JP2011246053A - Tire for atv - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain traction performance and sliding performance.SOLUTION: A zigzag sipe extending in a direction which forms an angle θ of 10 degrees or less to a tire circumferential direction is formed in a block. Amplitude W of the zigzag sipe formed in the block arranged on a tire equatorial plane or a position nearest to the tire equatorial plane is set to be larger than the amplitude W of the zigzag sipe formed on the block disposed nearest to a tread end-side.

Description

  The present invention relates to an ATV tire having both traction and sliding properties.

  ATV (ALL TERRAIN VEHICLE) is intended for driving on rough roads such as sand and muddy land, and is sometimes called an all-terrain vehicle or a buggy. This ATV has one or two steering wheels provided at the front part of the vehicle body and left and right drive wheels provided at the rear part of the vehicle body. A differential device such as a passenger car is interposed in the drive wheels. Not. Therefore, the left and right drive wheels always rotate at the same rotational speed, and therefore, the drive wheels must be slid in the lateral direction when turning.

  On the other hand, in the tire for ATV, a block pattern is adopted in the tread portion in order to sufficiently secure a grip force on a rough road. However, although the block pattern has a higher traction force to move forward by biting into the road surface, it tends to be inferior in turning performance because it is difficult to slide laterally during turning.

  Therefore, in the past, a large-sized block was formed in the region on the tire equatorial plane side (crown region), which has a strong influence on traction, and the traction was improved by increasing the block rigidity, while improving the slidability. A small-sized block is formed in the region on the tread end side (shoulder region) where the influence is strong, and the sliding property is improved by lowering the block rigidity.

  However, in the conventional method in which the block size is different between the crown region and the shoulder region, since the strength also varies with the block size, the block is easily damaged in the shoulder region, resulting in a decrease in tire durability. . Moreover, the problem that the designability and the freedom degree of a tire design are reduced also arises.

  In Patent Document 1 below, it is proposed that a chamfered tapered surface is provided at a corner portion on the outer side in the tire axial direction of a block provided at a predetermined position to improve slidability by reducing the catching on the road surface. Yes. However, this method has a limit in improving the slidability and has not yet obtained a satisfactory result.

JP 2002-362113 A

  Therefore, the present invention is based on the fact that the block is provided with siping extending zigzag in the tire circumferential direction, and the zigzag amplitude W is large in the block on the tire equatorial plane side and small in the block on the tread end side. An object of the present invention is to provide an ATV tire that can improve sliding performance without greatly different block sizes between the tire equatorial plane side and the tread end side and ensuring high traction.

In order to solve the above problems, the invention of claim 1 of the present application is an ATV tire in which a plurality of blocks are provided in a tread portion,
In the block, a zigzag siping extending in a direction where the angle θ with respect to the tire circumferential direction is within 10 ° is formed,
The amplitude W of the zigzag siping formed in the block arranged on the tire equator plane or the position closest to the tire equatorial plane is the zigzag siping amplitude formed in the block arranged closest to the tread end. It is characterized by being set larger than the amplitude W.

  According to a second aspect of the present invention, the zigzag siping is a rectangular wave siping in which a zigzag element forms a rectangular shape.

According to a third aspect of the present invention, the block has a center of gravity of a block area in a crown region between the tire equator plane and a first boundary line separated from the tire equator plane by a distance L1 of 1/6 of the tread width TW. A middle block having a center of gravity of the area of the block in a middle region between the first boundary line and a second boundary line separated from the tire equator by a distance L2 of 2/6 of the tread width TW. And a shoulder block having an area center of gravity of the block in a shoulder region between the second boundary line and the tread end, and
An amplitude Wc of the rectangular wave-shaped siping formed in the crown block, an amplitude Wm of the rectangular wave-shaped siping formed in the middle block, and an amplitude Ws of the rectangular wave-shaped siping formed in the shoulder block,
Wc>Wm> Ws
It is characterized by that.

In the invention of claim 4, the length direction pitch Pc of the rectangular wave-shaped siping formed on the crown block and the length direction pitch Pm of the rectangular wave-shaped siping formed on the middle block are 10 respectively. The pitch Ps in the longitudinal direction of the rectangular wave-shaped siping formed in the shoulder block is in the range of 6-8 mm; and
Pc ≧ Pm> Ps
It is characterized by that.

  In the invention of claim 5, the ratio Am / Ac of the area Ac of the tread of the crown block to the area Am of the tread of the middle block is in the range of 0.8 to 0.9, and the tread of the crown block is A ratio As / Ac of the area Ac of the surface and the area As of the tread surface of the shoulder block is in the range of 0.7 to 0.8.

