JPS5853604B2 - Rally tires - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rally tire.

Generally speaking, racing tires pursue the ultimate in speed and maneuverability on paved circuits, whereas Rally tires are used in the ever-changing rough road conditions such as sand, gravel, muddy, or ice-covered roads. All-in-one adaptation is required.

On the other hand, due to the expansion of paved roads in mountainous areas in recent years, opportunities to drive on paved roads are increasing even in rally competitions.

Therefore, the performance required of today's rally tires is not only high running performance on rough roads, but also high running performance on paved roads.

Conventional tires of this kind are designed primarily for rough roads, so they have excellent grip on muddy and gravelly surfaces, but when driving on paved roads at the limits of speed and maneuverability, they suffer from unsteady handling and wet tires. There are various problems with skids, and in terms of durability, phenomena such as local wear of the tread blocks occur, and the performance level is lower than that of general tires for use on paved roads.

In this regard, it goes without saying that tires for paved roads are completely useless when attempting to drive on rough roads.

In view of these points, the present invention provides a tire that is suitable for today's rally conditions, and consists of a pair of bead parts, a wide part connected to these bead parts, and a tread that spans both side parts. a center groove located on the equatorial plane and extending in the circumferential direction; and two areas extending along the center groove on both sides of the center groove and divided by the center groove. A rally round tire having a pair of side grooves that divide approximately equally, a large number of lateral grooves that extend to intersect the center groove and the side grooves, and a large number of blocks that are divided by the center groove, the side grooves, and the lateral grooves, The center groove and the side grooves run directly over substantially the entire circumference of the tire, and each of the lateral grooves has a zigzag shape, so that adjacent blocks in the rotational axis direction of the tire are offset in the circumferential direction, and each block is This round rally tire is characterized by having an auxiliary groove formed at one end located approximately at the center of the block and at the other end opening into a side groove.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a plan view of the tread portion of the tire shown in FIG.

In FIG. 1, a rally tire 1 includes a pair of annular bead portions 2, a side portion 3 connected to these bead portions 2,
A substantially cylindrical tread portion 4 spanning between both side portions;
It is equipped with

Each bead part 2 has a beat wire 2 at its tip position.
' is buried.

Further, in this embodiment, the space between them is reinforced with a carcass 5 of l or a few plies in which fiber cords are arranged in the radial direction of the tire 1.

For the tread portion 4, non-extensible cords, such as steel cords, are arranged by a conventional method so as to intersect at a small angle with respect to the circumferential direction of the tire 1, and a plurality of 1-ru plies are superimposed so that the cords intersect between the plies. Belt layer 6
are arranged over the entire width of the tread portion 4, and the entire periphery of these reinforcing belt layers 6 is covered with the outer cover rubber 1.

The tread surface of the tread portion 4 has one center groove 8 located on the equatorial plane 0-0 of the tire 1 and extending in the circumferential direction of the tire 1, and a center groove 8 extending along the center groove 8 on both sides of the center groove 8. ,
In other words, in the circumferential direction, there is a pair of side grooves 9 that divide approximately equally in area two areas T1 and T2 that extend and are divided by the center groove 8, and a large number of side grooves that extend to intersect with the center groove 8 and the side grooves 9. It has a zigzag-shaped horizontal groove 10.

Here, the zigzag shape includes a shape in which the refraction angle is not constant and the distance between the refraction points is not constant.

By forming the center groove 8, side grooves 9, and lateral grooves 10 on the tread surface of the tread portion 4 as described above, a large number of protruding blocks 11 are generated.

Auxiliary grooves 12a and 12b are formed in the block 11a on the side closer to the center groove 8 and the block 11b on the side closer to the tread edge e, respectively, and these auxiliary grooves 12a
, 12b has one end located in the center of the blocks lla and 11b, and the other ends facing each other and opening into the side groove 9.

Moreover, this auxiliary groove 12a. 12b are arranged on the same straight line.

Both the center groove 8 and the side grooves 9 extend directly over substantially the entire circumference of the tire 1.

That is, both the center groove 8 and the side grooves 9 have a communicating annular groove portion that does not allow the protruding portion to enter.

In this embodiment, the center groove 8 is completely straight through its entire width.

On the other hand, in the side groove 9, the block 11a and the block 11b have different boundary widths with the auxiliary groove 12 as a boundary.

That is, each side groove 9 is made up of a first element 9a parallel to the equatorial plane 0-0 of the tire 1, and a second element 9b extending from the first element 9a toward the rotational axis direction of the tire 1. There is.

