JPH03276802A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce the noise level at the time of grounding without causing the reduction of the wet performance by providing at least one or more fin sections which are protruded to close a main groove and elastically deformable in the axial direction of the main groove in each main groove located on a tread section. CONSTITUTION:Four main grooves 14 are formed in the peripheral direction of a tire 10 at a preset interval in the tire width direction of the tread section 12 of the pneumatic tire 10. Fin sections 16 are provided on each main groove 14 formed in the peripheral direction. End sections 20A, 22A of a pair of the right fin 20 and the left fin 22 provided across the axis 15 of the main groove 14 are fixed to wall faces 14A, 14B of the main groove 14 respectively, and the right fin 20 and the left fin 22 can be elastically deformed in the direction 15 of the main groove 14. When the pneumatic tire 10 is run on the dry road surface, most of the air flowing in an air column formed by the road surface and the main groove 14 is stemmed by the right fin 20 and the left fin 22. The noise level at the time of grounding due to the resonance phenomenon of the air column can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a tread portion with a plurality of main grooves along the tire circumferential direction.

[Conventional technology]

Conventionally, in order to improve the wet performance of a tire, especially the anti-hydroplaning performance, a plurality of main grooves 7 are provided in a tread portion 72 along the tire circumferential direction, as shown in FIG.
A pneumatic tire 70 is known in which a main groove 74 is formed so that water entering the ground contact surface is quickly drained away through a main groove 74.

Particularly in recent high-performance pneumatic tires, as the tires become flatter, hydroplaning is extremely likely to occur. For this reason, the width N of the main groove 74 is set to be quite large.

However, when the width N of the main groove 74 is set large, the air column formed by the road surface and the main groove 74 becomes thick. Due to this, there was a problem in that the noise level at the time of ground contact caused by the resonance phenomenon of these air columns increased.

[Problems solved by the invention]

The present invention has been made in consideration of the above facts, and an object of the present invention is to obtain a pneumatic tire that can reduce the noise level upon contact with the ground without causing a decrease in wet performance.

[Means to solve the problem]

The present invention as set forth in claim (1) is a pneumatic tire having a plurality of main grooves along the circumferential direction of the tire in a tread portion, wherein the tread portion has a contact surface under a normal internal pressure and under a normal load. It is characterized by having at least one fin part in each of the main grooves existing in the ground, which protrudes so as to close the main grooves and is elastically deformable in the axial direction of the main grooves.

Further, in the present invention as set forth in claim (2), the ratio W/D of the step difference W between the opening side end of the main groove and the fin portion and the depth D of the main groove is 0. It is characterized by being set to 1 to 0.5.

Further, the present invention as set forth in claim (3) is characterized in that the thickness of the fin portion in the tire circumferential direction is set to be equal to or less than the width of the main groove.

Further, the present invention as set forth in claim (4) is characterized in that the fin portion is constituted by a pair of fins provided on both sides of the center line of the main groove.

Further, in the present invention as set forth in claim (5), the fin portion is constituted by a pair of fins provided one on each side of the main groove, and each fin is on the center line side of the main groove. It is characterized in that the end portions are provided so as to overlap with each other with a gap in the tire circumferential direction.

[Effect]

In the present invention as set forth in claim (1), at least one fin portion is present in each main groove existing in the ground contact surface under normal internal pressure and normal load of the tread portion, and the fin portion closes the main groove. The fin portion protrudes like this, and this fin portion can be elastically deformed in the axial direction of the main groove.

Therefore, when the pneumatic tire of the present invention runs on a dry road surface, most of the air flowing in the air column formed by the road surface and the main groove is stopped by the fins. As a result, the air flow rate decreases and the air flow becomes turbulent. Thereby, the resonance phenomenon of the air column can be suppressed, and the noise level at the time of ground contact caused by the resonance phenomenon can be reduced.

Further, when the pneumatic tire of the present invention runs on a wet road surface, the hydraulic pressure of the water flowing between the road surface and the main groove is considerably higher than the air pressure of the air flow, so this hydraulic pressure causes the fins to It is elastically deformed in the axial direction of the main groove, that is, in the direction in which hydrodynamic pressure is applied.

Therefore, the water flow flowing between the road surface and the main groove is not blocked by the fins, and water entering the ground contact surface can be quickly drained away by the main groove. For this reason,
No deterioration in wet performance.

On the other hand, if there is no step between the opening end of the main groove and the fin,
In other words, if the height of the fin is the same as the tire surface, when the fin touches the ground, a striking sound will be generated at the stepping part, and the sound will be harsh depending on the frequency determined by the tire rotation speed and the pitch of the fin. May produce noise.

