vibration absorber can already respond Wow, 1
Since the vibration is reduced in the natural frequency region determined by the three shapes, dimensions, and material properties, the vibration is effectively suppressed and the tire noise can be significantly reduced as compared with a tire without a dynamic vibration absorber.

The present invention is not a technique for preventing columnar tube resonance vibration generated in the main groove. Rather, the vibration of the natural frequency of the block or rib itself is absorbed by the dynamic vibration absorber of the auxiliary vibration system, and the noise is reduced as noise. Since the vibration that appears is reduced and the vibration is reduced, the tire tread can cope with the design without providing any protrusions such as weirs that impede the drainage of the main groove and the sub groove. Tire noise can be reduced without reducing the drainage effect of the groove formed in the portion.

The location of the dynamic vibration absorber is not particularly limited. However, in order to make the dynamic vibration absorber more responsive to the vibration direction of the block or rib (along the surface of the tread), at least one of the rib or the block is required.
Preferably, it is provided on one of the side walls. Further, by providing a dynamic vibration absorber on the other side wall, it is possible to cope with vibrations in any direction along the tread surface of the rib or the block.

It should be noted that if the size, shape, or material properties of the dynamic vibration absorber differ, the frequency to be reduced also differs. Therefore, for example, when the protrusions of the dynamic vibration absorber having a plurality of dimensions are joined to the side wall, the vibration, that is, the noise level can be more effectively reduced. For the same reason, it is also possible to form a plurality of dynamic vibration absorbers in the depth direction of the side wall of the rib or the block in accordance with the frequency to be reduced.

Further, the projection as a dynamic vibration absorber may be formed at the bottom of a depression formed on the side wall of the rib or the block or inside the opening hole opened on the surface of the rib or the block. In such a case, the amount of protrusion into the groove is reduced, and the drainage of the groove is not hindered. In the case where the above-mentioned depression or opening hole is adopted, the amount of protrusion of the dynamic vibration absorber as the protrusion is set to “0” from the side wall surface of the rib or the block or the surface of the rib or the block.
Alternatively, it can be "-". That is, the length of the projecting body of the dynamic vibration absorber can be made equal to or smaller than the depth of the depression or the opening. When such a configuration is adopted, a more favorable effect on drainage properties can be obtained. In particular, a narrow groove such as a slit is more effective.

Depending on the design conditions, it is preferable to increase the number or the mass of the protruding bodies as the dynamic vibration absorber, so that the volume of the blocks or ribs should be reduced in that case. There is
A preferable upper limit is set in terms of wear resistance, and a preferable lower limit is set in terms of dynamic vibration absorption effect. As a result of diligent examination of such points, in the case of a projecting body of a dynamic vibration absorber, when the total volume of the ribs or blocks constituting one column rib group or one column block group is M, the projecting body of the dynamic vibration absorber Total volume m
Has been found to be preferably in the range of 0.01M <m <0.20M. When the total volume m of the protrusions of the dynamic vibration absorber is 0.01 M or less, it is not preferable from the viewpoint of the effect of dynamic vibration absorption. When the total volume m of the protrusions of the dynamic vibration absorber is 0.20 M or more, the block or The volume of the rib is too low, which is not appropriate in terms of wear resistance.

By the way, in the tread having the block pattern, the portion where the contribution of the vibration noise is the largest is the block or rib in the tire shoulder region including the shoulder contact end. This is because those vibrations are transmitted to the tire sidewall portion and are easily expressed as sound.
Since the vibration from the tire center region has a long distance on the sidewall portion and is attenuated on the way, the contribution is small. Therefore, it is preferable that the projecting body as the dynamic vibration absorber is formed on the vertical ribs or the vertical block group in the shoulder region on the outer side in the tread width direction including at least the shoulder contact end of the tire tread portion. Further, it is preferable that the buttress portion is formed on the outer wall of the column rib or the column block group in the shoulder region constituting the buttress portion.

The dynamic vibration absorber of the present invention is not particularly limited, but is preferably constituted by a protrusion that forms a part of a rib or a block. In addition, the cross-sectional shape of the protrusion is larger in the tire radial direction than in the tread circumferential direction so that its own vibration is easily excited by vibration in the direction along the tread surface of the rib or block. Is preferred.

The sectional shape of the projection of the dynamic vibration absorber of the present invention is not limited to a rectangle. In short, the shape of the dynamic vibration absorber,
The dynamic vibration absorber may be designed so that the natural frequency determined by the dimensions and the material characteristics substantially matches the natural frequency of the rib or the block as the vibration damping object. The target frequency of the present invention is a natural frequency of a rib or a block in a direction along a tread surface of approximately 250 Hz to 6000 Hz or a normal speed range of a vehicle from 0 Hz to 0 Hz to 2000 Hz (over 0 Km / h. (Up to about 120 km / h), a frequency proportional to the product of the number of pattern pitches and the tire peripheral speed, and 800 Hz to 4000 H, which is one component of vibration based on slip between the tread surface and the road surface during acceleration running.
z.

