JPH0478604A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To reduce pattern noise without spoiling dry operation safety performance and hydro planing resistance performance by taking a measure of providing a bent part forming almost a V letter in a front view of an installation position of a tire to a car on a plural number of cross grooves provided on a tread part. CONSTITUTION:A plural number of cross grooves 2 extending in the tread cross direction and opening their both ends to grounding edges with intervals in the tire circumferential direction on a tread part 1. In this case, bent parts 3 extending in almost a V letter in the front view of the installation position of a tire to a car are provided in each of the cross grooves 2 in the central area of the tread part 1. Then, an intersection angle 01 of the bent parts 3 is made within the range of 25-60 deg., the formation territory of the bent parts 3 is made to be in the range of 30-80% of a tread breadth and a bent center 4 of the bent parts 3 is to be positioned within the range from a tread part central line a-a to 25% of the tread breadth. Additionally, a slight inclined part 5 which is larger than the intersectional angle of the bent parts 3 is provided on each of the cross grooves and it is inclined in the tread breadth direction at an angle 02 within the range of 30-70% against an extensional line of the bent parts 30.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a pneumatic radial tire with high maneuverability, and in particular, the present invention relates to a pneumatic radial tire with high maneuverability.
This effectively reduces pattern noise and provides excellent cabin comfort.

(Prior Art) Conventional high-performance pneumatic radial tires of this type have a combination of a plurality of circumferential linear grooves and a plurality of directional transverse grooves, as shown in Fig. 4, for example. These tires are generally tuned in various ways depending on the target performance.

In other words, if the wet drainage performance of the tire is important, the negative ratio should be set large, and if the hydroplaning resistance performance is important, the groove width of the circumferential straight groove should be set large, and the pattern noise should be reduced. In order to reduce pitch noise, it is necessary to reduce the pitch noise component caused by the collision of the stepping-in side and kick-out side of the ridge with the road surface by narrowing the groove width of the transverse groove or other means. It is being carried out according to

(Problem to be solved by the invention) By the way, if we pay particular attention to the reduction of pattern noise,
It can be roughly divided into noise brought about by the pattern pitch component and high frequency (around IKHz) noise caused by the air column resonance of the circumferential main groove. It can be effectively reduced by suppressing the road surface input to the stepping-in side portion and kick-off side portion. However, the latter noise is extremely difficult to reduce or eliminate because the circumferential main groove plays an extremely important role in ensuring wet drainage performance and anti-hydroplaning performance. Ta. In other words, although the sound pressure level of noise caused by air column resonance can be changed by changing the volume of the circumferential main groove, it is possible to change the sound pressure level of noise caused by air column resonance by changing the volume of the circumferential main groove. As long as it exists, even if the main groove width is narrowed, IK
It is impossible to prevent the generation of high frequency noise around Hz, and if the circumferential main groove is removed in order to prevent the generation of high frequency noise, wet drainage performance and hydroplaning resistance performance must be ensured. Or it was impossible.

The present invention advantageously solves the problems of the prior art, and by removing the circumferentially continuous main groove, the generation of high frequency noise is sufficiently prevented, and yet wet drainage performance and hydroplaning resistance are achieved. To provide a pneumatic radial tire that can extremely effectively prevent a decline in performance.

(Means for Solving the Problems) The pneumatic radial tire of the present invention has transverse grooves in the tread surface section extending in the tread width direction and opening at both ends or the ground contact end at intervals in the tire circumferential direction. A tire comprising a plurality of tires, in which each of the transverse grooves is provided with a bent portion that is approximately V-shaped when viewed from the front when the tire is mounted on a vehicle in the central area of the tread surface, and the bent portion is The bend intersection angle of the part should be in the range of 25 to 60 degrees, the forming area of the bend part should be in the range of 30 to 89% of the tread surface width, and the bending center of the bend part should be from the tread center line. in each said transverse groove, located within 25% of the tread width and in each side area of the tread tread;
A gently sloped portion is provided whose intersection angle with the center line of the tread portion is larger than that of the bent portion, and the gently sloped portion is tilted in the tread width direction within a range of 30 to 70° with respect to the extension line of the bent portion. It is something that

The second point will be explained in more detail based on the tread pattern illustrated in FIG.

Note that the internal structure of the tire is the same as that of a general radial tire, so illustration is omitted here.

