JP4873514B2 - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce tire noises occurring outside a vehicle and prevent a tire from having uneven wear. SOLUTION: This pneumatic tire includes a plurality of longitudinal grooves 2 extending in the circumference direction R of the tire, on its tread surface 1. In at least one of the grooves, one or more protrusions are placed in the area including the position which is half the depth of the longitudinal groove in their width direction from both or either of the groove walls facing each other within the grounding length in the circumference direction of the tire under a reference load condition. The following equations are set: GP<GD, GP<GL, 0.4&times;GW<=GS<=0.8&times;GW, where GP represents the protruding length of the protrusion T in the width direction of the groove, GD represents the length of T in the depth direction of the groove, GL represents the length of T in the length direction of the groove, GS represents the clearance between the two protrusions T facing each other or between one protrusion T and the groove wall 3, and GW represents the width of the groove.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on a tread surface, and reduces noise generated during tire travel, and so-called uneven wear that occurs at the end of a land portion adjacent to the longitudinal groove. The present invention relates to a pneumatic tire for improving the tire.
[0002]
[Prior art]
The tire tread portion is likely to generate noise caused by vibration of air flowing in a cavity formed by the road surface and the longitudinal groove of the tire at the tire ground contact portion, that is, noise due to air column resonance during traveling of the vehicle.
[0003]
In addition, since the belt layer of a pneumatic tire with a radial carcass is provided with a highly elastic steel cord, the overall rigidity of the tire tread is high, and the rigidity of the tread with high rigidity is locally low. However, the end of the land adjacent to the vertical groove is easy to move during running of the tire, and the amount of slip between the land and the road surface increases and wear progresses, so that uneven wear, so-called river wear, is likely to occur.
[0004]
Conventionally, various proposals have been made to prevent such noise generation and uneven wear, but no invention has been proposed to improve both.
[0005]
[Problems to be solved by the invention]
An object of the present invention is a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface, reducing noise generated when the tire is running, and so-called uneven wear occurring at a land portion end adjacent to the longitudinal groove. It aims to improve riverware.
[0006]
By the way, in order to reduce the noise outside the vehicle of the tire, not only the air column resonance noise in the longitudinal groove but also the noise due to the pumping action, which is a large noise factor during the noise outside the vehicle, is effective. This is very important. That is, when the tire contacts the road surface, a vehicle load acts on the tire contact surface. In such a case, both the walls of the land portions located on both sides of the longitudinal groove are compressed by the ground and the longitudinal wall is compressed. It swells inside the groove and approaches to the point where the vertical groove closes. When the ground contact state is released along with the rotation of the tire, the bulge of the land portion returns to its original state due to the absence of load, and the cross-sectional shape of the predetermined vertical groove is restored. The compression to the vertical groove by the land portions on both sides and the release thereof are repeated so that air is sucked and discharged into the vertical groove and presents a so-called pumping state, which is the same as hitting the road surface by the tire pattern It becomes the frequency and overlaps and strengthens, and this becomes the largest contribution to the cause of noise outside the vehicle. In the conventional technology aiming at reducing the air column resonance noise, the effect of suppressing the pumping action is insufficient, and the effect of reducing the noise outside the vehicle as a whole is insufficient.
[0007]
An object of the present invention is to use not only air column resonance noise but also loud noise in the outside of a vehicle, using a protrusion protruding in the groove width direction from a groove wall of a longitudinal groove extending in the tire circumferential direction. It is an object of the present invention to provide a pneumatic tire that is also effective against noise caused by the pumping action and that can reduce the noise outside the tire as a whole and at the same time prevent uneven wear of the tire.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present invention provides:
In a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface,
Comprising at least one longitudinal groove, in the circumferential direction of the tire contact patch in length at the reference load condition, the half of the position of opposing the longitudinal groove depth from both sides of the groove wall of the groove walls to the groove width direction Arrange one or more pairs of opposing protrusions in the area,
The protrusion length in the protrusion groove width direction is GP,
The length in the groove depth direction is GD,
The length in the groove length direction is GL,
The gap between the projecting bodies facing each other in the vertical groove is GS,
The vertical groove width is GW
When
GP <GD, GP <GL, 0.4 × GW ≦ GS ≦ 0.8 × GW
The pneumatic tire which is is adopted.