In the present invention, since the natural frequency of the rib or the block differs depending on its size, shape and direction of load, it is necessary to design the dynamic vibration absorber accordingly. Therefore, the size and shape of the protruding body of the dynamic vibration absorber vary depending on the purpose. However, the design method can be performed in the same manner as that of a general dynamic vibration absorber.

That is, in order for the dynamic vibration absorber to work effectively, the design conditions must be brought close to the following two optimum values. Optimal frequency ratio The optimal frequency ratio is determined by the natural frequency ω _M along the circumferential direction of the rib or block and the natural frequency ω _m of the dynamic vibration absorber to be added.
(Ω _m / ω _M ), and if this is A ₀ , A ₀ =
1 / (1 + μ). Here, μ = m / M, where M is the equivalent mass of the rib or the block, and m is the equivalent mass of the protrusion of the dynamic vibration absorber. The equivalent mass is virtually concentrated at the tip of the beam because both the rib or block and the protrusion of the dynamic vibration absorber are distributed in the vibrating body itself like a cantilever. Oscillating motion as a smaller mass occurs. Therefore, the equivalent mass is smaller than the actual mass and acts equivalent to a large distributed mass. If the mass is evenly distributed (if the protrusion is a dynamic vibration absorber, its cross-sectional shape and dimensions are uniform), its equivalent mass is approximately 0.24 × actual mass.

Optimum Material Properties (Optimal Attenuation Ratio) The required optimal attenuation ratio “ζ ₀ ” is given as ζ ₀ = [3μ / 8 (1 + μ) ³ ] ^0.5 if “μ” is determined. . On the other hand, the damping ratio “ζ” of the designed tire is ζ
= C / 2m (k / M) ^0.5 , these M,
m, K, designed by combining C, "zeta" is that it is sufficient to approach the "zeta _0". Here, “K” is the rigidity (spring constant) per unit displacement of the rib or block to which the dynamic vibration absorber is to be added along the tread surface and in the direction of vibration to be reduced, and “C” is the rib or block. It is a damping (viscosity) coefficient of the rubber material constituting the protrusion of the dynamic vibration absorber of the block.

Ω _m = (k / m) ^0.5 , ω _M =
(K / M) Since it is ^0.5 , “ω _M ” is about 250H depending on the pattern design method, rubber material, tire size, etc.
Any value will be taken between z and 6000 Hz,
Generally 300 to 90Hz for truck and bus tires
It is often around 0 Hz.

If ω _M is determined, A ₀ = ω _m / ω _M , so that ω _m = A ₀ · ω _M = ω _M / (1 + μ) is an appropriate value.
Here, “k” is the spring constant of the protruding body of the dynamic vibration absorber, and k
Since = given as 3EI / L ³ as a function of the geometry, using the "m" to fit "omega _m" of a suitable value may be determined its dimensions. That is, "E" is the modulus of the rubber material used, and a rubber material having a value of 3 MPa to 5.5 MPa is generally used. "L" is the length of the protrusion, and "I" is the second moment of inertia of the protrusion in the vibration direction.

In the above description, the mass ratio μ = m / M has its minimum value determined in terms of the effect of the dynamic vibration absorber and its maximum value determined in terms of tread wear, and is approximately 0.01 M <m <0.
20M, that is, 0.01 <μ <0.20. Within this range, the above-mentioned rib or block frequency ratio "A"
Takes a value of 0.83 to 0.99. Therefore, in the case of a truck / bus tire, the natural frequency required as a dynamic vibration absorber is 250 Hz to 900 Hz.

In the above, the damping (viscosity) coefficient, which is a rubber material characteristic, is such that the optimum damping ratio is 0.102 <ζ ₀ <
Since the 0.21, from equation damping ratio "zeta", at a zeta = zeta _0, but the appropriate value is determined as ^{_{C = 2ζ 0 (mKμ) 0.5}} , the value of "C" of the material characteristics Since the tire is determined in advance from the inherent characteristics of a tire such as wear, steering stability and braking / driving performance, there is usually no design flexibility. Therefore, the adjusting m, K, and μ in order to bring the damping ratio zeta be designed zeta _0.