In this example, a plurality of transverse grooves 2 extending in the tread width direction and opening at both ends or the ground contact end are provided at intervals in the tire circumferential direction on the tread surface l. In the central region, each transverse groove 2 is provided with a bending portion 3 extending in a substantially V-shape when viewed from the front when the tire is mounted on a vehicle, and the bending intersection angle θ1 of the bending portion 3 is as follows.
The range of 25 to 60' is set to 37 degrees in the figure, and the forming area of the bent portion 3 is set to 30 to 8 of the tread surface width.
0% range, for example, 53%, and furthermore, the bent portion 3
The bending center 4 of
-a, and furthermore, in each side region of the tread surface 1, each transverse groove extends continuously with the aforementioned bending portion 3 and has an intersection angle with respect to the tread center line a-a. , a gently sloped portion 5 larger than the similar intersection angle of the bent portion 3 is provided, and this gently sloped portion is formed at an angle θ2 in the range of 30 to 70′ with respect to the extension line of the bent portion 3, 45° in the figure. Tilt it in the direction of the tread width.

Also preferably, in each side region of the tread surface l, extending approximately parallel to the gently inclined portion 5 of the transverse groove 2,
Additional lateral grooves 6 are provided that open at each of the bent portion 3 of the lateral groove 2 and the ground contact end.

Even more preferably, the central area of the tread surface portion 1 is formed with a narrow groove such that the groove walls contact each other when the tire rolls under load, and the narrow groove is bent in the same direction as the bent portion 3 of the transverse groove 2. A groove bent portion 7 is provided, the bending intersection angle of which is made much larger than the bending intersection angle of the bending portion 3 of the transverse groove 2, and the bending center of the narrow groove bent portion 7 is set to be The tire is located on the same line segment as the circumferential line segment connecting the bending centers of the bending portion, and more preferably in at least one side area, both side areas in the figure, of the tread surface portion 1. A narrow groove inclined portion 8 consisting of narrow grooves such that the groove walls contact each other during load rolling is provided, and the intersection angle of this narrow groove inclined portion with respect to the tread center line a-a is set as the gentle slope of the transverse groove 2. be smaller than that intersection angle of part 5.

Incidentally, in each of such narrow grooves, the narrow groove bent portion 7 is formed substantially parallel to the gently inclined portion 5 of the transverse groove 2, and the narrow groove inclined portion 8 is formed parallel to the folded portion of the transverse groove 2. Preferably, it is formed substantially parallel to the curved portion 3.

(Function) In such a pneumatic radial tire, each transverse groove 2 is provided with a bent portion 3 that is approximately V-shaped when viewed from the front of the tire in the central area of the tread surface l, thereby improving hydrostatic resistance. It is possible to ensure sufficient planing performance and to effectively prevent pitch noise and high frequency noise from occurring.

Here, the bending intersection angle θ of this bending portion 3 is set to 25 to 6.
By setting the value to 0°, preferably within the range of 30 to 45°, when the intersection angle θ is less than 25°, significant uneven wear that occurs on the acute ridge defined by the bent portion 3 can be prevented. In addition, when the intersection angle θ is set to a value exceeding 60°, the pitch noise generated due to collision with the road surface at the corner of the ridge defined by the bending portion 3 can be greatly reduced. In addition to being able to reduce the amount of waste water, it is also possible to sufficiently prevent a decrease in drainage performance.

°And, by setting the formation area of the V-shaped bent portion 3 to a range of 30 to 80% of the tread road surface width, and more preferably, not forming any other groove in that area, the dry steering performance is improved. It ensures improved wet drainage performance and sufficiently prevents pattern noise, especially pitch noise.

In other words, if the formation area is less than 30%, it will not be possible to improve wet drainage and reduce pitch noise, which are the original functions of the V-shaped bend, and if it exceeds 80%, the Due to the small intersecting angle with respect to the center line of the tread surface, the stiffness of the ridges in the side areas of the tread surface portion 1 is insufficient, resulting in poor dry handling.

In addition, if only the bent part 3 is formed within the 30 to 80% area, it is possible to prevent the turbulence of the drainage water flow caused by other grooves intersecting there and to achieve extremely smooth drainage. In addition to completely eliminating the possibility of pitch noise occurring due to other grooves.

