JPH0899508A - Pneumatic tire - Google Patents

Abstract

PURPOSE: To prevent side cut so as to provide superior riding comfortableness and high steering stability by radially arranging projection parts in such a state as abutting on adjoining walls, when an outer surface between a tread end and a tire maximum width part is subjected to distortion of a prescribed shape. CONSTITUTION: A side protector 21 comprising ring ribs 22A-22D which extend in the circumferential direction is formed on the outer surface between the grounding end 15A of a tread part and a tire maximum width position Wmax of a side wall part. This side protector 21 is divided into the ring ribs 2A-22D by grooved parts 24 and the angle δ of side walls which are opposed each other is set to 0-10 deg.. The side wall part is subjected to such distortion as enlarging its curvature radius in the case of cornering, however, the groove part 24 is closed and the ring ribs 22A-22D abut one another so that rigidity of the side protector 21 is held high. Therefore, side cut can be prevented so as to secure comfortable riding quality and improve steering stability.

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 pneumatic tire capable of improving steering stability while preventing side cuts.

[0002]

2. Description of the Related Art For example, in a pneumatic tire mounted on a rally vehicle traveling on an uneven terrain, a side wall is provided with a side protector because an obstacle such as rock hits the side wall.

Pneumatic tires provided with side protectors are disclosed in JP-A-61-81207 and JP-A-3-8.
There are pneumatic tires disclosed in No. 2611 and JP-A No. 5-139122.

The pneumatic tire disclosed in Japanese Patent Laid-Open No. 61-81207 solves the disadvantage of conventional pneumatic tires that the impact force against the protrusions increases when the rubber gauge of the sidewall is made thicker. By forming more than one circumferential groove to facilitate bending of the tire, the projection impact force is reduced and the running characteristics are improved.

The pneumatic tire of Japanese Patent Laid-Open No. 3-82611 has the highest height on the outer surface of the side protector at the center of the tire radius in the forming region, and the height gradually decreases toward both ends in the tire radial direction. By providing a plurality of annular ribs, an external force due to rock contacting obliquely from above and below is borne by the plurality of ribs to make cracks less likely to occur.

Further, in the pneumatic tire of JP-A-5-139122, the annular rib at the outermost radial position has a strip plate shape,
The groove bottoms of the annular grooves adjacent to each other at the radial inner position of the rib are oriented radially outwardly at an angle with respect to the tire equatorial plane. This prevents the groove from opening and improves the cut resistance.

[0007]

By the way, among the performances required for pneumatic tires to be used for rally running, cut resistance is important, but high steering stability is also important. However, in conventional pneumatic tires, only side protectors are provided for the purpose of preventing side cuts, etc., and none of them has been aimed at improving steering stability.

In view of the above facts, an object of the present invention is to provide a pneumatic tire capable of obtaining higher steering stability while preventing side cuts and ensuring a good riding comfort.

[0009]

SUMMARY OF THE INVENTION The present invention is a pneumatic tire having a cylindrical tread portion and a pair of sidewall portions extending radially inward from both ends thereof, the tread portion end and the sidewall portion. On the outer surface between the tire maximum width portion, a plurality of protrusions extending along the circumferential direction are arranged adjacent to each other in the radial direction, and the wall of one protrusion and the wall of the other protrusion adjacent to The angle to make is 0 in the tire meridian section
The angle is not less than 10 ° and is less than 10 °, and when the side wall portion is distorted in a direction to expand its radius of curvature, the wall surface of one of the protruding portions abuts the wall surface of the other protruding portion adjacent thereto. .

[0010]

According to the pneumatic tire of the present invention, the sidewall can be protected from rocks and the like by the side protector.

In order to improve the riding comfort, it is effective to lower the vertical rigidity of the tire, and to improve the steering stability, it is effective to increase the lateral rigidity of the tire. The portion from the maximum width of the tire side portion to the ground contact surface is deformed in the vertical direction of the tire (for example, when the projection is overridden), and the distortion such that the radius of curvature becomes small occurs.
When the tire is deformed in the left-right direction (for example, when a lateral force is input by a predetermined steering operation or the like), distortion such that the radius of curvature becomes large occurs.

[0012] In the pneumatic tire of the present invention, the deformation in the vertical direction of the tire causes the grooves to open, so that the rigidity does not increase. Therefore, a good ride comfort is ensured.

On the other hand, when the tire receives a lateral force due to steering operation or the like, the portion from the vicinity of the maximum width of the tire side portion to the ground contact surface is distorted so that the radius of curvature becomes large, the groove portion between the protruding portions is closed, and the protruding portion is closed. The rigidity of the side protector can be kept high by bringing them into contact with each other. As a result, the rigidity of the tire in the left-right direction is increased and deformation (expansion of the radius of curvature of the tire side portion) is suppressed, so steering stability can be improved.

If the angle between the wall surface of one of the protruding portions forming the groove and the wall surface of the other protruding portion is 10 ° or more,
The wall surface of the one protruding portion and the wall surface of the other protruding portion may not come into contact with each other, and the steering stability cannot be improved.

[0015]

EXAMPLE An example of the pneumatic tire of the present invention will be described below with reference to FIG.