As a result, when looking at each gutter 9 as a whole, the second element 9b
This means that it is bent in a crank shape by a length G, σ in the direction of the rotational axis.

When the width of each side groove 9 is F, a portion having a width E communicates over the entire circumference of the tire 1.

Regarding this point, the inventor's experimental results show that it is essential that each side groove 9 is bent into a crank shape by adding a second element 9b, and that the length G of this second element 9b is
, G' is the width E mentioned above.

In addition, like the side groove 9, the center groove 8 may also be bent.

The other end of the auxiliary groove 12 opens at the bent portion of the side groove 9.

As a result, even if the width E is made small, the width F of the side groove 9 does not become locally narrow due to the partial involvement of the lateral groove 10, and the performance described below is not impaired.

Each horizontal groove 10 is a side surface 13a of a block 11a having a chevron shape.
, 14a and the side surfaces 15a and 16a of the block 11a that extend parallel to and opposite to these both sides, and the side surfaces 15b and 13b of the block 11b that extend parallel to the side surface 14a and 16a of the bronze/711a, respectively. During the
Furthermore, it extends in a zigzag shape between the side surfaces 16b and 14b of the block 11b, which extends while being bent with respect to the both side surfaces 15b and 13b.

In this way, since each lateral groove 10 is bent in a zigzag shape, the blocks 11a are adjacent to each other in the direction of the rotation axis of the tire 1.

11b are shifted from each other in the circumferential direction, that is, they are offset.

Then, at the zigzag bending position of each lateral groove 10, between the center groove 8 and the side groove 9, and between the side groove 9 and the tread edge e.
It is approximately in the middle between the two.

An angle of intersection θ1. Both θ2 are preferably in the range of 15 degrees to 30 degrees.

In addition, in this embodiment, especially the side surfaces 16b and 14b
The intersection angle between the center line J of the lateral groove 10 and the straight line M is smaller than the intersection angle θ1°θ2.

Further, in this embodiment, although not shown in detail, the extending direction of the side surface 16b is substantially parallel to the rotation axis direction of the tire 1.

As a result, the lateral groove 10 has a deformed zigzag shape.

Further, the lateral groove 10 at the opening end adjacent to the center groove 8
The groove width B measured in the circumferential direction, that is, parallel to the equatorial plane 0-0, is preferably in the range of 0.15 to 0.3 times the pitch length A of the pattern in the block 11a row.

Further, the lateral groove 10 at the opening end close to the tread edge e
It is preferable that the groove width C measured in the circumferential direction is wider than the groove width B.

Moreover, in this case, the pitch length A is 02 to 0.04 times the tread circumference (g).

Each of the lateral grooves 10 is composed of a lateral groove 10a on one side of the center groove 8 and a lateral groove 10b on the other side of the center groove 8, and the center lines J of these lateral grooves 10a and 10b are offset in the circumferential direction. has been done.

In other words, the lateral grooves 10a and 10b open into the center groove 8 at different angles from each other.

Therefore, each lateral groove 10 is bent in a crank shape at the center groove 8 portion, and the lateral groove portions 10a and 10b communicate with each other via a portion of the center groove 8.

Note that the center lines J of the lateral grooves 10a and 10b may be arranged on the same straight line.

The auxiliary groove 12a. 12b is in this example:
Block 11a.

Extending in parallel with the side surfaces 14a and 15b of 11b, respectively,
Moreover, as described above, they are arranged in a straight line.

However, as long as the purpose is not impaired, they may not be arranged on a single straight line, but their center lines may be shifted from each other.

Width D1 of the auxiliary grooves 11a and 11b measured in the circumferential direction. D2
is preferably narrower than the lateral groove width B, and more preferably ranges from 0.55 times to 0.75 times the lateral groove width B.

FIG. 3 is a plan view of the tread portion of another embodiment of the rally tire according to the present invention.

A feature of this embodiment is that a cutout 37 is formed on the side surface of the block 31a facing the center groove 28, and this cutout 3
One side 38 of the block 31a is placed near the equatorial plane 0-0 with T as the boundary, and the other side 38 of the block 31a is placed near the equatorial plane 0-0.
9 is placed away from the equatorial plane 0-0.

Therefore, the center groove 28 is bent and extends in a crank shape, similar to the side groove 9 shown in FIG.

Regarding the lateral groove 30, block 1 in the above-mentioned embodiment
Side 16b of 1b.

Deformed side surfaces 36b and 34b having another bent portion are formed at a portion corresponding to 14b.

