KR20180125891A - Tire - Google Patents

Abstract

The present invention relates to a tire capable of improving water drain properties and preventing a decrease in steering stability. A tire (1) has a fixed rotational direction (R). In a tread portion (2), a main groove (3) extends in a zigzag manner. The main groove (3) includes an inclination element (5) and an axial element (6) alternately arranged in the circumferential direction of the tire. The inclination element (5) is inclined axially outward while being directed toward the rear side of the rotational direction (R). The axial member (6) extends from the rear side of the rotational direction (R) of the inclination element (5) to the axial direction of the tire to allow a groove wall, which is positioned on an outer side portion of the axial direction of the tire and on the rear side of the rotational direction (R), to collect water in front of a tread when the tire is running. The maximum width (Wb) of the axial element (6) is greater than the maximum width (Wa) of the inclination element (5).

Description

Tire {TIRE}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a tire in which main grooves continuously extending in a staggered manner are formed in a tread portion.

BACKGROUND ART Conventionally, in order to improve the drainage performance of a tire, it has been known that the width and depth of the main groove are increased as a whole to increase the groove volume. However, if the groove volume is increased, there is a problem that the grounding area is reduced and the rigidity of the land portion is lowered, and the steering stability performance on a dry road surface is lowered.

Particularly, in a race tire running at high speed and high load, it has been required to improve the drainage performance while securing the rigidity of the land portion in order to generate a large cornering force.

Patent Document 1: JP-A-2016-97779

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a tire capable of improving drainage performance while suppressing deterioration of steering stability performance.

The tread portion is formed with at least one main groove continuously extending in a staggered manner in a tire circumferential direction at a position away from a tire equator, , The inclined element and the axial element alternately in the tire circumferential direction, and the inclined element extends obliquely outwardly in the tire axial direction toward the rear side in the rotational direction, and the axial element Is formed so as to extend in the tire axial direction from the back side of the tilted element in the rotational direction so that the outer side portion in the axial direction of the tire and the groove wall positioned on the trailing side in the rotating direction scrape off the water in front of the tread And the maximum width of the axial element is formed larger than the maximum width of the inclined element.

In the tire according to the present invention, it is preferable that the axial element extends at an angle of 10 DEG or less with respect to the tire axial direction.

In the tire according to the present invention, it is preferable that the axial element extends at an angle of 0 DEG with respect to the axial direction of the tire, or is inclined toward the tire equatorial side toward the first attachment side in the rotational direction.

In the tire according to the present invention, it is preferable that an inner portion of the axial element in the axial direction of the axial element gradually increases in width toward the inner side in the axial direction of the tire.

In the tire according to the present invention, it is preferable that, in the tread portion, an inner lateral groove extending inwardly in the tire axial direction is formed continuously with the axial element at one end.

In the tire of the present invention, it is preferable that the other end of the inner lateral groove is terminated without communicating with other grooves.

The tire according to the present invention is characterized in that the tread portion has a land portion inside the tire axial direction of the main groove and the land portion has a corner portion sandwiched between the inclined element and the inner portion in the tire axial direction of the axial element And the corner portion is formed with a chamfered portion formed by a slope that descends toward the main groove.

In the tire according to the present invention, it is preferable that in the tread portion, an outer lateral groove is formed, one end of which is continuous with the axial element and extended outward in the tire axial direction.

In the tire of the present invention, it is preferable that the depth of the outer lateral groove is smaller than the depth of the main groove.

According to the present invention, the inclined elements of the main groove can be drained to the outside in the tire axial direction by using the rotation of the tire. Further, the axial element of the main groove is such that the groove wall in the rotational direction on its rearward side scrapes and holds water in front of the tread at the time of running the tire, and discharges it to the rear of the tire when the axial element is separated from the road surface. At this time, since the axial elements have a maximum width larger than the inclined elements, more water can be stored and discharged to the rear. Such a series of actions is realized without increasing the groove volume of the main groove, so that remarkable deterioration of the steering stability performance is suppressed.

1 is an exploded view of a tread portion of a pneumatic tire according to an embodiment of the present invention.
2 is an enlarged view of the main groove of Fig.
3 is an exploded view of the left half of the tread portion of another embodiment.
4 is an enlarged view of a main groove according to another embodiment.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

1 is an exploded view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. In this embodiment, as a preferred embodiment, a pneumatic tire for racing used for circuit traveling and the like is shown. However, the present invention can also be applied to tires of other categories such as tires for heavy loads such as tires for passenger cars, trucks and buses, and airless tires.

