JPH02293205A - Rotation direction-designated pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the drive performance and brake performance of a pneumatic tire such as a studless tire by forming a side end of a land part to be grounded precedingly acute, and a side end to be grounded subsequently obtuse, and providing a buttress part at a groove bottom along the precedingly grounded side end of the land part. CONSTITUTION:An edge e2 at a side end of a land part 3 on the side to be grounded precedingly at the time of rolling is formed having an acute angle theta2, and an edge e1 of a side end on the side to be grounded subsequently is formed having an obtuse angle theta1, while a buttress part (b) is provided at the groove bottom of a groove part 2 along the side end on the side to be grounded precedingly. In this constitution, falling down of the land part 3 at the time of braking can be prevented by the buttress part (b), and the braking perfor mance can be improved by concentrated loosening of a ground pressure by the obtuse angle of the edge e1 on the kicking side. Traction at the time of on-snow run can be improved by the acute angle of the stepping side edge e2. The brake and drive performance can thus be improved.

Description

[Detailed Description of the Invention] (Industrial Application Field) Tires used for driving on snowy and/or icy roads, such as studless tires, are required to have high traction and braking performance on icy and snowy surfaces. This invention aims to advantageously improve the driving performance on snow and ice, especially the driving performance on snow and the braking performance on ice, of pneumatic tires mounted on vehicles that run on snowy and icy roads. It is something.

(Prior art) In addition to forming a concavo-convex pattern by disposing grooves and land portions separated by the grooves on the entire surface of the tread, the angle of the side edge of the land portion along the tread width is changed. By this,
Attempts to improve the performance of tires on snow and ice by applying textured edges to snow-covered and icy roads are known, as seen in Japanese Patent Application Laid-open No. 6397405, for example. During braking on snow-free or icy roads, the land portions on the tread surface may collapse, resulting in functional deterioration.

(Problems to be Solved by the Invention) In order to improve the driving performance on snow, it is necessary to sink the side edge of the tread land portion that contacts the ground first during rolling into the road surface. For this reason, it is necessary to appropriately deform the land portion and increase the ground contact pressure at the side ends. On the other hand, in order to improve the braking performance of tires on icy roads, it is necessary to avoid local concentration of ground pressure on the land area separated by grooves, in other words, to make the surface uniform in ground pressure distribution and to increase the friction area as much as possible. There is a need to.

However, in the conventional technology as described above, the land portion simply stands upright from the groove bottom of the tread, which not only easily causes bending deformation during braking and driving, but also prevents local concentration of ground pressure. It was not possible. For this reason, although it is possible to improve either driving performance on snow or braking performance with this type of technology, it is difficult to improve both simultaneously or to improve braking performance, especially on icy roads with no snow. It was becoming difficult to improve the balance between work and work.

During driving, the land contact pressure at the side edges of the tread is increased by deformation of the tread land, and this edge is embedded into the road surface, improving drive performance on snowy roads, etc. When braking the vehicle, the land on the tread An object of this invention is to propose a pneumatic tire that can avoid deformation and local concentration of ground pressure, thereby increasing frictional resistance between road surfaces and maintaining excellent braking performance on icy roads. It is a purpose.

(Means for Solving the Problems) The present invention provides a pneumatic tire in which a groove portion and a land portion separated by the groove portion are arranged on the entire surface of the tread to form an uneven tread pattern, when the tire rolls. The edge on the side that touches the ground after the land section has an obtuse angle, and the edge on the side that touches the ground first has an acute angle. This is a pneumatic tire that can specify the direction of rotation.

Now, in FIG. 1, the main parts of the pneumatic tire according to the present invention are shown in a cross section perpendicular to the rotational axis of the tire.
is also the land area.

The land portion 3 is the edge e1 on the side that contacts the ground later when the tire rolls.
is at an obtuse angle, and the edge e2 on the side that touches the ground first is at an acute angle. Further, the groove portion 2 has a buttress portion b on the bottom of the groove along the side edge of the land portion 3 that contacts the ground first, which serves to prevent the land portion 3 from collapsing. It may be continuous or intermittent along the width direction.

Note that the internal structure of the tire is the same as that of a general radial tire, and is not illustrated here.