[0032]

FIG. 1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic tire according to the present invention, and FIG. 2 is a schematic enlarged sectional view taken along line AB in FIG. FIG. 3 is a schematic enlarged sectional view taken along line CD in FIG. FIG. 4 is a schematic enlarged sectional view taken along line EF in FIG. FIG. 5 is a schematic sectional view around the tire shoulder region in FIG.

In the drawing, reference numeral 1 denotes a tire tread portion, and 2 denotes a main groove 5a, 5b, 5d, 5e or a narrow groove 5c extending in a circumferential direction in a zigzag manner on the surface of the tire tread portion 1 and a tire width direction inclined. Extending lateral grooves 6a, 6b, 6c, 6
This is a vertical block group arranged in the tire circumferential direction by sections d, 6e, and 6f. As shown in the figure, the column block group 2 includes, from both sides in the tire width direction toward the tire center, column blocks 2a, 2a in the tire shoulder region.
f, the vertical block groups 2b and 2e in the medium area and the vertical block groups 2c and 2d in the tire center area.

In the present embodiment, each of the blocks 3 of the tandem block group 2 vibrates in a direction along the surface of the tire tread portion 1 by a repulsive force based on an impact force or a sudden release of a frictional force from hitting a road surface. Body 4 of a dynamic vibration absorber that absorbs vibration of a specific frequency of the block 3
Are formed.

The projecting body 4 of the dynamic vibration absorber is constituted by a tongue-shaped vibration element which is longer in the radial direction than in the circumferential direction of the tire.
The outer edge located on the outermost side of the tire is lower than the tire surface, and the inner edge located on the innermost side of the tire is higher than the groove bottom. This can act as a vibration element. In particular, when the protrusion of the dynamic vibration absorber is configured so that the outer edge located on the outermost peripheral side of the tire is lower than the tire surface, the protrusion of the dynamic vibration absorber contacts a road surface when a new tire is used. Therefore, the necessary vibration is not disturbed. Also, even if the tires are worn evenly due to use and the vibration absorber projecting body comes into contact with the road surface and the vibration may be disturbed, the tread surface of the block or rib accompanying the progress of wear may occur. Since the rigidity in the direction along the direction increases, the noise caused by the vibration of the tire is reduced. Therefore, the extent to which the protrusion of the dynamic vibration absorber is lowered from the outer edge located on the outermost peripheral side of the tire depends on the rigidity of the block or rib in the direction along the tread surface due to the wear of the tire. Can set an appropriate value.

The vertical block group 2 in the tire center area
In FIGS. 1 c and 2 d, as shown in FIG. 1, the blocks 3 c and the side walls 31 c and 3 b of the block 3 d are arranged with the inclined narrow groove 5 extending in the tire circumferential direction in the tire center region.
1d, a part of the blocks 3c and 3d,
The protrusions 4c and 4d of the dynamic vibration absorber are formed so as to protrude. The protrusions 4c and 4d of the dynamic vibration absorber are shown in FIGS.
As shown in the figure, the side walls 31c and 31d are formed as protrusions inside the depressions 32c and 32d that have entered the block.

The vertical block groups 2b, 2 in the medium area
In FIG. 1e, as shown in FIG. 1, blocks 3b arranged in a medium area with a lateral groove 6 extending in the tire width direction interposed therebetween.
And, in the block 3e, protrusions 4b and 4e of the dynamic vibration absorber that form part of the blocks 3b and 3e and protrude into the lateral groove 6 are formed. The protrusions 4b and 4e of the dynamic vibration absorber are
As shown in FIG. 1 and FIG. 3, the protrusions are formed inside the recesses 32b, 32e that enter the block on the side walls 31b, 31e.

Column group 2 in the tire shoulder region
a and 2f, as shown in FIG. 1, a block 3a and a block 3f arranged across the lateral grooves 6a and 6f extending in the tire shoulder region in the width direction of the tire.
a, 3f are formed as protrusions 4a, 4f of the dynamic vibration absorber which project into the lateral grooves 6a, 6f. The projecting bodies 4a and 4f of the dynamic vibration absorber are, as shown in FIGS.
The side walls 31a and 31f are formed as protrusions inside the depressions 32a and 32f that have entered the block. In addition, the column block group 2 in the tire shoulder region
In FIGS. 1A and 2F, as shown in FIGS. 1 and 5, recesses 81a and 81b are also formed in the outer walls 8a and 8b of the buttress portion, and the protrusions of the dynamic vibration absorber as protrusions inside the recesses 81a and 81b. 4g and 4h are formed. FIG.
7 is a tire center line.