[0009]
Accordingly, in the tire of the present invention, the depth of the vertical groove from the groove wall on both sides or one side of the opposite groove wall to the groove width direction is within the tire circumferential contact length in the reference load state in at least one vertical groove. One or more of the protrusions arranged in a region including 1/2 of the position of the vibration mode in the air column tube composed of the vertical groove and the road surface at the time of grounding intermittently or continuously from a specific frequency. Since the frequency changes, the air column resonance can be substantially eliminated.
In addition, the said reference | standard load state means the state which gave the air pressure prescribed | regulated to JIS specification and the load corresponding to it for every size of each tire.
Further, in the tire of the present invention, in at least one longitudinal groove, the longitudinal groove depth extends from the groove wall on both sides or one side of the opposing groove wall in the groove width direction within the tire circumferential contact length in the reference load state. Since one or more protrusions are disposed in the region including the position of 1/2 of the height, the movement of the land portion end adjacent to the vertical groove is suppressed. In other words, the vertical rigidity of the block is apparently increased, and as a result, the amount of slip between the block and the road surface at the end of the land portion is suppressed, thereby preventing the occurrence of uneven wear, so-called river wear.
[0010]
Further, in the tire of the present invention, in at least one longitudinal groove, the longitudinal groove depth extends from the groove wall on both sides or one side of the opposing groove wall in the groove width direction within the tire circumferential contact length in the reference load state. When the protrusions arranged at one or more places in the region including the half position are in contact with the tire, the opposing protrusions come into contact with each other . In such a case, the pumping frequency originally determined by the number of pitches of the tread pattern can be converted to a frequency determined by the arrangement interval of the protrusions in the tire circumferential direction at the time of load contact and can be randomized. Therefore, the pumping frequency does not coincide with the pitch number of the tread block pattern, and the pitch of the vibration sound generated by the vibration of the tire when the pattern hitting the road surface for each pitch, which has a large contribution to the outside noise of the tire. The primary peak level determined by the number can be reduced.
[0011]
The projecting length in the groove width direction is GP, the length in the groove depth direction is GD, the length in the groove length direction is GL, and the gap between the projecting bodies facing each other in the vertical groove. GS, when the vertical groove width is GW,
GP <GD, GP <GL, 0.4 × GW ≦ GS ≦ 0.8 × GW
The reason is that if at least one of the conditions of GP <GD or GP <GL is not satisfied, the projecting body is compressed when both the walls of the groove or one of the walls protrudes when the tire is loaded and the groove width is narrowed. This is because the projecting body is buckled, the narrowing of the groove width cannot be sufficiently suppressed, and the pumping action cannot be suppressed.
Further, the reason why the gap GS between the projecting bodies facing each other in the vertical groove is in the range of 0.4 × GW ≦ GS ≦ 0.8 × GW as described above is that the gap GS is less than 0.4 × GW. If the groove volume decreases, the drainage effect in the groove deteriorates, the running stability on the wet road is impaired, and if the gap GS exceeds 0.8 × GW, the narrowing of the groove width by the projecting body is sufficient. This is because it cannot be suppressed and the contribution to suppression of the pumping action is reduced, and as a result, the effect on noise reduction is lost.
[0012]
Moreover, the protrusion body from which the said tire circumferential direction length GL or width | variety GP differs in the same vertical groove can also be arranged. In this case, the rigidity of the protruding body is determined according to the pitch length of the groove walls where the protruding body is installed, that is, the magnitude of the force applied to the protruding body, thereby giving substantially the same apparent rigidity to the entire tread portion. Thus, noise can be suppressed more effectively, and the uniform wear state can be obtained from the uniformity of rigidity with respect to the load on the tread surface portion.