As shown in Fig. 1, the tread portion 2 of the tire 1 of the present embodiment has a directional pattern in which the rotational direction R is specified. The rotation direction R is displayed on a sidewall (not shown), for example, with a character or the like.

The tread portion 2 of the present embodiment is provided with at least one main groove 3 continuously extending in a staggered manner in the tire circumferential direction at a position remote from the tire equator C and a A land portion 4 is formed.

In the present embodiment, one main groove 3 is formed on each side of the tire equator C, respectively. The main groove 3 is not limited to such an embodiment, and may be a plurality of the main grooves 3 on both sides of the tire equator C, for example. In the present embodiment, the zigzag pitches of the main grooves 3, 3 in the tire circumferential direction are the same, but the pitch may deviate from the tire circumferential direction.

The land portion 4 of this embodiment has a shoulder land portion 4A disposed between the main groove 3 and the tread edge Te and a crown land portion 4B disposed between the main grooves 3, ).

The " tread edge " Te is a tire 1 that is rimmed in a regular rim and filled with a normal internal pressure and loaded in a normal state, Is set as the outermost ground position. In the normal state, the distance in the tire axial direction between the both tread Te and Te is defined as the tread width TW. Unless otherwise stated, the dimensions and the like of each part of the tire 1 are values measured in a normal state.

Quot; standard rim "in the case of JATMA," Design Rim "in the case of TRA, and" Measuring Rim " in the case of ETRTO in the standard system including the standard conforming to the tire, "to be.

"Normal pressure" refers to the air pressure that is determined for each tire according to each standard in the standard system that includes the standard to which the tire is subjected. "TRIP" is the maximum air pressure for JATMA, "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" Quot; INFLATION PRESSURE "in the case of ETRTO. When the tire is for passenger cars, the normal internal pressure is 180 kPa.

The "normal load" is a load determined for each tire according to each standard in the standard system including the standard to which the tire is subjected, and "maximum load capacity" in the case of JATMA, "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES Quot ;, and " LOAD CAPACITY "in the case of ETRTO. If the tire is for passenger cars, the normal load is a load corresponding to 88% of the load.

Fig. 2 is an enlarged view of the main groove 3. Fig. As shown in Fig. 2, the main groove 3 alternately includes the inclined element 5 and the axial element 6 in the tire circumferential direction in the present embodiment. The inclined element 5 is, in the present embodiment, a groove-shaped portion that is inclined at a larger angle? 1 with respect to the axial direction of the tire than the axial element 6.

The inclined element 5 has an outer groove wall 7a extending in the tire circumferential direction and disposed on the side of the tread edge Te and an outer groove wall 7b extending in the tire circumferential direction and on the tire equator C side And an inner groove wall 7b disposed therein. The outer groove wall 7a and the inner groove wall 7b are inclined to one side with respect to the tire circumferential direction in the present embodiment.

The axial element 6 includes a fastening side groove wall 8a located on the fastening side in the rotation direction R and a first arrival side groove wall 8b located on the fastening side in the rotation direction R . The fitting side groove wall 8a is continuous with the outer groove wall 7a in the present embodiment. The first arrival side groove wall 8b is continuous with the inner groove wall 7b in the present embodiment.

The axial element 6 in the present embodiment is composed of an imaginary terminating end 9a including the trailing side groove wall 8a and smoothly extending the trailing side groove wall 8a inward in the tire axial direction, And a virtual forehead end 9b including the groove wall 8b and smoothly extending the groove edge of the first arrival side groove wall 8b outward in the tire axial direction.

The axial element 6 includes an outer portion 10a and an inner portion 10b in the tire axial direction in the present embodiment. The outer portion 10a of the present embodiment includes a first arrival side groove wall 8b. The inner portion 10b of the present embodiment includes a back side groove wall 8a.

The inclined element 5 extends obliquely outwardly in the tire axial direction toward the back side in the rotation direction R. This inclined element 5 can drain the water film between the road surface and the road surface 4a of the land portion 4 outwardly in the tire axial direction by using the rotation of the tire 1. [

The axial element 6 is an outer portion 10a in the axial direction of the tire and the trailing side groove wall 8a extends in the axial direction of the tire from the back side of the rotational direction R of the tilting element 5. Thus, the trailing side groove wall 8a scrapes and holds the water in front of the tread at the time of running the tire, and discharges it to the rear of the tire when the axial element 6 is separated from the road surface.

