JP2018192875A - tire - Google Patents

Abstract

To provide a tire that can improve drainage performance while suppressing deterioration in steering stability performance.SOLUTION: A tread part of a tire in which a rotation direction R is specified is provided with a main groove 3 extending zigzag. The main groove 3 includes oblique elements 5 and shaft-directional elements 6 alternately arranged in a tire circumferential direction. The oblique elements 5 obliquely extend toward outside in a tire shaft direction, toward a last-come side in the rotation direction R. The shaft-directional elements 6 extend in a tire shaft direction from the last-come side in the rotation direction R of the oblique elements 5 so that a groove wall 8a positioned at an outer part in the tire shaft direction and at the last-come side in the rotation direction R can scrape out water in front of a tread in tire-travelling, which are formed so that the maximum width Wb of the shaft-directional elements 6 is larger than the maximum width Wa of the oblique elements 5.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tire in which a main groove extending continuously in a zigzag shape is provided in a tread portion.

  Conventionally, in order to improve the drainage performance of a tire, it is known to increase the groove volume by increasing the width and depth of the main groove as a whole. However, when the groove volume is increased, there is a problem that the ground contact area is reduced and the rigidity of the land portion is reduced, and the steering stability performance on the dry road surface is lowered.

  In particular, in racing tires that run at high speeds and high loads, in order to generate a large cornering force, it has been desired to improve drainage performance while securing rigidity of land portions.

Japanese Patent Application Laid-Open No. 2006-97779

  The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire capable of improving drainage performance while suppressing a decrease in steering stability performance.

  The present invention is a tire having a tread portion whose rotation direction is designated, and the tread portion has at least one main groove extending continuously in a zigzag manner in a tire circumferential direction at a position away from the tire equator. The main groove includes inclined elements and axial elements alternately in the tire circumferential direction, and the inclined elements are inclined outward in the tire axial direction toward the rear arrival side in the rotational direction. The axial element is configured so that the groove wall located on the outer portion in the tire axial direction and on the rearward side in the rotational direction scrapes off the water in front of the tread when the tire is running. It extends in the tire axial direction from the rear arrival side in the rotational direction, 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, the axial element preferably extends at an angle of 10 ° or less with respect to the tire axial direction.

  In the tire according to the present invention, it is desirable that the axial element extends at 0 ° with respect to the tire axial direction, or is inclined toward the first arrival side in the rotational direction toward the tire equator side.

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

  In the tire according to the present invention, it is desirable that the tread portion is provided with an inner lateral groove having one end connected to the axial element and extending inward in the tire axial direction.

  In the tire according to the present invention, it is desirable that the other end of the inner lateral groove terminates without communicating with another groove.

  In the tire according to the present invention, the tread portion has a land portion on the inner side in the tire axial direction of the main groove, and the land portion includes the inclined element and an inner portion in the tire axial direction of the axial direction element. It is preferable that the corner portion has a sandwiched corner portion, and the corner portion is provided with a chamfered portion formed of an inclined surface descending toward the main groove.

  In the tire according to the present invention, it is desirable that the tread portion is provided with an outer lateral groove having one end connected to the axial element and extending outward in the tire axial direction.

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

  According to the present invention, the inclined element of the main groove can be drained to the outer side in the tire axial direction by utilizing the rotation of the tire. In addition, the axial element of the main groove is configured such that the groove wall on the rear side in the rotational direction scrapes and holds water in front of the tread when the tire travels, and the rearward of the tire when the axial element is separated from the road surface. Discharge. In this case, the axial element has a larger maximum width than the inclined element, so that more water can be stored and discharged backwards. Since these series of actions are realized without increasing the groove volume of the main groove, a significant decrease in steering stability performance is suppressed.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. It is an enlarged view of the main groove of FIG. It is an expanded view of the left half of the tread part of other embodiment. It is an enlarged view of the main groove of other embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. In the present embodiment, as a preferable aspect, a pneumatic tire for racing used for circuit running or the like is shown. However, it goes without saying that the present invention can also be applied to tires of other categories such as heavy duty tires such as passenger car tires and 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 rotation direction R is designated. The rotation direction R is displayed with characters or the like on a sidewall portion (not shown), for example.

  The tread portion 2 of the present embodiment includes at least one main groove 3 continuously extending in a zigzag shape in the tire circumferential direction at a position away from the tire equator C, and a land portion 4 partitioned by the main groove 3. Is provided.

  In the present embodiment, one main groove 3 is provided on each side of the tire equator C. In addition, the main groove 3 is not limited to such an aspect, For example, the aspect provided with two or more on both sides of the tire equator C may be sufficient. In the present embodiment, the main grooves 3 and 3 have the same zigzag tire circumferential pitch, but the pitch may be shifted in the tire circumferential direction.