The projections 4a, 4b, 4
c, 4d, 4e, 4f, 4g, and 4h grasp each block 3a, 3b, 3c, 3d, 3e, and 3f as a main vibration system, and rapidly release an impact force or a frictional force received from an impact on a road surface. Blocks 3a, 3b, 3c, 3 that vibrate in the direction along the tread surface by the repulsive force based on
It is configured to absorb the vibration of the unique frequency of d, 3e, 3f as an auxiliary vibration system. Specifically, for example, in a truck / bus tire determined by the shape, dimensions and material of the ribs or blocks of the tread pattern, the vibration energy of the natural frequency of about 300 Hz to 900 Hz in the direction along the tread surface is absorbed. It consists of a protruding body of a dynamic vibration absorber of an auxiliary vibration system that can be used. Therefore, since the vibration energy is absorbed by the protruding body of the dynamic vibration absorber, the normal speed of the vehicle (beyond 0 km / h, which is determined by the pitch number of the pattern that determines the magnitude of the vibration and the rotation speed of the tire). Up to about 120km / h)
Over 2000Hz over a wide frequency range of 0Hz
The magnitude of the vibration up to z can be reduced over the entire range. Further, the latter reduction in the magnitude of the vibration is the most remarkable among the natural frequencies under the load condition of the tire.
z, light truck tires 600Hz-900H
z, the magnitude of the vibration at the time of resonance with the vibration of 900 Hz to 1200 Hz in the passenger car tire can be reduced, and the noise based on the vibration generated from the tire can be effectively suppressed.

Since the invention of this embodiment is as described above, the blocks 3a, 3b, 3c, 3d,
3e and 3f, the tread portion 1 is provided by a repulsive force based on an abrupt release of an impact force or a frictional force received from an impact on a road surface.
The blocks 3a, 3b, 3 vibrating in a direction along the surface
c, 3d, 3e, and 3f, the vibrations of the natural frequencies possessed by the protruding bodies 4a, 4b, 4c of the dynamic vibration absorber as the auxiliary vibration system.
Since 4d, 4e, 4f, 4g, and 4h absorb, a remarkable vibration damping effect can be exhibited. Moreover, even for a wide range of frequencies determined by the number of pitches of the pattern generated in the tire tread portion and the number of rotations of the tire, the strength of the original vibration source which determines the magnitude of the frequency is determined by the protrusion 4a of the dynamic vibration absorber. , 4b, 4c, 4d, 4e, 4f, 4g, and 4h, so that they can be simultaneously reduced.

Incidentally, the present invention is not limited to the tire of the above embodiment. For example, as shown in FIG. 6, a plurality of side walls 10 a, 10
b. In this case, the projecting body 9 of the dynamic vibration absorber can be configured as a projecting body projecting obliquely with respect to the main groove 11 extending in the tire circumferential direction. Further, a recess 10c that has entered the inside of the block 10 is formed on the side wall 10b of the block 10, and the protrusion of the dynamic vibration absorber as a protrusion protrudes inside the recess 10c in a direction orthogonal to the lateral groove 12. 9b can also be formed.

By forming the protrusions 9a and 9b of the dynamic vibration absorber as a plurality of protrusions in this manner, it is possible to cope with a plurality of vibration directions generated along the surface of the tread portion 1. In addition, a plurality of types of protrusions having different shapes and dimensions from each other can be formed in one block or one rib to cope with a plurality of vibration directions generated along the surface of the tread portion 1. Further, by forming the projecting body 9a of the dynamic vibration absorber projecting obliquely with respect to the main groove 11 or forming the projecting body 9b of the dynamic vibration absorber inside the recess 10c, the main groove 11 or the lateral groove 12 is formed. Tire noise can be reduced without impairing the drainage performance of the tire.

As shown in FIG. 7, a projection 15 of the dynamic vibration absorber formed on the side wall 13a of the block 13 on the side of the main groove 14 is provided.
May be formed on the inner wall 131a which is cut in a triangular cross section in the inner direction of the block 13. In the case of such a tire, tire noise can be reduced without further impairing drainage performance.

As shown in FIG. 8, the block 16 has an opening 17 formed in the surface 16a of the block 16.
The protrusion 18 of the dynamic vibration absorber along the direction of the surface 16a can be formed. Further, as shown in FIG. 8, a dent 20 is formed in the side wall 19 of the block 16 so as to enter the inside of the block 16, and one opening edge of both banks 21 a and 21 b constituting the inside of the dent 20. In the part 211b,
The projecting body 22 of the dynamic vibration absorber as a projecting body that forms a part of the side wall 19 and protrudes in a state where the depression 20 is substantially closed.
Can also be formed. Projection body 1 of any dynamic vibration absorber
8 and 22 can also reduce tire noise without further impairing drainage.