Furthermore, the bending center 4 of the bending portion 3 is set to the tread center line a-a.
By locating the bent portion 3 within a range of 25% of the tread surface width, the bent portion 3 can function particularly effectively in improving wet drainage performance and reducing pitch noise. This is because the above range has the greatest effect on wet drainage performance and pitch noise.

Incidentally, in each side region of the tread surface portion 1, the transverse groove 2 is provided with a gently sloped portion 5 that is continuous with the bent portion 3, and the gently sloped portion 5 is formed with respect to the extension line of the bent portion 3. By tilting the tread in the width direction in the range of 30 to 70 degrees, it is possible to increase the rigidity of the ridges in the side areas of the tread and improve dry steering performance. It is possible to quickly drain away water to the grounded end side.

Here, if the above angle is less than 30°, the lateral rigidity of the crest is insufficient and sufficient dry steering performance cannot be secured, and if the angle exceeds 70°, the gently sloped portion 5 The direction of extension is opposite to the direction of rotation of the tire, resulting in a significant decrease in drainage performance.

In addition, in each side area of the tread surface portion 1, a groove extending substantially parallel to the gently inclined portion 5 of the transverse groove 2 is opened at each of the bent portion 3 and the ground contact end of the transverse groove 2. When additional lateral grooves 6 are further provided, the rigidity of the ridges defined in the side areas can be made almost equal to the rigidity of the ridges defined in the central area, and the wet drainage performance is further improved. It can be improved.

In addition to the above, by forming in the central area of the tread surface part I a narrow groove bent part 7' having a bending intersection angle θ greater than the bending intersection angle θ of the bending part 3 of the transverse groove 2, When the ridges divided by the shaped bent portions 3 are subdivided in the circumferential direction by the narrow groove bent portions 7, the ground contact properties of those ridges can be improved. When the extending direction of the bent portion 7 is made substantially parallel to that of the gently inclined portion 5, the difference in rigidity between the subdivided ridges can be made sufficiently small.

Furthermore, in at least one side region of the tread surface portion 1, a narrow groove inclined portion 8 is provided whose intersection angle with respect to the center line a-a of the tread surface portion is smaller than that of the gently inclined portion 5, thereby providing extremely high lateral rigidity. When the high side area ridges are subdivided, the ground contact properties of the ridges can be improved. This is particularly effective when the difference in rigidity between the ridges is made sufficiently small.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a front view illustrating a tread pattern of a tire according to the present invention. In addition to the above, this shows a tire size of 205/60 R15, a tread surface portion 1 having a width of 160 mm, and grooves. 30% negative rate
, the groove width of the 7-shaped bent part 3 is set to 6
．． 5-1 The groove width of the gently sloped portion 5 and the groove width of the additional lateral groove 6 are both 7.0 mm, and the groove width of the narrow groove bent portion 7 extending parallel to the gently sloped portion 5 and the bent portion The groove width of each narrow groove inclined portion 8 extending parallel to 3 is 0.7 m.
m, and further, by setting the length l in the tread width direction of the region where the bent portion 3 is formed to 85 mm, that region is 53% of the tread surface width.

FIG. 2 is a front view showing another tread pattern;
The second pattern is basically the same as that shown in FIG. 1, but by setting the length l in the tread width direction of the V-shaped bent portion 3 to 110 mm, the formation area is is set to 69% of the tread surface width, and the groove width W at the bending center 4 of the bending portion 3 is set to 3.0 mm to further reduce pitch noise. By reducing the groove width to 5.5 mm, it is possible to prevent a decrease in the rigidity of the ridge section defined by the narrowed side area as a result of widening the formation area of the V-shaped bent part 3, and at the same time , the narrow groove inclined portion 8 is omitted from the narrow side region to more effectively prevent a decrease in the stiffness of the ridge.

The tread pattern shown in FIG. 3 is basically the same as the tread pattern shown in FIG. With respect to the surface center line a-a, the tire in the mounted position is offset by a distance of 13 mm toward the outside of the vehicle, and the narrow groove inclined portion 8 is omitted from the side area on the offset side, and the V-shaped fold is made. This is different from that shown in FIG. 1 in that the length l in the tread width direction of the region where the curved portion 3 is formed is set to 95 mm, thereby making the region 59% of the tread surface width.

