JPH05139122A - Pneumatic tire having improved cut resistance - Google Patents

Abstract

PURPOSE:To ensure the cut resistance characteristics while ensuring the steering stability and mitigating the travel vibration, by forming annular ribs and annular boundary portions into beaklike configurations tapered in the radially inward direction. CONSTITUTION:Annular ribs 7 located near a tread portion 5 and at the radially outermost position are each in the form of a band-like strip. Each of annular grooves 6 adjacent to each other at each inner radial position of each annular rib 7 has a groove width smaller than the band width of the annular rib 7, and each groove bottom 8 is directed radially outward at an angle with respect to an equator line O-O of the tire, and each groove opening 9 is formed being directed radially inward. As a result, even when an oblique force F acts on a side wall portion 3 during a car travel resulting from earth contact on a road surface G and rotation of a tread portion 5 of the pneumatic tire 1 mounted to a motor sport vehicle, the tire is guarded by the band shaped annular groove 7. On the other hand, when rock pieces, wood pieces, etc., are caught in the annular grooves 6, since the groove opening 9 of the groove 6 is directed radially inward and the beaklike boundary portion 10 is elastically deformed so as to close the groove, such pieces are prevented from being bitten.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having improved cut resistance and is used in a vehicle for motor sports such as rallies.

[0002]

2. Description of the Related Art A vehicle for motor sports such as a rally often runs on an irregular road. Therefore, in a pneumatic tire mounted on the vehicle, the side wall of the pneumatic tire hits rocks, stones, etc. It was easy to receive the air, and the air might escape from the cut. Therefore, JP-A-3-82611
As disclosed in Japanese Laid-Open Patent Publication No. 61-81207, the outer surface area of the side wall portion is formed with alternating annular grooves and annular ribs having a radius centered on the tire axis and is cut resistant. Technology is available.

[0003]

In a conventional pneumatic tire having improved cut resistance, annular grooves and annular ribs are arranged radially in the tire cross section or along the tire axial direction. It was However, in these conventional techniques, when a force in an oblique direction acts from the road surface, the rigidity of the annular rib is low, so that not only the guard rib function is impaired but also the annular groove opens and the tip of rock or the like is pulled to the annular groove wall. On the contrary, there was a problem of promoting side cuts.

In view of this, the present invention improves the rigidity by making the groove opening of the annular groove radially inward and forming the annular rib into a strip plate shape, thereby preventing the opening of the groove while sufficiently exhibiting the guard rib function. The purpose is to improve cut resistance.

[0005]

According to the present invention, an annular groove 6 having a radius centered on a tire axis is provided in an outer surface area of a side wall portion 3 on a tread side, and an annular rib is provided at a radially outer position of the annular groove 6.
The following technical measures are taken in order to achieve the above-mentioned object in a pneumatic tire having 7 improved cut resistance.

That is, according to the present invention, the annular rib 7 at the outermost radial position close to the tread portion 5 is in the shape of a strip plate, and the annular groove 6 adjacent at the radial inside position of the annular rib 7 has the groove width as described above. The groove bottom 8 is smaller than the band width of the rib 7 and is oriented radially outward with an angle with respect to the tire equator line OO, and the groove opening 9 is oriented radially inward. It is characterized by.

[0007]

[Function] Tread portion 5 of pneumatic tire 1 mounted on the vehicle
When the vehicle is traveling by rotating the ground contacting the road surface G, even if the diagonal force F acts on the side wall portion 3, the annular rib 7 in the shape of a band plate provides a guard function. On the other hand, rocks, trees, etc. are caught in the annular groove 6 because the groove opening 9 of the groove 6 is directed in the radial direction and the beak-shaped boundary portion 10 is elastically deformed so as to close the groove. Prevent biting.

Further, the suspension of the vehicle is secured by the annular groove 6.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in detail below with reference to the drawings. In FIG.
1, more specifically, a pneumatic radial tire mounted on a vehicle such as a rally has a toroidal cross section in which a pair of left and right bead parts 2 are continuously connected by a tread part 5 via a side wall part 3 and a shoulder part 4. Formed on each bead part 2
A bead core is embedded in the, and these bead cores are connected to each other by a radial carcass, and the tread part is
5 has a belt.

Although one side wall part 3 is shown in the figure, the tread part 5 of the pair of left and right side wall parts 3 is shown.
In the present embodiment, the first to fourth annular grooves 6 and the first to fifth annular ribs 7 have a radius centered on the tire axis in the outer surface area on the side, and the tire cross section height is 35% to 35% from the tread portion 5. They are formed alternately within the range. In the present embodiment, among the annular ribs 7, the first rib located at the outermost radial position and the second to fourth ribs located at the radially inner position thereof have a strip plate shape whose outer surface is gradually narrowed in accordance with the inner diameter. The fifth rib has a rounded shape.