FIG. 9 shows a block 23 constructed by combining the protrusions of the dynamic vibration absorber. That is, on the side wall 25 of the block 23 on the side of the main groove 24, a protrusion 26 of a dynamic vibration absorber as a protrusion protruding in a direction orthogonal to the main groove 24 is formed inside the recess 25. Block 2
In the side wall 28 on the side of the lateral groove 27, a projection 30 of a dynamic vibration absorber as a projection that forms a part of the side wall 28 and protrudes in parallel with the lateral groove 27 in a state where the depression 29 is substantially closed is formed. I have. On the other side wall 32 of the block 23 on the side of the other lateral groove 31, a projection 34 of a dynamic vibration absorber as a projection projecting in a direction orthogonal to the lateral groove 31 is formed inside the recess 33. Furthermore, on the side wall 35 on the tire shoulder side of the block 23, a projection 37 of the dynamic vibration absorber as a projection is formed inside the depression 36.

Therefore, in the tire provided with the block 23, since the vibration directions of the protrusions 26, 30, 34, and 37 of the dynamic vibration absorber are all formed corresponding to the vibration in the tire circumferential direction, the road surface is particularly suitable. The vibration of the inherent frequency of the block, which vibrates the tread surface along the tire circumferential direction by the repulsive force based on the sudden release of the impact force or the frictional force received from the impact on the tire, is good without impairing drainage performance Can be absorbed.

In FIG. 10, the protrusions 3 of the two dynamic vibration absorbers
8, 39 are corner portions 41, 4 of the side wall of the block 40.
2 is formed. As a result, the tire provided with the protrusions 38 and 39 of the dynamic vibration absorber moves the tread portion surface in the tire circumferential direction and the tire width direction by a repulsive force based on an impact force or a sudden release of a frictional force received from impact on a road surface. The vibration of the specific frequency of the block vibrating along the ranges in both directions can be satisfactorily absorbed without impairing drainage.

Similarly, as shown in FIG. 11, the protrusion 45 of the dynamic vibration absorber is formed in the vertical groove 43 inclined with respect to the tire circumferential direction or the horizontal groove 44 inclined with respect to the tire width direction. Vibration in both the tire circumferential direction and the tire width direction can be effectively absorbed. This means that the same effect can be obtained by inclining only the protrusion 15 of the dynamic vibration absorber with respect to the groove, even if the groove is a straight line parallel to the circumferential direction or width direction of the tire as shown in FIG. You can get it. FIG. 11 is a schematic development view of a tread pattern showing another embodiment of the pneumatic tire according to the present invention, wherein 46 and 46 are center blocks, and 47 and 47 are shoulder blocks.

FIGS. 12 to 15 show some examples of the cross-sectional shape along the projecting direction of the projecting body of the dynamic vibration absorber. FIG. 12 shows the groove 50 from the depression 49 of the block 48.
Inside, a protruding body 51 of a dynamic vibration absorber that protrudes in an inverted trapezoidal cross section is shown. FIG.
The protrusion 55 of the dynamic vibration absorber that protrudes inside as a protrusion having a rectangular cross section is shown. FIG. 14 shows the depression 5 of the block 56.
7 shows a protrusion 58 of the dynamic vibration absorber that protrudes as a protrusion having a trapezoidal cross-section inside 7. FIG. 15 shows block 5
9 shows a protrusion 62 of the dynamic vibration absorber that protrudes from the depression 60 of FIG. 9 into the groove 61 as a rectangular protrusion having a large sectional width.

The shapes in which the tips 511 and 621 of the projecting bodies 51 and 62 of the dynamic vibration absorber are larger than the joining ends 512 and 622 to the ribs or the blocks as shown in FIGS. Although there are difficulties, the protrusions 51 and 6
Since the difference between the equivalent mass and the substantial amount of No. 2 can be reduced, if the wear volume of the rubber reduced by the setting of the dynamic vibration absorber is in the same range, it is advantageous in the vibration absorbing capacity.

The projecting body 58 of the dynamic vibration absorber shown in FIG.
Since the tip 581 is small and the joining portion 582 is large, the cross-section is substantially trapezoidal, so that the tire production is easy and the shape stability is excellent. The reduction in the volume effective for abrasion is increased. FIG. 13 shows the tip 5 of the protrusion 55 of the dynamic vibration absorber.
It has the same dimensions from 51 to the joint 552, and has an intermediate feature between the three. In the actual tire design, the cross-sectional shape of the protrusions of these dynamic vibration absorbers may be selected according to the design purpose, or according to the form of vibration acting on one tire. good.

It is to be noted that the dynamic vibration absorber as a protruding body may be appropriately rounded at the joint with the block or the rib in order to cope with the durability and crack resistance.