As shown in FIG. 1, a pneumatic radial tire (in this embodiment, tire size 195 / 65R1
5) Both ends in the tire width direction of the carcass 16 of 10 are bead cores 1 arranged in a ring shape on an inner peripheral portion in the tire radial direction.
4 are folded back from the inner side in the tire width direction toward the outer side in the tire width direction.
It is 6A. The material of the cord of the carcass 16 of this embodiment is polyester.

A top tread 15 made of thick rubber is arranged at the outermost portion in the radial direction of the pneumatic radial tire 10, and the carcass 16 has a top tread 15 side (upper side in FIG. 1). Steel belt layer 1
8 and 20 are arranged adjacent to each other.

On both sides of the carcass 16 in the width direction, side rubbers having a substantially constant thickness are arranged between the bead portion 19 and the top tread 15 to form sidewall portions 10A.

On both sides of the pneumatic radial tire 10, the tire maximum width position W _{max of the} sidewall portion 10A is provided.
The side protector 21 is provided between the bottom tread 15 and the grounding end 15A of the top tread 15.

The side protector 21 of this embodiment is formed of four annular ribs 22 of annular ribs 22A, 22B, 22C and 22D.

These annular ribs 22A, 22B, 22
C and 22D project to the outside of the tire from the outer contour line L of the sidewall portion 10A. That is, from the pneumatic tire 10 to the annular ribs 22A, 22B, 22C, 22D
When removed, the tire becomes a general pneumatic tire without the side protector 21.

The annular rib 22A adjacent to the grounding end 15A has a substantially triangular cross section, and the other annular ribs 22B,
22C and 22D have a substantially rectangular cross section. These annular ribs 22A, 22B, 22C, 22D are formed such that their base portions are in contact with each other.

Grooves 24 provided between the annular ribs 22
Has a narrow V-shape when viewed from the tire meridian section, and the angle θ formed between the side walls of the annular rib 22 forming the groove 24 is 2 °. In addition, the annular ribs 22A, 22B, 2
2C and 22D have a height H of 4.5 mm and annular ribs 22B and 2
2C and 22D have a base width w of 8 mm. In this embodiment, the rubber material forming the annular ribs 22A, 22B, 22C, 22D is the same as the rubber material of the side rubber forming the sidewall portion 10A, and the hardness is 50 degrees in Shore A hardness. Is.

Next, the operation of this embodiment will be described.
Since the pneumatic tire 10 of the present invention is provided with the side protector 21, it is possible to protect the sidewall portion 10A from contact with rocks or the like when traveling on rough terrain.

When the pneumatic tire 10 is deformed in the vertical direction, the sidewall portion 10A is distorted in the direction in which its radius of curvature becomes smaller. In this case, since the groove 24 is in the opening direction, the vertical rigidity does not increase, and good riding comfort can be ensured even when traveling on an uneven road surface.

On the other hand, when cornering is performed by a steering operation, a lateral force acts on the pneumatic tire 10 to deform it in the left-right direction. When the pneumatic tire 10 is deformed in the left-right direction, the sidewall portion 10A is deformed such that the radius of curvature becomes large particularly in the portion from the tire maximum width position W _{max of the} sidewall portion 10A to the ground contact end 15A of the top tread 15. receive. When the strain in the direction in which the radius of curvature of the sidewall portion 10A increases becomes greater than or equal to a predetermined value, the groove portion 24
Is closed and the annular ribs 22 come into contact with each other, whereby the rigidity of the side protector 21 can be kept high. As a result, the rigidity of the tire in the left-right direction is increased and the deformation is suppressed, so that the steering stability is improved as compared with the conventional pneumatic tire.

A conventional pneumatic tire (Japanese Unexamined Patent Publication No. 61-61160)
-81207, JP-A-3-82611, and JP-A-5-
No. 139122), the opening of the groove is large and the groove does not close at the time of cornering. Therefore, unlike the pneumatic tire 10 of the present embodiment, it is not possible to improve the steering stability when a lateral force is applied. (Test Example) A pneumatic tire to which the present invention is applied (a pneumatic tire of an example) and a conventional tire (a tire obtained by removing the side protector from the pneumatic tire of the example) are prepared, and a tire spring characteristic test and a tire cornering are prepared. A power test and a tire enveloping test were conducted with a testing machine.
In the tire enveloping test, a protrusion having a predetermined size was attached to the drum and the forces acting on the tire shaft were compared.

Test conditions Tire size: 195 / 65R15 Load: 400 kgf Internal pressure: 2.0 kgf / cm ²

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

From the results shown in the above table, the pneumatic tire 10 of this embodiment has almost the same vertical spring constant as compared with the conventional tire (the difference in the value is the difference in the degree of product variation). It can be said that the ride comfort is equivalent.

Further, in the pneumatic tire 10 of this embodiment, as compared with the conventional tire, the spring constant in the left-right direction and the tire cornering power are improved, and it is clear that the steering stability is improved.

Further, from the results shown in Table 3, the pneumatic tire 10 of the present embodiment has the same tire enveloping power as compared with the conventional tire, and the side protector absorbs the impact (riding comfort) when overcoming the protrusion. It turns out that it does not inhibit.