  According to a sixth aspect of the present invention, the middle block and the shoulder block are formed of a trapezoidal block having a block side edge on the outer side in the tire axial direction as an upper base and a block side edge on the inner side in the tire axial direction as a lower bottom. Yes.

  According to a seventh aspect of the present invention, both ends of the rectangular wave-shaped siping formed in the shoulder block in the longitudinal direction are located on the tread end side with respect to the zigzag center line of the rectangular wave.

  As described above, the present invention forms siping extending in the tire circumferential direction or at an angle close to the block, as described above. Therefore, the block pieces that are subdivided in the tire axial direction by the siping are easily deformed in the tire axial direction, and can be deformed during turning to easily slide the tire. The siping has a zigzag shape. Therefore, the adjacent block pieces are integrated in the tire circumferential direction when the zigzag portions engage with each other, and the circumferential rigidity of the block is reduced little and maintained high. Accordingly, excellent traction can be exhibited.

  Moreover, the amplitude W of the zigzag siping is set to be large for the block arranged on the tire equatorial plane side and small for the block arranged on the tread end side.

  Here, the larger the amplitude W, the more firmly the block pieces mesh with each other, so that the circumferential rigidity of the block increases. Therefore, by increasing the simpling amplitude W in the block on the tire equatorial plane side having a strong influence on the traction, the traction can be improved more effectively. Further, the smaller the amplitude W, the weaker the engagement between the block pieces, so that not only the tire axial rigidity but also the circumferential rigidity is reduced, so that the entire block rigidity is lowered. Therefore, by reducing the simpling amplitude W in the block on the tread end side having a strong influence on the slidability, the slidability and further the slide controllability can be improved more effectively.

FIG. 2 is a development view showing a tread pattern of the tire for ATV of the present invention developed on a plane. It is a top view which expands and shows a crown block. It is a top view which expands and shows a middle block. It is a top view which expands and shows a shoulder block. It is sectional drawing of the block which shows the effect by siping.

Hereinafter, embodiments of the present invention will be described in detail.
In FIG. 1, the ATV tire 1 of the present embodiment includes a block pattern in which a plurality of blocks 3 are spaced apart on a tread portion 2.

  In this example, the block 3 includes a crown block 3C having a block area centroid g in the crown area Qc, a middle block 3M having a block area centroid g in the middle area Qm, and a block area centroid g in the shoulder area Qs. And a shoulder block 3S. The “area centroid g” means the area centroid g on the tread surface of each block 3.

  The crown region Qc is defined as a region between the tire equator plane C and a first boundary line J1 that is separated from the tire equator plane C by a distance L1 that is 1/6 of the tread width TW. The middle region Qm is defined as a region between the first boundary line J1 and the second boundary line J2 separated from the tire equator plane C by a distance L2 of 2/6 of the tread width TW. . The shoulder region Qs is defined as a region between the second boundary line J2 and the tread end Te. The “tread end Te” means a tire circumferential line passing through the outermost point in the tire axial direction on the tread surface in the block 3 arranged on the outermost side in the tire axial direction. The “tread width TW” means a distance in the tire axial direction along the contour of the tread surface of the tread portion 2 between the tread ends Te and Te. The distances L1 and L2 also mean the distance in the tire axial direction along the contour line of the tread surface of the tread portion 2.

  Also, the block where the area centroid g is located on the tire equator plane C is included in the crown block 3C, and the block where the area centroid g is located on the first boundary line J1 is included in the middle block 3M. In addition, a block in which the area gravity center g is located on the second boundary line J2 is included in the shoulder block 3S.

  Each block 3 is formed with a zigzag siping 5 extending in a direction having an angle θ of 10 ° or less with respect to the tire circumferential direction. That is, the zigzag center line i in the siping 5 is arranged at an angle θ of 10 ° or less with respect to the tire circumferential direction. In this example, the most preferable case where the angle θ is 0 ° is shown.

  Next, the crown block 3C has a substantially rectangular main body 5 as specifically shown in FIG. 2, and in this example, in order to further improve the traction, the tire rotation direction A V-shaped dent 6 is formed at the end of the rear landing side, and a V-shaped overhang 7 is formed at the end of the tire rotation direction first landing side. Therefore, the block side edges Ye on both sides in the tire circumferential direction of the block 3C are inclined from the central part of the block side edges Ye toward the rear arrival side in the tire rotation direction. The angle α of the block side edge Ye in the tire circumferential direction with respect to the tire axial direction is preferably about 5 to 10 °. However, if necessary, the crown block 3C can be formed in a rectangular shape without providing the recess 6 and the overhang 7.