Therefore, in the present invention as set forth in claim (2), the fin height is not the same as the tire surface, and the ratio of the step W between the opening side end of the main groove and the fin to the depth D of the main groove is W/D from 0.1 to 0.
5 to prevent the generation of impact noise at the stepping part when the fin touches the ground.

Note that the ratio W/D is 0.1 to 0. It is preferable to set it to 5, and W/D is 0. If it is less than 1, the fin may touch the ground due to compressive strain in the tire radial direction at the trend section under the normal load, causing a harsh sound.
If it exceeds 0.5, the resonance phenomenon of the air column will be insufficiently suppressed.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

As shown in FIG. 3, in the tread pattern of the tread portion 12 of the pneumatic tire 10, the width direction of the tire (
Four main grooves 14 are formed in the circumferential direction of the tire (vertical direction in FIG. 3) at predetermined intervals in the horizontal direction in FIG. 3). Two of these circumferential grooves 14 are formed near the equatorial plane 13 of the tread portion 12 with the equatorial plane 13 in between,
The other two are formed near both ends in the tire width direction of the ground contact area S (corresponding to the actual tread width) of the tread portion 12 under normal internal pressure and normal load.

Furthermore, each circumferential groove 14 is provided with a fin portion 16 . This fin portion 16 is provided so that at least one fin portion 16 is present in each circumferential groove 14 on the contact surface 18 of the pneumatic tire IO under normal internal pressure and normal load as shown in FIG. There is.

Note that the fin portions 16 may be formed to be shifted in the tire circumferential direction for each main groove 14, and the pitch of the fin portions 16 in the tire circumferential direction may also be changed for each main groove 14.

As shown in FIGS. 1 and 2(A), the fin portion 16 includes a right fin 20 disposed across the axis 15 of the main groove 14,
The left fin 22 is considered to be a pair. One end 2OA of the right fin 20 is fixed to or integrally formed with one wall surface 14A of the main groove 14. Further, one end 22A of the left fin 22 is fixed to or integrally formed with the other wall surface 14B of the main groove 14. The other end 2 of the right fin 20
A gap is formed between 2A and the other end 22B of the left fin 22. Therefore, as shown by the imaginary lines in FIG. 2(A), the right fin 20 and the left fin 22 are elastically deformed in the direction of pressure application (in the direction of arrow V) when a pressure of a predetermined value or more is applied, and the right fin 20 and the left fin 22 are opened double-sided. It is designed to be. Also,
The thickness T of these right fin 20 and left fin 22 is the same as that of the main groove 1.
4 (T≦L).

As shown in FIG. 2(B), the opening side end 1 of the main groove 14
4C (tire surface) and the right fin 20 and left fin 22, respectively, have a step W/D with respect to the depth D of the main groove 14, =
It is set between 0.1 and 0.5.

Next, the operation of this embodiment will be explained.

In this embodiment, the ends 2OA, 22 of the right fin 20 and the left fin 22 are provided as a pair with the axis 15 of the main groove 14 in between.
A is fixed to the wall surfaces 14A and 114B of each main groove 14, respectively, and the right fin 20 and left fin 22 are elastically deformable in the direction of the axis 15 of the main groove 14.

Further, these right fin 20 and left fin 22 are connected to the ground plane 18.
At least one pair of main grooves 14 are provided within the main groove 14 .

Therefore, when the pneumatic tire 10 of this embodiment runs on a dry road surface, most of the air flowing within the air column formed by the road surface and the main groove 14 is blocked by the right fin 20 and the left fin 22. , the air flow rate decreases and the air flow becomes turbulent. Therefore, the resonance phenomenon of these air columns can be suppressed, and the noise level during ground contact caused by the resonance phenomenon can be reduced.

Further, the step W between the opening side end 14C of the main groove 14 and the right fin 20 and left fin 22 is W with respect to the depth D of the main groove 14.
/D=0.1 to 0.5. Therefore, when the tires are transferred, the right fin 20 and the left fin 22 do not touch the ground, and it is possible to prevent the generation of impact noise at the stepping portions of the right fin 20 and left fin 22.

On the other hand, when the pneumatic tire 1o of this embodiment runs on a wet road surface, the hydraulic pressure of the water flowing between the road surface and the main groove 14 is considerably higher than the air pressure of the air flow, so that due to this hydraulic pressure, The right fin 20 and the left fin 22 are elastically deformed in the direction in which the hydrodynamic pressure acts (the direction of the arrow V in FIG. 2(A)), and the right fin 20 and the left fin 22 become double-sided.