The maximum width Wb of the axial element 6 is formed to be larger than the maximum width Wa of the inclined element 5. [ As a result, more water can be stored and discharged backward. Therefore, the tire 1 of the present embodiment has improved drainage performance. Further, since such an action is realized without increasing the groove volume of the main groove 3, remarkable deterioration of the steering stability performance is suppressed.

If the maximum width Wb of the axial element 6 is formed to be larger than the maximum width Wa of the inclined element 5, the groove volume becomes large and the rigidity of the shoulder land portion 4A or the crown land portion 4B is lowered There is a concern. For this reason, it is preferable that the maximum width Wb of the axial element 6 is about 1.3 to 2.5 times the maximum width Wa of the inclined element 5.

The maximum width Wa of such inclined elements 5 is preferably 1.5% to 5.0% of the tread width TW, for example.

The inclined element 5 and the axial element 6 are linear in this embodiment and extend in the same width along the longitudinal direction. The inclined element 5 and the axial element 6 improve drainage because the drain resistance is small. Further, since the lowering of the rigidity of the land portion 4 is suppressed, the steering stability performance is kept high.

The angle? 1 of the inclined element 5 is preferably 65 ° or more. If the angle? 1 of the inclined element 5 is less than 65 占 the water in the inclined element 5 may not be smoothly removed. In this specification, the angle of the groove of the inclined element 5, etc. is defined as a groove center line which is formed subsequently to the intermediate position of the groove width.

In this embodiment, the corner portion 11A of the shoulder land portion 4A sandwiched between the inclined element 5 and the outer portion 10a of the axial element 6 and the corner portion 11A of the inclined element 5 and the axial element 6 The corner portion 11B of the crown land portion 4B sandwiched between the inner portions 10b of the crown land portion 4 is formed.

The axial element 6 preferably extends at an angle? 2 of 10 degrees or less with respect to the axial direction of the tire. Since the corner portions 11A and 11B are formed at an acute angle when the angle? 2 of the axial element 6 exceeds 10 ° toward the tire equator C side in the rotational direction R, 4) becomes small and the steering stability performance may deteriorate. When the angle alpha 2 of the axial element 6 exceeds 10 degrees toward the rear side of the rotation direction R toward the tire equator C side, water scraped from the back side groove wall 8a is drawn into the back side groove wall 8a to the slanting element 5 on the back side in the rotation direction R, so that the water can not be held in the axial element 6. [

The axial element 6 is inclined at an angle? 2 with respect to the axial direction of the tire or inclined toward the tire loading side in the rotational direction R toward the tire equator C side in order to effectively exert the above- .

Particularly preferably, the angle? 1 with respect to the tire axial direction of the groove edge of the trailing groove wall 8a is 0 ° and is 10 ° or less toward the tire equator C side in the rotational direction R desirable.

The trailing side groove wall 8a of the present embodiment preferably intersects with the virtual edge 7e which smoothly extends the inner groove wall 7b toward the back side of the rotation direction R. [ This end wall groove 8a is resistant to the scraped water and smoothly guides and holds the water to the inner portion 10b so that the effect of draining the water behind the tire of the axial element 6 .

The groove edge of the first arrival side groove wall 8b extends in parallel with the second groove side wall 8a in the present embodiment. The first arrival side groove wall 8b maintains a good balance between the rigidity of the corner portion 11B of the crown land portion 4B and the holding force of the water of the axial element 6. [ The groove edge of the first arrival side groove wall 8b is not limited to such an embodiment and may be inclined to an arcuate shape or to a back side of the tire equator C in the rotational direction R, But may be inclined at a larger angle with respect to the tire axial direction than the trailing side groove wall 8a.

1, the tire axial distance La between the zigzag amplitude center line 3c of the main groove 3 and the tire equator C is preferably 10% or more of the tread width TW, more preferably 15% or more , More preferably 30% or less, and still more preferably 25% or less. By arranging the main groove 3 at such a position, the rigidity of the shoulder land portion 4A in the axial direction of the tire can be increased and a large cornering force can be generated, so that excellent steering stability performance is maintained. In addition, the water film between the road surface and the road surface 4a of the land portion 4 can be effectively removed on the tire equator C side, which is relatively difficult to drain.