  The land portion 4 of the present embodiment includes a shoulder land portion 4A disposed between the main groove 3 and the tread end Te, and a crown land portion 4B disposed between the main grooves 3 and 3. .

  The “tread end” Te is the most when the normal load 1 is loaded with the normal rim and is loaded with the normal internal pressure, and the normal load is applied to the flat tire with a camber angle of 0 degree. It is determined as a contact position on the outer side in the tire axial direction. In the normal state, the distance in the tire axial direction between the tread ends Te and Te is determined as the tread width TW. When there is no notice in particular, the dimension of each part of the tire 1 is a value measured in a normal state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, ETRTO Then "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “maximum air pressure”, TRA is the table “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO. When the tire is for a passenger car, the normal internal pressure is 180 kPa.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “maximum load capacity”, TRA is “TIRE LOAD” The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO. When the tire is for a passenger car, the normal load is a load corresponding to 88% of the load.

  FIG. 2 is an enlarged view of the main groove 3. As shown in FIG. 2, the main groove 3 includes inclined elements 5 and axial elements 6 alternately in the tire circumferential direction in this embodiment. In the present embodiment, the inclination element 5 is a groove-like portion that is inclined at an angle α1 greater than the axial element 6 with respect to the tire axial direction.

  In the present embodiment, the inclined element 5 includes an outer groove wall 7a extending in the tire circumferential direction and disposed on the tread end Te side, and an inner groove wall 7b extending in the tire circumferential direction and disposed on the tire equator C side. Have. In this embodiment, the outer groove wall 7a and the inner groove wall 7b are inclined to one side with respect to the tire circumferential direction.

  The axial element 6 includes a rear arrival side groove wall 8a located on the rear arrival side in the rotation direction R and a first arrival side groove wall 8b located on the first arrival side in the rotation direction R. In this embodiment, the rear-end groove wall 8a is continuous with the outer groove wall 7a. In this embodiment, the first-side groove wall 8b is continuous with the inner groove wall 7b.

  In the present embodiment, the axial element 6 includes a virtual rear landing end 9a including the rear landing groove wall 8a and smoothly extending the rear landing groove wall 8a inward in the tire axial direction, and a first landing groove wall 8b. It is divided between a virtual first arrival end 9b in which the groove edge of 8b is smoothly extended outward in the tire axial direction.

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

  The inclination element 5 extends while inclining outward in the tire axial direction toward the rear arrival side in the rotation direction R. Such a tilting element 5 can drain the water film between the road surface and the tread surface 4 a of the land portion 4 outward in the tire axial direction by utilizing the rotation of the tire 1.

  In the axial direction element 6, the outer portion 10 a in the tire axial direction and the rearward-side groove wall 8 a extend from the rearward side in the rotational direction R of the inclined element 5 in the tire axial direction. As a result, the rear groove wall 8a scrapes and holds the water in front of the tread when the tire is running, and discharges it toward 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 larger than the maximum width Wa of the tilting element 5. As a result, more water can be stored and discharged backward. Accordingly, the tire 1 of the present embodiment has improved drainage performance. Moreover, since such an effect | action is implement | achieved without the increase in the groove volume of the main groove 3, the remarkable fall of steering stability performance is suppressed.

  When the maximum width Wb of the axial element 6 is formed to be excessively 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 may be reduced. . For this reason, the maximum width Wb of the axial element 6 is desirably about 1.3 to 2.5 times the maximum width Wa of the tilting element 5.

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

  In this embodiment, the inclined element 5 and the axial element 6 are linear and extend with the same width along the longitudinal direction. Since the inclined element 5 and the axial element 6 have a small drainage resistance, the drainage performance is improved. Moreover, since the rigidity fall of the land part 4 is suppressed, steering stability performance is maintained highly.

  The angle α1 of the inclined element 5 is desirably 65 ° or more. When the angle α1 of the inclined element 5 is less than 65 °, the water in the inclined element 5 may not be removed smoothly. In the present specification, the angle of the groove of the inclined element 5 or the like is defined by a groove center line formed by joining the intermediate position of the groove width.

  In the present 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 crown sandwiched between the inclined element 5 and the inner portion 10b of the axial element 6 A corner portion 11B of the land portion 4B is provided.

  The axial element 6 preferably extends at an angle α2 of 10 ° or less with respect to the tire axial direction. When the angle α2 of the axial element 6 exceeds 10 ° on the first arrival side in the rotational direction R toward the tire equator C side, the corner portions 11A and 11B are formed at acute angles, so that the rigidity of the land portion 4 is reduced. The steering stability performance may be reduced. When the angle α2 of the axial element 6 exceeds 10 ° on the rear arrival side in the rotational direction R toward the tire equator C side, the water scraped off by the rear arrival side groove wall 8a along the rear arrival side groove wall 8a. There is a possibility that water may not be retained by the axial element 6 because it flows into the inclined element 5 on the rear arrival side in the rotational direction R.