[0053]

EXAMPLE Table 1 with tread pattern shown in FIG.
A pneumatic tire having the following specifications is manufactured and mounted on all axles of a truck (2, 2, D type with a constant load of 10 tons), and the noise generated from the tire at various vehicle speeds is determined. The relationship between the frequencies was measured and evaluated by an inertial running test. For comparison, a tire identical to the tire of the above embodiment was manufactured except that the dynamic vibration absorber was not set and arranged, and the same test as the above embodiment was performed.

The tire shown in FIG. 16 has substantially the same tread pattern as the tire shown in FIG. 1. 63 is a tire tread portion, 64 is a surface of the tire tread portion 63, and a groove and a groove are formed. It is a group of tandem blocks arranged in the tire circumferential direction. As shown in the figure, the column block group 64 includes, from both sides in the tire width direction toward the tire center, column block groups 64a, 64a in the tire shoulder region.
4f, column block groups 64b and 64e in the medium area
And the vertical block groups 64c and 64 in the tire center area.
d respectively. This tire has a main groove 65 extending in the tire circumferential direction similarly to the tire of FIG.
a, 65b, 65d, 65e and the narrow groove 65c, and the lateral grooves 66a, 66b, 66c, 66d extending in the tire width direction.
66e and 66f. 67a and 67f are outer walls of the buttress portion 67, and TC is a tire center line.

As described above, the tire of FIG. 16 according to the embodiment has a tread pattern substantially similar to that of the tire of the first embodiment.
The tire shown in FIG. 16 differs from the tire shown in FIG.
The protrusions of the dynamic vibration absorber are installed only in the column blocks 64a and 64f in the tire shoulder region. That is, in the column block group 64a in the tire shoulder region, as shown in FIG.
A projecting body 681 of a dynamic vibration absorber, which projects in the same direction with respect to 6a, is provided for each block. In the vertical block group 64f in the tire shoulder region, the protrusions 68 of the dynamic vibration absorber project in the direction opposite to the protrusions 681 of the dynamic vibration absorber with respect to the lateral grooves 66f in the tire shoulder region.
2 is provided for each block. As shown in FIGS. 16 and 17, the projections 681 and 682 of these dynamic vibration absorbers are provided with shoulder blocks 69 on the side of the lateral grooves 66a and 66f.
In the side walls 70a, 70f of a, 69f, the recesses 71a, 71f are formed inside the block. The projecting bodies 681 and 682 of these dynamic vibration absorbers have a thickness of 4.5 mm, a projecting length of 0.5 mm, and a height of 12 mm. Also, the protrusions 681, 6 of the dynamic vibration absorber are used.
As shown in FIG. 17, reference numeral 82 denotes a tongue-shaped vibrating element which is longer in the radial direction than in the width direction of the tire, and an outer edge 681a located on the outermost peripheral side of the tire has a tire surface 72.
Lower than the inner edge 68 located on the innermost peripheral side of the tire.
1b is configured as a protrusion higher than the groove bottom surface 73.

The vertical block groups 64a and 64f in the tire shoulder region of the tire of this embodiment include
As shown in FIG. 18 and the outside wall 67 of the buttress portion 67,
The recesses 74a, 74f are also formed in the recesses 74a, 74f, and the projections 75a, 7 of the dynamic vibration absorber are provided inside the recesses 74a, 74f.
5f is formed. The projecting body 75a of this dynamic vibration absorber,
75f has a thickness of 4.5 mm, a projection length of 0.5 mm, and a height of 12 m, similarly to the protrusions 681 and 682 of the dynamic vibration absorber.
m. Further, the projecting body 75 of this dynamic vibration absorber
a and 75f are different from the tires shown in FIGS. 1 and 5 in that, as shown in FIG.
The planes 7a and 67f are almost flush with each other.

[0057]

[Table 1]

FIG. 19 shows the relationship between the frequency (Hz) of the 1/3 octave band and the noise level (dB (A)) at a vehicle speed of 60 km / h. A solid line indicates an example, and a dashed line indicates a comparative example.

As shown in FIG. 19, the tire of the embodiment in which the protruding body of the dynamic vibration absorber is arranged is 25 times larger than the tire of the comparative example.
It is recognized that the noise level is reduced with respect to the frequency of 0 Hz to 2000 Hz. In particular, the vibration frequency of the pattern around 300 Hz and the frequency where the most prominent peak appears at the natural frequency under the tire load state of 560 Hz are shown. The noise level has been significantly reduced at the two locations. The reason why the noise level is large in the latter is that one of the excitation frequency components due to the unevenness of the road surface resonates at this natural frequency, and the reduction effect is due to the unevenness and the tread surface of the rib or block. It can be said that the characteristic vibration in the direction along is close.

