JPH0764166B2 - Pneumatic tire - Google Patents

Description

The present invention relates to a pneumatic tire having improved traction performance on a snowy road surface.

[Conventional technology]

Conventionally, in snow tires used for traveling on snowy roads, blocks of various shapes are arranged in the tread portion, siping, etc., and the amount of bite into the snow surface of the block and the block edge, the snow surface by the siping edge Shaving,
By increasing the scratching effect, traction performance such as braking performance, starting performance, and climbing performance is improved.

[Problems to be Solved by the Invention]

However, all of these conventional devices are means for improving the tread pattern, and have not yet achieved sufficiently satisfactory effects, and further improvements have been desired in recent years.

The present invention has been made paying attention to the fact that the tire bulletless portion comes into contact with the rut wall surface formed on the snow-covered road, especially when running on the snow-covered road, and forms the engaging portion on the shoulder block. Based on this, it is an object of the present invention to provide a pneumatic tire that contributes a new traction action to the buttress portion and can greatly improve the traction performance of the tire as a whole.

[Means for Solving the Problems]

The pneumatic tire of the present invention to achieve the above object,
The tread portion is provided with a mechanism for opening a buttress surface continuous with the tread edge so as to form a shoulder block arranged circumferentially along the tread edge between the lateral grooves, and a tire axial direction of the tread edge. A plurality of locking portions having a narrow groove portion opening at the buttress surface with the inner shoulder block upper surface as a starting point, and a raised portion having an upper surface continuous with the groove bottom surface of the groove portion and protruding from the buttress surface, It is formed on the shoulder block.

The starting point of the narrow groove portion is the distance L from the tire equator.
Is preferably 0.460 times or more and 0.4975 times or less of the tread width WT, which is the length in the tire axial direction between the tread edges, and the ridge is the lateral groove depth radially inward from the upper surface of the shoulder block. It is preferable to have protruding portions protruding from the buttress surface at radial positions spaced apart by 15%.

[Action]

In the pneumatic tire configured as described above, on the rut road surface, the raised portion provided at the locking portion meshes with the rut wall surface, and the shaving effect and the scratching effect cause the traction action. Also, the narrow groove part of the locking part is a smooth road surface,
It is possible to grip the road surface on both rut surfaces and cooperate with the raised portions to further improve traction performance.

By controlling the radial position of the projecting portion, that is, the projecting region in the radial direction of the raised portion and the starting point position of the narrow groove portion, it is possible to suppress uneven wear and effectively improve the traction performance from the initial stage to the final stage of wear.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 illustrates a tread pattern of a pneumatic tire 1 of the present invention. The pneumatic tire 1 has four main grooves G1, G1, G2, which extend in a tire circumferential direction on a tread portion 2 in this example. G2
By providing recesses (generally referred to as main groove G) and a lateral groove K ... One end of which is open at the buttress surface 3 connected to the tread edge T and which extends across the main groove G, the tread portion 2 is provided. A center block row UC composed of center blocks BC, which are separated from each other on the tire equator, and a tread edge T
A shoulder block row US made up of shoulder blocks BS ... And a middle block row UM in which intermediate blocks BM ... are juxtaposed between a center block row UC and a shoulder block row US are formed.

Each of the block rows UC, UM, and US is in the tire circumferential direction.
Comprising 25 to 60 blocks BC, BM, BS, said blocks BC,
The ratio SA / S of the total area SA of the BM and BS upper surfaces to the total surface area S of the tread portion 2 is set to 0.45 to 0.75, more preferably 0.5 to 0.7. When the ratio SA / S is more than 0.75, the wear resistance is excellent, but the meshing force with snow and ice is reduced,
When the performance on snow and ice is reduced and it is less than 0.45,
The ground contact area is too small and wear resistance is reduced.

Further, the upper and side edges of each block BC, BM, BS are respectively formed by edges, and rectangular concave and convex portions are provided on the front and rear end surfaces S1 facing the lateral groove K and the end surface S2 facing the main groove G. As a result, the ability to mesh with snow and ice and the scratching effect are enhanced.

Further, in the shoulder block BS, a plurality of locking portions 7, ... In this example, are formed to project from the buttress surface 3.

The locking portion 7 extends outward from the shoulder block BS upper surface located at a distance l1 inward in the tire axial direction from the tread edge T as a starting point 9 and the other end has a narrow groove portion 10 opening at the buttress surface 3. The narrow groove portion 10 has a top surface 11A continuous with the bottom surface 10A, and a bulge portion 11 protruding from the buttress surface 3 by a distance l2 in the tire axial direction. The ridge portion 11 is an end surface substantially parallel to the buttress surface 3. 11B is aligned with buttress surface 3.