Therefore, the water flow flowing between the road surface and the main groove 14 is
Since the main groove 14 is not blocked by the zero and left fins 22 and the water that enters the ground contact surface can be quickly drained away by the main groove 14, there is no deterioration in wet performance.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6.

Note that the same members as those in the first embodiment are given the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 5 and 6, the ends 24C and 126C on the bottom 14C side of the main groove 14 of the right fin 24 and the left fin 26 do not reach the bottom 14C of the main groove 14, respectively. This covenant,
A gap 27 is formed near the bottom 14C of the main groove 14. Further, the positions, thicknesses T, and steps W of the right fin 24 and left fin 2G are the same as those of the right fin 20 and left fin 22 of the first embodiment.

Therefore, by forming the gap 27, elastic deformation of the right fin 24 and the left fin 26 due to hydrodynamic pressure becomes smooth.

Moreover, this gap 27 hardly improves the noise level at the time of ground contact, which is caused by the resonance phenomenon of the air column.

Next, a third embodiment of the present invention will be described with reference to FIGS. 7 and 8.

Note that the same members as those in the first embodiment are given the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 7 and 8, the right fin 28 and the left fin 30 are formed by slits 29 along the depth direction of the main groove 14, respectively, in the upper portions 28A, 30A.

Divided into 3 parts (2
(It may be divided into four parts, etc.), and the lower part is 28C13.
0C(7) The bottom portions 14CffiJm of the main groove 14 do not reach the bottom portion 14C of the main groove 14, respectively. For this reason, main groove 1
A gap 31 is formed near the bottom 14C of 4. Also, the position, thickness T, and step W of the right fin 28 and left fin 30
are the same as the right fin 20 and left fin 22 of the first embodiment.

Therefore, the slit 29 allows the right fin 28 and the left fin 3 to
By dividing 0, the elastic deformation of the right fin 28 and left fin 30 due to hydrodynamic pressure becomes smooth. Moreover, the slit 29 and the gap 31 hardly increase the noise level at the time of ground contact, which is caused by the resonance phenomenon of the air column.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 9, 10(A), and 10(B).

Note that the same members as those in the first embodiment are given the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 9 and 10 (A), the fin portion 16
The main groove 140 is composed of a right fin 32 and a left fin 34 provided on both wall surfaces 14A and 14B, respectively. One end 32 of each of these right fin 32 and left fin 34
A and 34A are both wall surfaces 14A and 1.A of the main groove 14, respectively. IB
is fixed to or integrally formed with. On the other hand, the other ends 32B and 34B of these right fin 32 and left fin 34
overlap each other with a gap C in the tire circumferential direction.

Furthermore, as shown by the phantom lines in FIG. 10(A), the right fin 32 and the left fin 34 are configured to elastically deform in the direction of pressure application (in the direction of arrow V) when a pressure of a predetermined value or more is applied. It has become.

The gap C is smaller than 1/4 of the shortest length M in the tire circumferential direction of the main groove 14 (see Fig. 4) that exists in the contact surface of the pneumatic tire 10 under normal internal pressure and normal load (C<M/ 4)
It is set. In addition, Fig. 10 (A> and Fig. 10 (
As shown in B), the thickness T and the step W of the right fin 32 and left fin 34 are different from those of the right fin 2D and left fin 2 of the first embodiment.
It is considered to be the same as 2.

Therefore, when a pressure of more than a predetermined value acts on the right fin 32 and the left fin 34 in the direction of the arrow V, the right fin 32 and the left fin 34 move in the direction of the arrow V, as shown by the phantom line in FIG. 10(A). It opens in the direction.

Therefore, effects equivalent to those of the first embodiment can be obtained.

Next, the fifth embodiment of the present invention is shown in FIGS. 11 and 12 (A).
and will be explained according to FIG. 12(B).

Note that the same members as those in the first embodiment are given the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 11 and 12 (A), the fin 1
6 is one wall surface 14B of the main groove 14 (or the other wall surface 1
4A) is composed of a single fin 36.

One end 36A of this fin 36 is attached to the wall surface 14 of the main groove 14.
It is fixed to or integrally formed with B. On the other hand, each other end 36B of this fin 36 is connected to the other wall surface 1 of the main groove 14.
It has reached around 4A.

Therefore, as shown by the imaginary line in FIG. 12(A), the fin 36 is elastically deformed in the direction of the pressure (in the direction of arrow V) when a pressure of a predetermined value or more is applied.

Therefore, when a pressure of a predetermined value or more is applied in the direction of arrow V due to hydrodynamic pressure, the fins 36 open in the direction of arrow V, as shown by the imaginary line in FIG. 12(A).