[0013]
It is more preferable that the projecting body is disposed in the tire radial direction on the same surface as the tread ground surface or on the inner side in the tire radial direction with respect to the tread ground surface and on the outer side in the tire radial direction with respect to the groove bottom surface. This is because, if the projecting body is on the outer side in the tire radial direction from the tread contact surface, the tip of the projecting body may be damaged by the external force acting at the time of grounding, or the base of the projecting body may be cracked. The effect of the projecting body is not sufficiently exhibited, and it tends to be a starting point of uneven wear, and the reason that it is located on the outer side in the tire radial direction from the groove bottom surface is to leave a passage for drainage at the bottom of the groove at the time of ground contact.
[0014]
In the same vertical groove,
The circumferential lengths of the adjacent protrusions in the tire circumferential direction are L1, L2,
The interval between the adjacent protrusions is LS,
The length of the tire ground contact circumference in the standard load state is L3
When
L1 ≦ LS <L3, L2 ≦ LS <L3
It is desirable that
[0015]
If the circumferential lengths L1 and L2 of the adjacent protrusions are larger than the interval LS between the adjacent protrusions, fluctuations in the pumping action of the groove suppressed by the protrusions may occur. This is also effective for noise suppression because it is affected and reduced even in the region of the interval LS between the two, but the volume in the groove is narrowed to reduce the water storage and drainage associated therewith. This makes the steering stability on a wet road, which is one of the above, unstable.
Further, when the distance LS between the adjacent protrusions is larger than the tire contact circumferential length L3 in the reference load state, there is a portion in which the protrusion does not intervene in the tire contact circumferential length during traveling. For this reason, air columnar resonance is generated, and generally the pumping action is not suppressed with respect to a pitch including a plurality of lengths in the contact circumferential direction, so that the effect on noise suppression is reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic tire according to the present invention. FIG. 2 is a schematic perspective view of a partial cross section taken along line AA in FIG.
[0017]
1 is a tire tread surface, 2 is a longitudinal groove that connects the tire tread surface 1 in the tire circumferential direction R, 3 is a groove wall of the longitudinal groove 2, 4 is a lateral groove, and 5 and 6 are grounding shoulder portions located on both sides of the tire, respectively. End, R is a tire circumferential direction, T is a projecting body, GS is a gap between projecting bodies projecting in the groove width direction from an opposing groove wall, L3 is a tire grounding circumferential length in a reference load state, 10 (dotted line) Is a tire circumferential direction grounding end in a reference load state.
[0018]
In the tire of the present embodiment, as shown in FIG. 1, the vertical groove 2 is composed of one vertical groove 2b, 2c on each side of the tire equator line CL, and further, vertical grooves 2a, 2d on both sides thereof. Has been. And the horizontal groove 4b is provided between the vertical groove 2b and the vertical groove 2c, and the central block 7b divided by this vertical groove 2b, the vertical groove 2c, and the horizontal groove 4b is arranged repeatedly in the tire circumferential direction. . On the other hand, a similar horizontal groove 4a is also provided between the vertical groove 2a and the vertical groove 2b, and a similar horizontal groove 4c is also provided between the vertical groove 2c and the vertical groove 2d. The intermediate blocks 7a and 7c divided by 2c and 2d and the lateral grooves 4a and 4c are repeatedly arranged in the tire circumferential direction. Note that shoulder ribs 8a and 8b extending in the tire circumferential direction are provided on both sides of the intermediate blocks 7a and 7c with the longitudinal grooves 2a and 2d interposed therebetween.
[0019]
Further, as shown in FIGS. 1 and 2, the tire according to the present embodiment has grooves from the side walls 31, 32, 33, 34, 35, 36, 37, and 38 of the longitudinal grooves 2a, 2b, 2c, and 2d. In the tire, protrusions T1, T2, T3, T4, T5, T6, T7, and T8 are provided in the width direction at unequal intervals along the tire circumferential direction. The vertical grooves 2a, 2b, 2c, and 2d have the same groove width in the portion where the protrusion T is not disposed, the groove width is GW, and the groove depth is the same depth D regardless of the presence or absence of the protrusion. is there. The protrusions T1, T2, T3, T4, T5, T6, T7, and T8 have the same shape, the protrusion length in the longitudinal groove width direction is GP, the circumferential length is GL, and the groove depth direction length is In GD, it is arranged in a region including a half point portion of GP <GD, GP <GL, and vertical groove depth D. Therefore, the gap GS between the protrusions is (GW-2GP).