(Function) The edge e of the land portion 3 on the side that touches the ground later when the tire rolls.
In a tire with a structure as shown in Fig. 2(a), where the edge e4 is an acute angle and the edge e4 that contacts the ground first is an obtuse angle,
When suppressing tire transfer, it is advantageous to shorten the braking distance by catching the edge e3 on the side that will touch the ground later on the road surface R, but on the other hand, the ground pressure of the tire is concentrated in that area, and the vehicle Unable to get large traxigons when moving forward.

In addition, as shown in FIG. 2(b), the edge e on the side that touches the ground from the rear of the land portion 3 is obtuse, and the edge e on the side that makes contact with the ground first.
On the other hand, with a structure in which 6 is at an acute angle, large traction can be obtained, but when suppressing tire transfer, the specific situation is shown in Figure 3, where the land part 3 is deformed and the land part 3 It is unavoidable that the edge e on the side of the tread 3 that contacts the ground first is lifted and the ground contact area of the tread 1 is significantly reduced.

Although it is conceivable to adopt a structure that combines the above-mentioned structures as in the prior art mentioned above, this has not resulted in the reduction of edge components useful for braking the tire and thus has not improved braking performance.

In this invention, the buttress portion b provided at the groove bottom along the side edge of the land portion 3 that contacts the ground first prevents the land portion 3 from collapsing during braking, so the ground contact area of the tread 1 is reduced. There is no clearing. Therefore, the contact area between the road surfaces can be expanded, that is, the frictional resistance between the road surfaces can be increased, and braking performance can be advantageously improved.

Here, the reason why the edge e1 on the side that touches the ground after the land portion 3 is made obtuse and the edge e2 on the side that makes contact first is made at an acute angle is that first, on the side that touches the ground later, the edge e is made obtuse. During braking, the concentration of ground pressure at that part can be alleviated, and a suitable edge angle is θ.
, =100~135° is good.

In addition, for the side that touches the ground first, by making the edge e2 acute, high traction can be obtained when driving on snow, etc., and a more preferable angle is θ2=4
It is preferable to set it to 5-80''.

In addition, in this invention, the edge e on the side that comes into contact with the ground first during driving
In order to further improve the traction by concentrating the ground contact pressure at 1, as shown in FIG. You can also do it.

The land portion 3 illustrated in the description of the present invention is advantageously suitable for all tread patterns such as ribs, lugs, and rib-lugs depending on the characteristics of the road surface, in addition to blocks.

(Example) Size: 175/70R13 (1 for 2 passengers) The tread part has blocks configured as shown in Figure 1.
Using a vehicle equipped with 800cc front-wheel drive tires on both front and rear wheels, tests were conducted repeatedly on snowy and icy roads at a speed of 40 km/h and sudden braking to determine the traction and We investigated braking performance.

In this test, a tire of the same size and having a block as shown in FIG. 5 in which the edge on the side that will touch the ground later and the edge on the side that will touch the ground first are both at right angles was used as a reference.

The results are shown in the table below, and it was confirmed that the tire according to the present invention exhibited higher performance than the tire having blocks as shown in FIGS. 2(a) and 2(b) used as a comparison tire. .

Key points of the pneumatic tire according to this invention Figure 4 shows Partial sectional view, Figure 5 shows the reference tie. 1... tread, 3... Rikube, C I A′ eh ...edge, FIG.

2...Groove portion, b...Buttress portion, R...Road surface (Effects of the invention) Thus, according to the present invention, the driving performance on snow is improved and at the same time, the deformation of the land portion of the tread surface is reduced during braking. Since this does not cause any problems, braking performance is improved, especially on icy roads, and safe driving can be achieved.

[Brief explanation of drawings]

Figure 1 shows a cross section of the main parts of a pneumatic tire according to the present invention.
Figure 2 (a) (b) is a cross-sectional view of a conventional tire, Figure 3 is an explanatory diagram of the deformation of the land area, Figure 1 Figure 2 (a) (b)

Claims (1)

[Claims] 1. In a pneumatic tire in which a groove and a land area separated by the groove are provided on the entire surface of the tread to form an uneven tread pattern, when the tire rolls, the land area is The side edge on the side that touches the ground first is at an acute angle, and the side edge on the side that touches the ground later is at an obtuse angle, and the groove section has a buttress part at the bottom of the groove along the side edge on the side that touches the ground first. A pneumatic tire with a specified rotation direction.