Further, as shown in FIGS. 12(A) and 12(B), the thickness T1 and step W of the fin 36 are the same as those of the right fin 20 and left fin 22 of the first embodiment.

Therefore, effects equivalent to those of the first embodiment can be obtained.

In addition, in the fourth and fifth embodiments described above, the second
As in the embodiment, a gap may be provided near the bottom 14C of the main groove 14, and as in the third embodiment, each fin may be divided in the depth direction of the main groove 14.

Furthermore, as shown in FIGS. 13(A) and 13(B), the right fin 40.44 and the left fin 42.46 may be tilted in advance in the direction of action of hydrodynamic pressure (direction of arrow V). .

(Experiment example) In a passenger car tire with tire size 205/60R15 and four main grooves (straight group type tread) 14, the minimum length M on the contact surface of the four straight groups is 160M, and on the other hand, In the circumferential pinch 58, which is 0.36 times, the thickness T is 2ml1,
As shown in FIG. 1, a right fin 20 and a left fin 22 (
A test tire with a ratio of the step W to the depth D of the main groove 14 (W/D = 0.3) was manufactured as a prototype, and the sound pressure level was compared with that without fins, as shown in Figure 14. I got the results.

In this example, the opening width of each of the four straight groups was 7mm, and the depth D was 8mm.

From FIG. 14, 7007 to 1100H according to this invention
The reduction in sound pressure level near z is obvious.

〔Effect of the invention〕

Since the present invention has the above-described configuration, it has an excellent effect of reducing the noise level at the time of ground contact without causing a decrease in wet performance.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a fin of a pneumatic tire according to a first embodiment of the present invention, FIG. 2(A) is a plan view showing a fin of a pneumatic tire according to a first embodiment of the present invention, and FIG. Figure 2 (
B) is a sectional view taken along the line ■-■ of FIG. 2(A), FIG. 3 is a plan view showing the tread surface of the pneumatic tire according to the first embodiment of the present invention, and FIG. 4 is a cross-sectional view of the pneumatic tire according to the first embodiment of the present invention. FIG. 5 is a perspective view showing the fin of the pneumatic tire according to the second embodiment of the present invention;
FIG. 6 is a sectional view taken along the line Vl-Vl in FIG. 5, FIG. 7 is a perspective view showing the fin of a pneumatic tire according to a third embodiment of the present invention, and FIG. ■Cross-sectional view along the line,
FIG. 9 is a perspective view showing a fin of a pneumatic tire according to a fourth embodiment of the present invention, FIG. 10(A) is a plan view showing a fin of a pneumatic tire according to a fourth embodiment of the present invention, and FIG. 10
Figure (B) is a sectional view taken along the line X-X of Figure 10 (A),
FIG. 11 is a perspective view showing a fin of a pneumatic tire according to a fifth embodiment of the present invention, FIG. 12(A) is a plan view showing a fin of a pneumatic tire according to a fifth embodiment of the present invention, and FIG. 1
2(B) is a sectional view taken along the xn-xn line of FIG. 12(A), and FIGS. 13(A) and 13(B) are fins of a pneumatic tire according to another embodiment of the present invention. A plan view showing the part,
FIG. 14 is a graph showing the relationship between 1/3 octave center frequency and sound pressure level, and FIG. 15 is a plan view showing the tread surface of a conventional pneumatic tire. DESCRIPTION OF SYMBOLS 10... Pneumatic tire, 12... Tread part, 14... Main groove, 15... Axis line, 16... Fin part, 20.24.28.32... Right fin, 22. 26.3
0.34...left fin, 36...fin.

Claims (5)

[Claims] (1) A pneumatic tire having a plurality of main grooves along the circumferential direction of the tire in the tread portion, each of the main grooves existing in the contact surface under the normal internal pressure of the tread portion and the normal load. A pneumatic tire characterized by having at least one fin portion within a groove that protrudes so as to close the main groove and is elastically deformable in the axial direction of the main groove. (2) A claim characterized in that a ratio W/D of the step W between the opening side end of the main groove and the fin portion to the depth D of the main groove is set to 0.1 to 0.5. The pneumatic tire described in item (1). (3) The pneumatic tire according to claim 1, wherein the thickness of the fin portion in the tire circumferential direction is set to be less than or equal to the width of the main groove. (4) The pneumatic tire according to claim (1), wherein the fin portion is composed of a pair of fins provided on both sides of the center line of the main groove. (5) The fin portion is composed of a pair of fins, one on each side of the main groove, and the ends of each fin on the center line side of the main groove are spaced apart in the tire circumferential direction. The pneumatic tire according to claim 1, characterized in that the tires are provided in an overlapping manner.