As a result, the lateral groove 30 has a deformed zigzag shape.

The block 31b also has an auxiliary groove 32b at its center position.
It has an enlarged space 40 continuous with the tread edge e, and a cutout portion 41 facing the tread edge e.

A large number of cuts 42 (sipes) are formed in each block 31a, 31b.

The tire of the present invention thus constructed has a tread that is divided into three approximately equal parts, unlike a tread that is made up of a large number of small blocks that have been conventionally used as rally tires.
A block having appropriate rigidity is divided by a center groove based on the straight line of the book, side grooves, and a large number of zigzag horizontal grooves arranged in a direction intersecting these grooves.

In this case, since the lateral grooves are shaped like force curves, the blocks, which are thicker than conventional blocks, are arranged in a meandering direction in the direction of the rotational axis of the tire, which is especially important when driving on rough roads. When force) is applied, the side of the block perpendicular to this lateral force increases,
Works in your favor.

In addition, although the block is larger than the conventional rally tire, it can effectively maintain a large space especially in the area where the center groove, side groove and auxiliary groove intersect, so it can be used on rough roads, especially on muddy areas. It is advantageous in terms of ground grip power.

On the other hand, when driving on paved roads, the crank-shaped bending of the side grooves increases the surface area of the block perpendicular to the direction of action of the driving and braking forces, which is advantageous, and at the same time, the center grooves and side grooves of the tire Since it has a part that runs directly in the circumferential direction, it has excellent drainage performance when driving at high speed on wet roads.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a one-round rally tire according to the present invention, FIG. 2 is a plan view of the tread portion of the tire shown in FIG. 1, and FIG. 3 is a one-round rally tire according to the present invention. FIG. 3 is a plan view of a tread portion of another embodiment of the tire. 1 is a rally tire, 2 is a bead part, 3 is a side part, 4
is a tread portion, 8 is a center groove, 9 is a side groove, 10 is a lateral groove, 12 is an auxiliary groove, and 0-0 is an equatorial plane.

Claims (1)

[Scope of Claims] 1 Consists of a pair of bead portions, side portions connected to these bead portions, and a tread portion spanning (crossing) both side portions, the tread portion being located on the equatorial plane and extending around the circumference. a center groove that extends in the direction; a pair of side grooves that extend along the center groove on both sides of the center groove and roughly equally divide the two areas divided by the center groove; In a rally tire having a large number of extending lateral grooves and a large number of blocks divided by the center groove, side grooves, and lateral grooves, the center groove and the side grooves run directly over substantially the entire circumference of the tire, and each of the lateral grooves The blocks that are adjacent to each other in the rotational axis direction of the tire are shifted in the circumferential direction by exhibiting a zigzag shape, and the adjacent blocks have one end located approximately at the center of the block and the other end located in the side groove. A pair of opening auxiliary grooves are formed via a side groove, and the block widths of the auxiliary grooves are made different at the front and rear of the husband block so that the side groove is bent in a crank shape at the position of the auxiliary groove. 2. A first element in which the side groove is parallel to the equatorial plane of the tire;
and a second element extending from the first element substantially in the direction of the rotational axis of the tire, and the one-round rally tire according to claim 1, which is continuous in a crank shape as a whole. 3. The rally tire according to claim 1 or 2, wherein each of the lateral grooves has a zigzag bent portion located approximately at the center between the center groove and the side groove and between the side groove and the tread edge. 4 Intersection angle θ1 between the center line of the lateral groove located between the center groove and the side groove and a straight line that is parallel to the rotational axis of the tire and intersects with the center line. The rally tire according to claim 3, wherein both θ2 are in the range of 15 degrees to 30 degrees. 5. Claim L2, wherein the width C measured in the circumferential direction of the lateral groove at the end near the tread edge is wider than the width B measured parallel to the circumferential direction of the lateral groove at the end near the center groove,
The rally tire according to any one of item 3. 6. One round of the rally according to claim 1, wherein the lateral grooves on one side of the center groove and the lateral grooves on the other side of the center groove are offset in the circumferential direction, and these lateral grooves communicate via the center groove. tire. T. The rally one-round tire according to claim 1, wherein the auxiliary groove is arranged on the tank tank so as to be located on a straight line. 8. A patent claim in which the width of the auxiliary groove measured parallel to the circumferential direction is within a range of 0.5 to 0.75 times the width B measured parallel to the circumferential direction of the lateral groove at the end adjacent to the center groove. The range of Rally tires described in item 1.