The groove depth (not shown) of the main groove 3 is preferably 4 to 10 mm, for example. The groove depth of the inclined element 5 is preferably 80% to 125% of the groove depth of the axial element 6, and in the present embodiment, The depth and the groove depth of the axial element 6 are formed identically.

3 is an exploded view of the left half of the tread portion 2 of another embodiment of the present invention. The same components as those shown in Figs. 1 and 2 are denoted by the same reference numerals, and a description thereof will be omitted. As shown in Fig. 3, the tread portion 2 of this embodiment is formed with an inner lateral groove 12, one end of which is continuous with the axial element 6 and extends inward in the tire axial direction. This inner lateral groove 12 enhances drainage performance.

The other end of the inner lateral groove 12 is terminated without communicating with other grooves. As a result, the lowering of the rigidity of the crown land 4B to which the large ground pressure acts is suppressed, so that the deterioration of the steering stability performance is suppressed. In this embodiment, since the inner lateral groove 12 is terminated without reaching the tire equator C, the above-described action is effectively exerted.

Although not particularly limited, it is preferable that the groove width W1 of the inner lateral groove 12 is about 80% to 125% of the maximum width Wb of the axial element 6. [ The groove depth of the inner lateral groove 12 is preferably about 80% to 125% of the groove depth of the main groove 3. The length Lc of the inner lateral groove 12 in the axial direction of the tire is preferably about 80% to 125% of the maximum width Wa of the inclined element 5. [

Further, in this embodiment, the axial element 6 includes an inner portion 10b whose width W2 gradually increases toward the inner side in the tire axial direction. In this axial element 6, more water can be stored. In this specification, the inner portion 10b in which the width W2 gradually increases is referred to as an increment portion 13 hereinafter.

In this embodiment, the corner portion 11B of the crown land portion 4B is formed with a chamfered portion 14 composed of a slope 14a that descends toward the main groove 3. This chamfered portion 14 improves the water holding ability of the axial element 6 and suppresses the decrease in the rigidity of the land portion of the corner portion 11B so that the drainage performance and the steering stability performance are well balanced Can be improved. In this embodiment, the chamfered portion 14 is formed in a triangular shape in plan view.

Further, in this embodiment, the outer lateral grooves 16, one end of which extends continuously to the axial direction outer side of the axial element 6, are formed. Thus, the drainage performance is improved. The outer lateral grooves 16 are continuous with the tread Te in this embodiment.

The depth (not shown) of the lateral grooves 16 is preferably smaller than the depth of the main grooves 3. Thus, since the lowering of the rigidity of the shoulder land portion 4A is suppressed, the steering stability performance is maintained at a high level. Further, since a stepped groove bottom (not shown) is formed between the outer lateral grooves 16 and the axial element 6, this stepped groove bottom can prevent the water retention effect of the axial element 6 Reduce the reduction.

The groove depth of the outer lateral groove 16 is preferably 20% or more and preferably 60% or less of the groove depth of the main groove 3 in order to effectively exhibit the above-described action.

3 shows a pattern including both the inner lateral grooves 12, the incrementing portions 13, the chamfered portions 14, and the outer lateral grooves 16. [ However, the present invention is not limited to these embodiments. The present invention can be applied to any one of the inner lateral grooves 12, the incremental portions 13, the chamfered portions 14 and the outer lateral grooves 16 or a plurality of patterns selected from the inner lateral grooves 12, .

Fig. 4 shows a main groove 3 according to another embodiment of the present invention. The same components as those shown in Figs. 1 and 2 are denoted by the same reference numerals, and a description thereof will be omitted. As shown in Fig. 4, in this embodiment, the inclined elements 5A are formed in a convex arc shape toward one side of the tire axial direction, for example, toward the tire equator C side. This inclined element 5A has a larger groove volume than the linearly extending inclined elements 5, and thus can save a large amount of water, thereby improving drainage performance.

The inclination element 5A of the present embodiment gradually decreases the angle? 1 with respect to the tire axial direction from the first attachment side to the second attachment side in the rotation direction R. This inclined element 5A makes it easier to hold the water in the axial element 6 because it slows down the flow of the water flowing in the inclined element 5A toward the back side of the rotation direction R. [ Therefore, the tire 1 of this embodiment has excellent drainage performance.