Further, the bottom surface 10A of the narrow groove portion 10 and the top surface 11A of the raised portion 11 are
In this example, the inclination angle θ forms the same slope with about 40 degrees, and both the upper edge 10a of the narrow groove portion 10 and the upper edge 11a of the raised portion 11 are formed by edges.

Therefore, the locking portion 7 formed in this manner enhances the traction performance by the shaving effect of the snow caught in the narrow groove portion 10 by the upper edge 10a, while the ridge portion 11 protruding from the buttress surface 3 moves in the traveling direction. A new traction action can be generated by the scratching and scraping effect on the rut wall surface formed on the compressed snow road surface by the facing side surface 11c.

In addition, the raised portion 11 has a buttress at the inner side of the radial position X which is a tire wear estimated line which is separated from the upper surface of the shoulder block BS by 15% of the groove depth H of the lateral groove K inward in the radial direction. It is preferable to have a projecting portion 12 projecting from the surface 3 so that the traction effect can be produced from the early stage to the final stage of tire wear. Moreover, in order to exert such an effect effectively,
The distance L from the tire equator CO to the starting point 9 is 0.46 of the tread width WT, which is the axial length between the tread edges T and T.
The distance l1 from the tread edge T is 1.5 mm or more and 8 mm or more.
The following is desirable.

Also, the distance l2 from the tread edge T to the upper edge 11a of the raised portion 11
Is 0.01 times the tread width WT or more.

This is derived from various actual vehicle tests conducted by the present inventor, and an example of the test results is shown in FIGS.

The test was carried out using a prototype tire having a tread pattern shown in FIG. 1 and a tire size of 10.00R20 on a vehicle (2-
D-4) is an actual vehicle running test carried out based on the conditions shown in Table 1, and FIG. 5 shows the distance L on a flat compressed snow road surface. The relationship between the braking performance and the braking performance, and the relationship between the distance l2 and the braking performance on the rugged snow-covered road surface in FIG. 6, and the heel and toe wear amount on both sides of the narrow groove portion 10 in FIG. The relationship with each (after running 30,000 km) is shown.

As shown in FIGS. 5 and 7, when the distance L exceeds 0.4975 WT, the traction performance is deteriorated and the braking performance is deteriorated.
If it is less than 0.46 WT, the heel and toe wear will be large and it will be unsuitable for actual use.

If the distance l2 is less than 0.01 WT, the braking performance deteriorates as shown in FIG. 8 to 9 show another embodiment of the engaging portion 7. In FIG. 8, the locking portion 7 has a raised portion 11 wider than the narrow groove portion 10. Further, in FIG. 9, the locking portion 7
Is a top surface 1 that intersects the bottom surface 10A at an angle outside the narrow groove portion 10 having a bottom surface 10A parallel to the top surface of the shoulder block BS.
A raised portion 11 having 1A is provided.

〔The invention's effect〕

As described above, the pneumatic tire of the present invention is provided with a locking portion having a narrow groove portion opening at the buttress surface and a raised portion protruding from the buttress surface in the shoulder block, and therefore when traveling on a snow-compacted road surface. By engaging the locking portion with the rut wall surface formed on the road surface, a new traction effect can be generated, and snow running performance can be greatly improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the tread pattern of the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is an enlarged perspective view of a shoulder block, and FIG. 5 is a diagram showing the relationship between the distance L and the braking performance, and FIG. 6 is a diagram showing the relationship between the distance 12 and the braking performance.
FIG. 7 is a diagram showing the relationship between the distance L and heel and toe wear, and FIGS. 8 to 9 are perspective views showing another embodiment of the locking portion. 2 ... Tread part, 3 ... Buttress surface, 7 ... Locking part, 9 ... Starting point, 10 ... Small groove part, 10A ... Bottom part, 11 ... Raised part, 11A ... Top part, 12 ... Protruding part.

Claims (2)

[Claims] 1. A tread portion is provided with a mechanism for opening a buttress surface continuous with a tread edge so as to form shoulder blocks arranged in the circumferential direction along the tread edge between the lateral grooves, and the tread is provided. A plurality of narrow width groove portions that open at the buttress surface starting from the shoulder block upper surface inward of the tire in the tire axial direction, and a raised portion that has an upper surface continuous with the groove bottom surface of the groove portion and that protrudes from the buttress surface A pneumatic tire in which a locking portion is formed on the shoulder block. 2. The starting point of the narrow groove portion is such that the distance L from the tire equator is not less than 0.460 times and not more than 0.4975 times the tread width WT which is the length in the tire axial direction between the tread edges, and is raised. The pneumatic tire according to claim 1, wherein the portion has a protruding portion that protrudes from the buttress surface at a radial position that is separated from the upper surface of the shoulder block in the radial direction by a distance of 15% of the lateral groove depth.