FIG. 20 shows the results of tire noise measured by the JASO C606 on-board noise test method using the same tires as in the above-mentioned Examples and Comparative Examples. The horizontal axis represents the vehicle speed (tire circumferential speed), and the vertical axis represents the tire speed. Is the overall level of noise at each speed. From FIG. 20, it can be seen that the noise level is reduced at all speeds, but the reduction effect is particularly large when resonating with 560 Hz which is the most remarkable natural frequency under a tire load state of 100 km / h. Can be

[0061]

As described above, in the pneumatic tire of the present invention, when the vehicle is running, the tread portion is formed on the rib or the block by the repulsive force based on the sudden release of the impact force or the frictional force from the impact on the road surface. Since the dynamic vibration absorber as the auxiliary vibration system absorbs the vibration of the specific frequency of the rib or block vibrating in the direction along the surface, a remarkable vibration damping effect can be exerted, and a wide range of vibration can be exhibited. Tire vibration noise can be reduced according to the frequency.

The pneumatic tire according to the present invention is not a technique for preventing columnar tube resonance vibration generated in the main groove, but has a configuration in which the main vibration of the block or the rib itself is released by the dynamic vibration absorber of the auxiliary vibration system. Therefore, since it is possible to cope with the design without providing a weir enough to inhibit drainage in the main groove, without reducing the drainage performance of the groove formed in the tire tread portion,
Tire noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic development view of a tread pattern showing one embodiment of a pneumatic tire according to the present invention.

FIG. 2 is a schematic enlarged sectional view taken along line AB in FIG.

FIG. 3 is a schematic enlarged sectional view taken along line CD in FIG. 1;

FIG. 4 is a schematic enlarged sectional view taken along line EF in FIG. 1;

FIG. 5 is a schematic sectional view around a tire shoulder region in FIG. 1;

FIG. 6 is a schematic perspective view of a unit block showing another embodiment of the pneumatic tire according to the present invention.

FIG. 7 is a schematic perspective view of a unit block showing another embodiment.

FIG. 8 is a schematic perspective view of a unit block showing another embodiment.

FIG. 9 is a schematic perspective view of a unit block showing another embodiment.

FIG. 10 is a schematic perspective view of a unit block showing another embodiment.

FIG. 11 is a schematic development view of a tread pattern showing the other embodiment.

FIG. 12 is a schematic cross-sectional view of a main part showing a protruding form of a protruding body of the dynamic vibration absorber.

FIG. 13 is a schematic cross-sectional view of a main part showing another protruding form of the protruding body of the dynamic vibration absorber.

FIG. 14 is a schematic cross-sectional view of a main part showing another protruding form of the protruding body of the dynamic vibration absorber.

FIG. 15 is a schematic cross-sectional view of a main part showing another protruding form of the protruding body of the dynamic vibration absorber.

FIG. 16 is a schematic development view of a tread pattern showing one embodiment of the pneumatic tire according to the present invention.

17 is an enlarged schematic cross-sectional view of a main part taken along line XX in FIG.

FIG. 18 is a schematic sectional view showing a protruding state of a protruding body of the dynamic vibration absorber on the buttress portion side according to the embodiment.

FIG. 19: Frequency (Hz) and noise level (dB (A))
6 is a graph showing a relationship with the graph.

FIG. 20 shows a tire peripheral speed (Km / h) and a noise level (d)
B (A)) is a graph showing the relationship.

[Explanation of symbols]