On the other hand, in the present embodiment, the first groove and the second groove located at the outermost radial position of the annular groove 6 have their groove bottoms 8 radially outward with respect to the tire equator line OO. And the groove opening 9 is directed in the radial direction, whereby the boundary portion 10 of the annular groove 6 of the annular rib 7 is formed in a beak shape that is tapered in the radial direction. Further, the groove width of the first groove and the second groove is smaller than the rib width of the corresponding first rib and second rib, and the force F in the oblique direction from the road surface G is increased.
The first rib, the second rib, and the like perform a guard rib function when actuated, and the beak-shaped boundary portion 10 elastically deforms in the direction of closing the groove opening 9 to allow the stone or wood piece to bite or bite into the groove. Prevent jamming.

On the other hand, the third groove and the fourth groove are groove openings 9 whose groove depth direction is substantially parallel to the tire axis, thereby allowing elastic deformation of the side wall portion 3 in the radial inside and outside directions, Therefore, the vehicle suspension is secured. It should be noted that the groove bottom 8 of the annular groove 6 has a roundness in any groove, which relaxes the stress concentration, and
And the like, the cut resistance is improved, the groove width is at least 3 mm and the groove depth is 3 mm or more, the angles θ1 and θ2 are 10 ° or more, and θ1> θ
It is supposed to be 2.

In the second embodiment shown in FIG. 2, the rib width of the first rib of the annular rib 7 is widened, thereby increasing the guard rib action, and the third embodiment shown in FIG. In the annular rib 7, the rib width of the second rib is larger than that of the first rib. In FIG. 4, the boundary portion 10 has a triangular shape, and in FIG. 5, the boundary portion 10 has a rounded shape.

In addition, in FIGS. 1 to 3, reference numeral 11 denotes a rim.

[0015]

The present invention is as described above, and an annular groove 6 having a radius centered on the tire axis is provided in the outer surface area of the side wall portion 3 on the tread side, and an annular rib is provided at an outer radial position of the annular groove 6. In the pneumatic tire with improved cut resistance provided with 7, the annular rib 7 at the outermost radial position near the tread portion 5 is a strip plate shape, and the annular groove 6 adjacent to the annular rib 7 at the radial inside position is provided.
This groove width is smaller than the band width of the annular rib 7 and the groove bottom 8
Is directed radially outward with an angle with respect to the tire equator line OO, and the groove opening 9 is directed radially inward,
Since the boundary portion 10 between the annular rib 7 and the annular groove 6 is formed in a beak shape that is tapered in the radial direction, the annular groove 6 provides the suspension action of the side wall portion 3 to reduce steering stability and traveling vibration. At the same time, the ring-shaped rib 7 ensures the cut resistance by the guard rib action.

Further, since the groove opening 9 of the annular groove 6 is oriented in the radial direction, it is possible to suppress the biting or biting of stones, wood chips or the like from the road surface G and to enlarge the groove opening 9. Since it is small, the cut resistance is significantly improved, and since the groove is closed by the elastic deformation by the beak-shaped boundary portion 10, biting of stones, wood chips, etc. is surely prevented and a burst occurs. It is less susceptible to cuts, which is a real benefit, especially as a pneumatic tire for vehicles used in rally motorsports.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a sectional view of a second embodiment.

FIG. 3 is a sectional view of a third embodiment.

FIG. 4 is a cross-sectional view of main parts of a fourth embodiment.

FIG. 5 is a cross-sectional view of essential parts of a fifth embodiment.

[Explanation of symbols]

 1 Pneumatic tire 3 Sidewall part 5 Tread part 6 Annular groove 7 Annular rib 8 Groove bottom 9 Groove opening 10 Boundary part

Claims (1)

[Claims] 1. An annular groove (6) having a radius centered on the tire axis and an annular rib (7) located radially outside of the annular groove (6) in the outer surface area of the side wall portion (3) on the tread side. In the pneumatic tire with improved cut resistance, the annular rib (7) at the outermost radial position close to the tread portion (5) has a strip shape and is adjacent to the annular rib (7) at the radial inside position. Annular groove
(6) indicates that the groove width is smaller than the band width of the annular rib (7), the groove bottom (8) is oriented at an angle radially outward with respect to the tire equator line OO, and A pneumatic tire with improved cut resistance, characterized in that the opening (9) is formed in a radial direction.