  In order to effectively exhibit the above-described action, the axial element 6 extends at an angle α2 of 0 ° with respect to the tire axial direction, or is inclined toward the first arrival side in the rotational direction R toward the tire equator C side. It is desirable.

  Particularly preferably, the angle θ1 of the groove edge of the rear arrival side groove wall 8a with respect to the tire axial direction includes 0 ° and is preferably 10 ° or less on the first arrival side in the rotational direction R toward the tire equator C side.

  The rear arrival side groove wall 8a of the present embodiment preferably intersects with a virtual edge 7e obtained by smoothly extending the inner groove wall 7b toward the rear arrival side in the rotation direction R. Such a rear arrival side groove wall 8a becomes the resistance of the scraped water, and smoothly guides and holds the water to the inner portion 10b, so that the draining effect of the axial element 6 to the rear of the tire is improved. .

  In this embodiment, the groove edge of the first arrival side groove wall 8b extends in parallel with the rear arrival side groove wall 8a. Accordingly, the first-side groove wall 8b maintains the rigidity of the corner portion 11B of the crown land portion 4B and the water holding force of the axial element 6 in a well-balanced manner. In addition, the groove edge of the first arrival side groove wall 8b is not limited to such an aspect. For example, the groove edge extends in an arc shape or is inclined toward the rear arrival side in the rotational direction R toward the tire equator C side. Alternatively, it may be inclined at a larger angle with respect to the tire axial direction than the rear arrival side groove wall 8a.

  As shown in FIG. 1, the tire axial direction 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, 30% or less is desirable and 25% or less is more desirable. By arranging the main groove 3 in such a position, the tire land direction portion 4A can be increased in rigidity in the tire axial direction and a large cornering force can be generated, so that excellent steering stability performance is maintained. Further, the water film between the road surface and the tread 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. Although not particularly limited, it is desirable that the groove depth of the inclined element 5 is 80% to 125% of the groove depth of the axial element 6. In this embodiment, the groove of the inclined element 5 is The depth and the groove depth of the axial element 6 are the same.

  FIG. 3 is a developed view of the left half of the tread portion 2 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 description thereof is omitted. As shown in FIG. 3, the tread portion 2 of this embodiment is provided with an inner lateral groove 12 having one end connected to the axial element 6 and extending inward in the tire axial direction. Such inner lateral grooves 12 enhance drainage performance.

  The other end of the inner lateral groove 12 terminates without communicating with other grooves. Thereby, since the fall of the rigidity of the crown land part 4B to which a big ground pressure acts is suppressed, the fall of steering stability performance is suppressed. In this embodiment, since the inner lateral groove 12 terminates without reaching the tire equator C, the above-described action is effectively exhibited.

  Although not particularly limited, the groove width W1 of the inner lateral groove 12 is preferably about 80% to 125% of the maximum width Wb of the axial element 6. The groove depth of the inner lateral groove 12 is desirably about 80% to 125% of the groove depth of the main groove 3. Furthermore, the length Lc of the inner lateral groove 12 in the tire axial direction is desirably 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. Such an axial element 6 can further store more water. In the present specification, the inner portion 10b in which the width W2 gradually increases will be referred to as a gradually increasing portion 13 hereinafter.

  Furthermore, in this embodiment, the corner portion 11B of the crown land portion 4B is provided with a chamfered portion 14 including a slope 14a that descends toward the main groove 3. Such a chamfered portion 14 increases the water holding capacity 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 can be improved in a balanced manner. In the present embodiment, the chamfered portion 14 is formed in a triangular shape in plan view.

  Moreover, in this embodiment, the outer side lateral groove | channel 16 which one end is continued to the axial direction element 6 and extends in the tire axial direction outer side is provided. Thereby, drainage performance improves. In the present embodiment, the outer lateral groove 16 continues to the tread end Te.

  It is desirable that the depth (not shown) of the outer lateral groove 16 is smaller than the depth of the main groove 3. Thereby, since the rigidity fall of 4 A of shoulder land parts is suppressed, steering stability performance is maintained highly. Further, since a step-shaped groove bottom (not shown) is formed between the outer lateral groove 16 and the axial element 6, this step-shaped groove bottom suppresses the reduction of the water retaining effect of the axial element 6. To do.

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

  FIG. 3 shows a pattern including all of the inner lateral grooves 12, the gradually increasing portions 13, the chamfered portions 14, and the outer lateral grooves 16. However, the present invention is not limited to such an embodiment. The present invention may be a pattern in which any one of the inner lateral groove 12, the gradually increasing portion 13, the chamfered portion 14, and the outer lateral groove 16 or a plurality selected from these is added to the basic pattern of FIG.