[Comparative example]

The following is a comparison between the invented tire and a conventional tire that has particularly excellent wet drainage performance and anti-hydroplaning performance.
Comparative tests regarding pattern noise, anti-hytroprenenic performance, and dry steering performance will be explained.

◎Test Tire Both the invention tire and the conventional tire were the same in size, shape, and material, and the invention tire I had the tread pattern shown in Figure 1, the invention tire ■ had the tread pattern shown in Figure 2, and It is assumed that the invention tire (3) has the tread pattern shown in FIG. 3, and the conventional tire has the tread pattern shown in FIG. 4.

◎Test method The actual vehicle was run under the normal internal pressure and normal load based on JIS standards. Regarding pattern noise, the test was conducted on various road surfaces with different surface roughness at 100 km/h, 801 an/h, 6
By running at 0km/h and 401an/h and comprehensively evaluating pitch noise and high-frequency noise, the hydroplaning resistance performance is measured by measuring the speed at which hydroplaning occurs when driving on a road surface with a water depth of 5 mm. The dry handling performance and dry handling performance were tested by evaluating the driving feel on a dry circuit road surface.

◎Test results The results of each of these tests are shown in the table below with indices.

Note that the larger the index value, the better the result.

Table As is clear from this table, according to the invented tire, pattern noise can be greatly reduced and cabin comfort can be sufficiently improved, especially by removing circumferentially continuous grooves from the tread surface. can.

(Effects of the Invention) Thus, according to the present invention, it is possible to significantly reduce pattern noise while sufficiently maintaining dry steering performance, wet drainage performance, and hydroplaning resistance performance.

[Brief explanation of the drawing]

1 to 3 each show a tread pattern showing an embodiment of the present invention, and FIG. 4 shows a tread pattern showing a conventional example. 1... Tread surface portion 2... Transverse groove 3... Bent part 4... Center of bend 5... Gentle slope part 6... Additional lateral groove 7... Narrow groove bent part
8... Thin groove inclined portion a-a... Tread center line Figure 1! Figure 3 Figure 2 Figure 4

Claims (1)

[Scope of Claims] 1. A tire in which a plurality of transverse grooves extending in the tread width direction and having both ends open at the ground contact end are provided at intervals in the tire circumferential direction on the tread surface, comprising: In the central area of the tread surface, each of the transverse grooves is provided with a bent portion that is approximately V-shaped when viewed from the front when the tire is mounted on a vehicle, and the bending intersection angle of this bent portion is 25 to 60.
The forming area of the bent portion should be in the range of 30 to 80% of the tread surface width, and the bending center of the bent portion should be within 25° of the tread surface width from the tread center line.
%, and in each side region of the tread surface, each of the transverse grooves is provided with a gently sloped portion whose intersecting angle with respect to the tread center line is larger than that of the folded portion, This pneumatic radial tire has this gently sloped part inclined in the tread width direction at an angle of 30 to 70 degrees with respect to the extension line of the bent part. 2. An additional lateral groove is provided in each side area of the tread surface portion, extending substantially parallel to the gently sloped portion of the lateral groove and opening at each of the bent portion and the ground contact end of the lateral groove. The pneumatic radial tire according to claim 1. 3. A narrow groove bent portion is provided in the central area of the tread surface portion, consisting of narrow grooves such that the groove walls contact each other when the tire rolls under load, and bent in the same direction as the bent portion of the transverse groove; The bending intersection angle thereof is made larger than the bending intersection angle of the bending part of the transverse groove, and the bending center of the thin groove bending part is made the same as the circumferential line segment connecting the bending center of the transverse groove bending part. The pneumatic radial tire according to claim 1 or 2, wherein the pneumatic radial tire is located on a line segment. 4. In at least one side area of the tread surface,
A narrow groove inclined portion consisting of narrow grooves such that the groove walls contact each other during load rolling of the tire is provided, and the intersection angle of this narrow groove inclined portion with the tread center line is the intersection angle of the gently inclined portion of the transverse groove. The pneumatic radial tire according to claim 3, which is made smaller. 5. The narrow groove bent portion is formed substantially parallel to the gently inclined portion of the transverse groove, and the narrow groove inclined portion is formed substantially parallel to the bent portion of the transverse groove. 4. The pneumatic radial tire described in 4.