In the above embodiment, the annular ribs 22A,
The hardness of the rubber material forming 22B, 22C and 22D is 50 degrees in Shore A hardness, but the annular ribs 22A, 22B,
The hardness of the rubber material forming 22C and 22D is not limited to this. Annular ribs 22A, 22B, 22C,
The hardness of the rubber material constituting 22D is 45 in Shore A hardness.
It is preferably within the range of 80 to 80 degrees. In addition, the annular rib 22
The rubber material forming A, 22B, 22C, 22D may be a rubber material different from the side rubber forming the sidewall portion 10A.

In the above embodiment, the side protector 21 is composed of four annular ribs 22, but the side protector 21 may be composed of at least two annular ribs 22. Of course, it may be configured by the above annular rib 22.

Further, in the above embodiment, the side protector 21 is composed of the annular rib 22. However, the annular rib 22 may be divided into a plurality of pieces in the tire circumferential direction (for example, blocks are arranged in a row).

In the above embodiment, the groove 24 has a V-shape having an angle of 2 ° in the direction of opening toward the outside of the tire. However, the side walls of the annular rib 22 facing each other are parallel, that is, the angle θ is 0. May be 0 ° (for example, the groove 24 shown in FIG. 7 or a sipe having substantially no groove width), and may be in the range of 0 ° or more and less than 10 °.

In the above embodiment, the groove portion 24 has a V-shape having an angle of 2 ° in the direction of opening toward the outside of the tire, and the groove width at the groove bottom portion is zero. If the side walls of the annular ribs 22 come into contact with each other during expansion, the groove bottom portion may have a slight groove width.

Further, the height h of the annular rib 22 is 2 mm to 1
About 0 mm is preferable. Here, if the height h of the annular rib 22 is less than 2 mm, the ability to suppress the deformation of the sidewall portion 10A in the direction of increasing the radius of curvature is reduced, and the steering stability is the same as that of the conventional pneumatic tire.

The width w of the annular rib 22 is 5 mm to 20 mm.
mm is preferable. Here, the width w of the annular rib 22 is 20.
If it exceeds mm, the rigidity becomes high and the sidewall part 10A
Since the deformation in the direction in which the radius of curvature becomes smaller is suppressed and the vertical spring constant of the tire is increased, the riding comfort may be reduced. On the other hand, if the width w of the annular rib 22 is less than 5 mm, the rigidity of the annular rib 22 itself decreases, which is not preferable.

Further, the shape of the side wall of the annular rib 22 forming the groove portion 24 is linear in the above-mentioned embodiment, but it may be in contact with each other when the radius of curvature of the side wall 10A expands. As shown, the vicinity of the opening may have a curved shape, as shown in FIG. 4, the entire shape may have a curved shape, and as shown in FIG. You may be present.

As shown in FIGS. 6 and 7, the groove 2
The bottom of No. 4 may be shaped like a flask, whereby strain concentration at the bottom can be alleviated.

The groove 24 is also seen in the meridian section of the tire.
The width center may be perpendicular to the outer contour line L of the pneumatic tire 10 or may be inclined to some extent.

Further, the annular rib 22 may have different shapes, dimensions and the like. Further, the internal structure of the pneumatic tire 10 is not limited to the above-mentioned embodiment, and a well-known structure can be applied, and a bias structure or the like other than the radial structure may be used.

[0046]

As described above, since the pneumatic tire of the present invention has the above-mentioned constitution, prevention of side cut,
It has an excellent effect that it is possible to obtain higher driving stability than the conventional one while ensuring a good riding comfort.

[Brief description of drawings]

FIG. 1 is a sectional view of an upper left half taken along a tire width direction showing a pneumatic radial tire according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a side protector of the pneumatic tire shown in FIG.

FIG. 3 is still another embodiment of the side protector.

FIG. 4 is still another embodiment of the side protector.

FIG. 5 is still another embodiment of the side protector.

FIG. 6 is still another embodiment of the side protector.

FIG. 7 is still another embodiment of the side protector.

[Explanation of symbols]

10 Pneumatic Radial Tire 15 Top Tread (Tread Part) 10A Sidewall Part 22A Annular Rib (Projection) 22B Annular Rib (Projection) 22C Annular Rib (Projection) 22D Annular Rib (Projection) 24 Groove _Wmax Tire Max Large section

Claims (1)

[Claims] 1. A pneumatic tire having a cylindrical tread portion and a pair of sidewall portions extending radially inward from both end portions thereof, wherein the tread portion end and the tire maximum width portion of the sidewall portion. On the outer surface of the, a plurality of protrusions extending in the circumferential direction are arranged adjacent to each other in the radial direction, and the angle formed by the wall surface of one protrusion and the wall surface of the other protrusion adjacent to each other is measured in the tire meridian section. The angle is 0 ° or more and less than 10 °, and when the sidewall portion is strained in a direction of expanding its radius of curvature, the wall surface of one of the protruding portions abuts the wall surface of the other protruding portion adjacent thereto. Pneumatic tires.