  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 description thereof is omitted. As shown in FIG. 4, in this embodiment, the inclined element 5 </ b> A is formed in an arc shape that is convex toward one side in the tire axial direction, for example, toward the tire equator C side. Such an inclined element 5A has a larger groove volume than the inclined element 5 extending linearly, and therefore can store a large amount of water, thus improving drainage performance.

  In the inclined element 5A of the present embodiment, the angle α1 with respect to the tire axial direction gradually decreases from the first arrival side to the rear arrival side in the rotation direction R. Such an inclination element 5A decreases the speed of the water flowing through the inside toward the rear arrival side in the rotation direction R, so that the holding of the water in the axial element 6 is further facilitated. Therefore, the tire 1 of this embodiment has excellent drainage performance.

  As mentioned above, although embodiment of this invention was explained in full detail, it cannot be overemphasized that this invention is not limited to exemplary embodiment, and can be deform | transformed and implemented in a various aspect.

A pneumatic tire of size 245 / 40R18 having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1, and the steering stability performance and drainage performance of each sample tire were tested. The main common specifications and test methods for each sample tire are as follows.
Groove depth of main groove (inclined element and axial element): 6mm
Maximum width of the inclined element Wa: 10 mm (3.2% of the tread width)
Tilting element angle θ1: 80 °
“Parallel to the rear-side groove wall” in Table 1 means that the groove edge of the first-side groove wall extends parallel to the groove edge of the rear-side groove wall. Meaning that the groove edge of the wall is inclined toward the rear arrival side of the rotational direction R toward the tire equator C side The numerical value “α1” in Table 1 indicates that the first arrival side of the rotational direction toward the tire equator side is “positive”. It is indicated as “negative” on the arrival side in the same rotation direction.
The groove volumes of the axial elements of Examples 1, 10, and 11 are equal.

<Steering stability performance>
Each sample tire was mounted on all wheels of a four-wheel drive vehicle for racing with a displacement of 2000 cc under the following conditions. Then, the test driver drove the test course on the dry asphalt road surface, and the steering stability performance including steering response, rigidity, grip and the like at this time was evaluated by sensory evaluation. The results are displayed with a score of Comparative Example 1 being 100. The larger the value, the better.
Rim: 18 × 8.5J
Internal pressure: 200kPa

<Drainage performance>
The lateral acceleration (lateral G) acting on the front wheels when running on a test course on an asphalt road surface with a radius of 100 m provided with a puddle with a water depth of 2 mm was measured using the above vehicle. The result is displayed as an index with the value of Comparative Example 1 as 100, using an average lateral G (lateral hydroplaning test) when the vehicle speed is 50 to 80 km / h. The larger the value, the better.
Table 1 shows the test results.

  As a result of the test, it was confirmed that the drainage performance of the tire of the example was improved while the deterioration of the steering stability performance was suppressed compared to the tire of the comparative example.

DESCRIPTION OF SYMBOLS 1 Tire 2 Tread part 3 Main groove 5 Inclination element 6 Axial element 8a Groove wall R Rotation direction Wa Maximum width Wb of inclination element Maximum width of axial element

Claims (9)

A tire having a tread portion in which a rotation direction is specified,
The tread portion is provided with at least one main groove extending continuously in a zigzag shape in the tire circumferential direction at a position away from the tire equator,
The main groove includes inclined elements and axial elements alternately in the tire circumferential direction,
The inclined element extends inclined toward the outer side in the tire axial direction toward the rear arrival side in the rotational direction,
The axial direction element is arranged such that a groove wall located on an outer portion in the tire axial direction and on the rear arrival side in the rotational direction scrapes off water in front of the tread during running of the tire in the rotational direction in the rotational direction. Extending in the tire axial direction from the side,
The maximum width of the axial element is formed to be greater than the maximum width of the inclined element;
tire.   The tire according to claim 1, wherein the axial element extends at an angle of 10 ° or less with respect to the tire axial direction.   2. The tire according to claim 1, wherein the axial element extends at 0 ° with respect to the tire axial direction, or is inclined toward the first arrival side in the rotational direction toward the tire equator side.   The tire according to any one of claims 1 to 3, wherein a width of an inner portion in the tire axial direction of the axial element gradually increases toward an inner side in the tire axial direction.   The tire according to any one of claims 1 to 4, wherein the tread portion is provided with an inner lateral groove having one end connected to the axial element and extending inward in the tire axial direction.   The tire according to claim 5, wherein the other end of the inner lateral groove terminates without communicating with another groove. The tread portion has a land portion on the inner side in the tire axial direction of the main groove,
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,
The tire according to any one of claims 1 to 6, wherein the corner portion is provided with a chamfered portion including an inclined surface descending toward the main groove.   The tire according to any one of claims 1 to 7, wherein the tread portion is provided with an outer lateral groove having one end connected to the axial element and extending outward 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.

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