 Reference Signs List 1 tire tread portion 2 column block group 2a column block group in tire shoulder region 2b column block group in medium region 2c column block group in tire center region 2d column block group in tire center region 2e column block group in medium region 2f tire shoulder region Block group 3 block 3a block 3b block 3c block 3d block 3e block 3f block 31a side wall 31b side wall 31c side wall 31d side wall 31e side wall 31f side wall 32a dent 32b dent 32c dent 32d dent 32e dent 4f dent Projection body of dynamic vibration absorber 4b Projection body of dynamic vibration absorber 4c Projection body of dynamic vibration absorber 4d Projection body of dynamic vibration absorber 4e Projection body of dynamic vibration absorber 4f Projection body of dynamic vibration absorber 4g Projection body of dynamic vibration absorber 4 h Projection body of dynamic vibration absorber 5 Narrow groove 6a Lateral groove 6a Lateral groove 6b Lateral groove 6c Lateral groove 6d Lateral groove 6e Lateral groove 7 Tire center line 8a Outer side wall 8b Outer side wall 81a Depression 81b Depression 9 Side wall 10c c side wall of block 10a Depression 11 Main groove 12 Horizontal groove 13 Block 13a Side wall 131a Inner wall 14 Main groove 15 Projection body of dynamic vibration absorber 16 Block 16a Surface 17 Opening hole 18 Projection body of dynamic vibration absorber 19 Side wall 20 Depression 21a Bank 21b Bank 211b Opening edge 22 Projection body of dynamic vibration absorber 23 Block 24 Main groove 25 Depression 26 Projection body of dynamic vibration absorber 27 Side groove 28 Side wall 29 Depression 30 Projection body of dynamic vibration absorber 31 Horizontal groove 32 Side wall 33 Depression 34 Projection body of dynamic vibration absorber 35 Side wall 36 depression 37 Projection of dynamic vibration absorber 38 Projection of dynamic vibration absorber 39 Dynamic absorption Vibrator Projector 40 Block 41 Corner 42 Corner 43 Vertical Groove 44 Horizontal Groove 45 Projection of Dynamic Vibration Absorber 46 Center Block 47 Shoulder Block 48 Block 49 Depression 50 Groove 51 Projection of Dynamic Vibration Absorber 511 Tip 512 Joint End 52 Block 53 Depression 54 Groove 55 Projection of Dynamic Vibration Absorber 551 Tip 552 Joint 56 Block 57 Recess 58 Projection of Dynamic Absorber 581 Tip 582 Joint 59 Block 60 Recess 61 Groove 62 Projection of Dynamic Absorber 621 Tip 622 Joining End 63 Tire tread portion 64 Column block group 64a Column block group in tire shoulder region 64b Column block group in medium region 64c Column block group in tire center region 64d Column block group in tire center region 64e Length in medium region Row block group 64f Vertical block group in the tire shoulder region 65a Main groove 65b Main groove 65c Narrow groove 65d Main groove 65e Main groove 66a Lateral groove 66b Lateral groove 66c Lateral groove 66d Lateral groove 66e Lateral groove 66f Lateral groove 67 Buttress portion 67a Outer side wall 67f Outer side wall T Line 681 Projection body of dynamic vibration absorber 681a Outer edge 681b Inner edge 682 Projection body of dynamic vibration absorber 69a Shoulder block 69f Shoulder block 70a Side wall 70f Side wall 71a depression 71f depression 72 tire surface 73 groove bottom 74a depression 74f depression 74f Projection body of dynamic vibration absorber 75f Projection body of dynamic vibration absorber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B60C 19/00 B60C 11/06 A

Claims (11)

[Claims] 1. A pneumatic tire having a plurality of rows of tandem ribs or tandem blocks in a tire tread portion, the ribs or blocks constituting said tandem ribs or tandem block group. A pneumatic tire formed with a dynamic vibration absorber that absorbs the vibration of the natural frequency of the rib or block. 2. The pneumatic tire according to claim 1, wherein the dynamic vibration absorber is provided on at least one side wall of the rib or the block. 3. The pneumatic tire according to claim 1, wherein the dynamic vibration absorber is formed inside an opening hole opened on a surface including a side wall of the rib or the block. 4. The dynamic vibration absorber according to claim 1, wherein the dynamic vibration absorber is formed in a vertical rib or a vertical block group in a shoulder region of the tire tread portion at least in a tread width direction outside including a shoulder contact end. Pneumatic tire. 5. The pneumatic tire according to claim 4, wherein the dynamic vibration absorber is formed on an outer wall of a vertical rib or a vertical block group in a shoulder region constituting a buttress portion. 6. The pneumatic tire according to claim 1, wherein the dynamic vibration absorber is constituted by a protrusion that forms a part of a rib or a block. 7. When the total volume of ribs or blocks constituting one column rib group or one column block group is M, the total volume m of the projecting body of the dynamic vibration absorber is 0.01M <m <0. The pneumatic tire according to claim 6, which is in a range of 0.20M. 8. A recess formed in a side wall of the rib or the block, the recess being formed inside the rib or the block,
The pneumatic tire according to claim 6 or 7, wherein a projection of the dynamic vibration absorber is formed inside the depression. 9. The rib or block has a side wall formed with an inner wall cut out inside the rib or block, and the inner wall is formed with a projection of the dynamic vibration absorber. Pneumatic tires. 10. A recess formed in a side wall of a rib or a block, the recess being formed in the inside of the rib or the block. 8. The pneumatic tire according to claim 6, wherein a projecting body of the dynamic vibration absorber, which forms a part of the side wall surface, is formed so as to substantially close the side wall. 11. The pneumatic tire according to claim 6, wherein a plurality of types of dynamic vibration absorber protrusions having different shapes and dimensions are formed in one block or one rib.