[0020]
3A and 3B are schematic cross-sectional views taken along line AA in FIG. 1. FIG. 3A shows a non-grounded state, and FIG. 3B shows a grounded state. FIG. 4 is a schematic development view of a tread pattern when the protruding body is removed from the tire according to the present embodiment, and each reference numeral is the same as FIG.
5A and 5B are schematic cross-sectional views taken along the line BB in FIG. 4. FIG. 5A shows a non-grounded state, and FIG. 5B shows a grounded state.
[0021]
As can be seen from FIGS. 3A and 3B, in the longitudinal groove of the tire in which the protrusions T3 and T4 of the present embodiment are arranged, the gap between the protrusion T3 and the protrusion T4 when not grounded. However, at the time of grounding, the protrusion T3 and the protrusion T4 are in complete contact with each other, and the gap is eliminated. However, in the tire according to the present embodiment, the protrusion T3 and the protrusion T4 are not arranged to the groove bottom, so that the groove bottom side is continuous in the tire circumferential direction. On the other hand, in the case of the tire from which the protrusion is removed from the tire according to the present embodiment, as shown in FIGS. 5 (a) and 5 (b), the vertical groove is not grounded in the vertical groove. Although it is ensured, the vertical groove 33 and the vertical groove 34 are completely in contact with each other at the time of grounding, and the gap is eliminated. In addition, since the protrusions are not arranged as compared with the tire of the present embodiment, the vertical grooves 33 and the vertical grooves 34 are in contact with each other to the vicinity of the groove bottom, and there is almost no gap at the groove bottom.
[0022]
3 (b) and 5 (b) shows a schematic cross section of the longitudinal groove in FIGS. 3 (a) and 5 (a) when the tire is not grounded.
3 and 5, the tire according to the present embodiment in which the protrusions T3 and T4 are arranged in the vertical groove has less movement of the groove wall at the time of tire contact as compared with the tire without the protrusion. And it turns out that the space in the groove bottom is ensured. That is, in the case of the present embodiment, it is possible to ensure drainability even when the tire is running even if the above-described protrusion is provided.
[0024]
As described above, in the tire according to the present embodiment, the longitudinal grooves 2a, 2b, 2c, and 2d extending in the tire circumferential direction are within the tire circumferential direction ground contact length l3 in the reference load state. An air column in which one or more protrusions T arranged in one or more locations in a region including one half of the longitudinal groove depth in the groove width direction from the groove wall on one side are constituted by the longitudinal groove and the road surface at the time of ground contact Since the vibration mode in the tube is changed to a frequency that changes intermittently or continuously from a specific frequency, the air column resonance can be substantially extinguished.
[0025]
At the same time, in the tire according to the present embodiment, in at least one longitudinal groove, the ground contact length L3 in the tire circumferential direction R in the reference load state is within the groove width direction from the groove walls on both sides or one side of the opposed groove wall 3. In addition, one or more protrusions T are arranged in a region including a position of 1/2 of the vertical groove depth at which the maximum bulge deformation in the groove width direction of the vertical groove wall of the tread land portion occurs at the time of grounding. Therefore, the movement of the portion of the land portion end adjacent to the vertical groove 2 is suppressed. As a result, the amount of slip between the land portion and the road surface is suppressed, and uneven wear, so-called river wear, can be prevented.
[0026]
Further, in the tire according to the present embodiment, in at least one longitudinal groove 2, the tire circumferential direction ground contact length L3 in the reference load state corresponds to the groove width direction from the groove walls on both sides or one side of the opposed groove walls. When the projecting bodies T arranged at one or more places in a region including the position of 1/2 of the longitudinal groove depth are in contact with the tire, the opposing projecting bodies T or the projecting bodies T and the groove wall 3 come into contact with each other. In this case, the pumping frequency originally determined by the number of pitches of the tread pattern can be converted to a frequency determined by the arrangement interval of the protrusions T in the tire circumferential direction at the time of load contact and can be randomized. Therefore, the pumping frequency does not coincide with the frequency of the vibration sound associated with the tread on the road surface determined by the tread block pattern pitch number and the vehicle speed, that is, the tire rotation speed, and the pumping sound and the striking vibration sound strengthen. Therefore, it is possible to reduce the level of the primary peak frequency determined by the number of pitches of the pattern and the number of rotations of the tire that greatly contribute to the noise outside the vehicle.