Although the embodiments of the present invention have been described in detail above, it is needless to say that the present invention is not limited to the embodiments, but can be modified in various ways.

[Example]

Pneumatic tires of size 245 / 40R18 having the basic pattern of Fig. 1 were tested and manufactured based on the specifications of Table 1, and the steerability and drainage performance of each construction tire were tested. The main common specifications and test methods of each construction tire are as follows.

Groove depth of main groove (inclined element and axial element): 6 mm

Maximum width of taper element Wa: 10 mm (3.2% of tread width)

Angle of inclined element θ1: 80 °

&Quot; Parallel to the trailing side groove wall " in Table 1 means that the groove edge of the first arrival side groove wall extends parallel to the groove edge of the trailing side groove wall

Means that the groove edge of the first arrival side groove wall is inclined toward the back side of the rotation direction R toward the tire equator C side

The numerical values of? 1 in Table 1 indicate "the positive side" in the rotational direction toward the tire equator side and the "negative" side in the same rotational direction.

The groove volumes of the axial elements of Examples 1, 10 and 11 are the same.

<Steering stability performance>

Each of the construction tires was mounted on the front wheels of the four-wheel drive vehicle for racing with a displacement of 2000 cc under the following conditions. Then, the test driver ran the test course of the dry asphalt road surface, and the steering stability performance including the steering wheel responsiveness, the stiffness feeling, the grip and the like at this time was evaluated by sensory (sensory). The result is indicated by a score of 100 in Comparative Example 1. The larger the number, the better.

Rim: 18 × 8.5 J

Withstand pressure: 200 kPa

<Drain performance>

A lateral acceleration (lateral G) acting on a front wheel when a test course of an asphalt road surface with a radius of 100 m formed with a puddle of 2 mm in depth was made using the above vehicle. The result is indicated by an index showing the value of Comparative Example 1 as 100 by using an average lateral G (lateral / hydroplaning test) when the vehicle speed is 50 to 80 km / h. The larger the number, the better.

The results of the test are shown in Table 1.

As a result of the test, it was confirmed that the tires of the examples were improved in drainage performance while suppressing the deterioration of the steering stability performance, as compared with the tires of the comparative example.

1: Tire
2: tread portion
3: Main Home
5: Slope element
6: Axial element
8a: Home wall
R: Direction of rotation
Wa: Maximum width of the slant element
Wb: Maximum width of axial element

Claims (9)

A tire having a tread portion whose rotational direction is designated,
The tread portion is formed with at least one main groove continuously extending in a zigzag fashion in a tire circumferential direction at a position away from the tire equator,
The main groove alternately includes a tapered element and an axial element in the tire circumferential direction,
Wherein the inclined element extends obliquely outwardly in the tire axial direction toward a back side of the tire in the rotational direction,
Wherein the axial element is a torsion spring that is disposed on the rear side of the tread element in the rotational direction of the tread element so as to scrape water in front of the tread at the time of running the tire, Extending in the axial direction,
Wherein a maximum width of the axial elements is formed larger than a maximum width of the inclined elements. The tire according to claim 1, wherein the axial element extends at an angle of not more than 10 degrees with respect to the axial direction of the tire. The tire according to claim 1, wherein the axial element extends at 0 占 with respect to the axial direction of the tire, or is inclined toward the tire equatorial side toward the first attachment side in the rotational direction. The tire according to any one of claims 1 to 3, wherein an inner portion of the axial element in the axial direction of the axial component gradually increases in width toward the inner side in the axial direction of the tire. The tire according to any one of claims 1 to 4, wherein the tread portion is formed with an inner lateral groove extending inwardly in the tire axial direction, one end of which is continuous with the axial element. The tire according to claim 5, wherein the other end of the inner lateral groove is terminated without communicating with another groove. 7. The tire according to any one of claims 1 to 6, wherein the tread portion has a land portion inside the tire axial direction of the main groove,
Wherein the land portion has a corner portion sandwiched between the inclined element and an inner portion in the tire axial direction of the axial element,
Wherein the corner portion is formed with a chamfered portion formed by a slope that descends toward the main groove. 8. The tire according to any one of claims 1 to 7, wherein the tread portion is formed with an outer lateral groove whose one end is continuous with the axial element and which extends outwardly in the tire axial direction. The tire according to claim 8, wherein a depth of the outer lateral groove is smaller than a depth of the main groove.

Images