[0027]
Therefore, the tire of the present invention can reduce the air column resonance noise generated between the longitudinal groove and the ground road surface and the pumping noise, and can effectively cope with the noise outside the vehicle. A pneumatic tire capable of preventing uneven wear can be provided.
[0028]
【Effect of the invention】
As described above, the present invention provides a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tire tread surface, and a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface.
In at least one longitudinal groove, within the tire circumferential contact length in the reference load state, a position of ½ of the longitudinal groove depth from the groove wall on both sides or one side of the opposing groove wall in the groove width direction. Arrange one or more pairs of opposing protrusions in the containing area,
The protrusion length in the protrusion groove width direction is GP,
The length in the groove depth direction is GD,
The length in the groove length direction is GL,
The gap between the projecting bodies facing each other in the vertical groove is GS,
The vertical groove width is GW
When
GP <GD, GP <GL, 0.4 × GW ≦ GS ≦ 0.8 × GW
Because it is a pneumatic tire, it can be effective not only for air column resonance noise, but also for noise due to pumping action, which is the cause of loud noise during tire exterior noise, as a whole It is possible to provide a pneumatic tire that can reduce noise outside the vehicle and can prevent uneven wear of the tire.
[Brief description of the drawings]
FIG. 1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic tire according to the present invention.
FIG. 2 is a schematic perspective view of a partial cross section taken along line AA in FIG.
3 is a schematic cross-sectional view taken along the line AA in FIG. 1. FIG. 3 (a) is a diagram showing a non-grounded state, and FIG. 3 (b) is a diagram showing a grounded state.
FIG. 4 is a schematic development view of a tread pattern when the protruding body is removed from the tire according to the embodiment.
5 is a schematic cross-sectional view taken along the line BB in FIG. 4. FIG. 5 (a) is a diagram showing a non-grounded state, and FIG. 5 (b) is a diagram showing a grounded state.
[Explanation of symbols]
1 tire tread surface 2 longitudinal groove 2a longitudinal groove 2b longitudinal groove 2c longitudinal groove 2d longitudinal groove 3 groove wall 31 groove wall 32 groove wall 33 groove wall 34 groove wall 35 groove wall 36 groove wall 37 groove wall 38 groove wall 4a transverse groove 4b transverse groove 4c Horizontal groove 5 Grounding end 6 of the shoulder portion Grounding end T of the shoulder portion Projection T1 Projection T2 Projection T3 Projection T4 Projection T5 Projection T6 Projection T7 Projection T8 Projection

Claims (4)

In a pneumatic tire having a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface,
Comprising at least one longitudinal groove, in the circumferential direction of the tire contact patch in length at the reference load condition, the half of the position of opposing the longitudinal groove depth from both sides of the groove wall of the groove walls to the groove width direction Arrange one or more pairs of opposing protrusions in the area,
The protrusion length in the protrusion groove width direction is GP,
The length in the groove depth direction is GD,
The length in the groove length direction is GL,
The gap between the projecting bodies facing each other in the vertical groove is GS,
The vertical groove width is GW
When
GP <GD, GP <GL, 0.4 × GW ≦ GS ≦ 0.8 × GW
A pneumatic tire characterized by being. The pneumatic tire according to claim 1, comprising protrusions having different lengths in the tire circumferential direction of the protrusions in the same longitudinal groove. The tire radial direction arrangement region of the projecting body is the same as the tread ground contact surface or the tread ground contact surface and the tire radial direction inner side and the groove bottom surface is the tire radial direction outer side. Pneumatic tire. In the same vertical groove,
The circumferential lengths of the adjacent protrusions in the tire circumferential direction are L1, L2,
The interval between the adjacent protrusions is LS,
The length of the tire ground contact circumference in the standard load state is L3
When
L1 ≦ LS <L3, L2 ≦ LS <L3
The pneumatic tire according to any one of claims 1, 2, and 3.

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