  The crown block 3C is formed with two sipings 5C in this example. As this siping 5C, for example, a triangular wave-shaped siping in which the zigzag elements are triangular may be adopted, but in order to more firmly engage the zigzag portions, a rectangular wave siping 10C in which the zigzag elements form a rectangular shape is most preferable. Adopted. For the same purpose, the number of zigzag pitches is at least larger than 1, preferably 2 or more.

  The crown block 3C formed in this way is subdivided into three block pieces 11 in the tire axial direction by two sipings 5C in this example. Since the block pieces 11 are not restrained in the tire axial direction, they are easily deformed in the tire axial direction as shown exaggeratedly in FIG. Accordingly, the tire can be easily slid by being deformed during turning. In contrast, since the zigzag portions mesh with each other in the tire circumferential direction, the block pieces 11 are integrally connected in the tire circumferential direction. Therefore, the circumferential rigidity of the block 3C is maintained high, and excellent traction properties can be exhibited.

  Next, the middle block 3M and the shoulder block 3S, specifically, as shown in enlarged views in FIGS. 3 and 4, the block side edge Xeo on the outer side in the tire axial direction is the upper bottom, and the block side on the inner side in the tire axial direction. It is formed from a trapezoidal block 12 with the edge Xei as the bottom. Accordingly, the block side edges Ye and Ye on both sides in the tire circumferential direction can be inclined toward each other toward the outer side in the tire axial direction, and as a result, the initial sliding out of the tire can be improved. In other words, the sliding of the tire from the straight traveling state becomes smooth, the slidability is improved, and the turning performance can be improved. Note that if the angle β of the block side edge Ye with respect to the tire axial direction is too small, slippage is not improved, and conversely if it is too large, the traction is adversely affected. Therefore, the angle β is preferably in the range of 5 to 10 °.

  Further, sipings 5M and 5S are also formed in the middle block 3M and the shoulder block 3S, similarly to the crown block 3C. The sipings 5M and 5S are also the same as the siping 5C, and rectangular wave sipings 10M and 10S in which zigzag elements form a rectangular shape are employed in order to more firmly engage the zigzag portions.

  At this time, the amplitude W of the siping 5 formed on the block 3 arranged on the tire equator plane C or the position closest to the tire equator plane C is formed on the block 3 arranged closest to the tread end Te. It is set larger than the amplitude W of the siping 5. In the case of this example, the amplitude Wc of the rectangular wave-shaped siping 10C formed in the crown block 3C is set larger than the amplitude Ws of the rectangular wave-shaped siping 10S formed in the shoulder block 3S.

  Here, the greater the siping amplitude W, the more firmly the block pieces 11 mesh with each other, so that the circumferential rigidity of the block 3 is kept high. Therefore, by increasing the amplitude Wc of the rectangular wave-shaped siping 10C in the crown block 3C having the strongest influence on the traction, the traction can be further improved. On the other hand, the smaller the amplitude W, the weaker the engagement between the block pieces 11, so that not only the tire axial rigidity but also the circumferential rigidity is reduced, so that the entire block rigidity is lowered. Therefore, by reducing the amplitude Ws of the rectangular wave-shaped siping 10S in the shoulder block 3S having the strongest influence on the slidability, the slidability can be further improved while suppressing the influence on the traction.

  Particularly in this example, when the amplitude of the rectangular wave-shaped siping 10M formed in the middle block 3M is Wm, Wc> Wm> Ws is set. As a result, the balance between traction and slidability is optimized over the entire block pattern, and the traction and slidability can be more effectively exhibited as a whole tire.

  For the same purpose, when the pitch of the zigzag in the siping length direction of the rectangular wave siping 10C is Pc, the pitch of the zigzag of the rectangular wave siping 10M is Pm, and the pitch of the zigzag of the rectangular wave siping 10S is Ps, It is preferable that Pc ≧ Pm> Ps. In general, the greater the zigzag pitch P, the higher the rigidity of the zigzag element, so the overall rigidity of the block can be maintained high. Conversely, the smaller the zigzag pitch, the smaller the zigzag element rigidity, The rigidity of the entire block decreases. Therefore, by setting Pc ≧ Pm> Ps, it is advantageous for traction.

  The zigzag pitches Pc and Pm are preferably in the range of 10 to 12 mm, and the zigzag pitch Ps is preferably in the range of 6 to 8 mm. Even when the pitch P is large, if the balance with the amplitude W is poor, the zigzag element is easily deformed, and the above effect cannot be expected. Therefore, in the rectangular wave siping 10C, the ratio Wc / Pc is 0.25 to 0.4, in the rectangular wave siping 10M, the ratio Wm / Pm is 0.15 to 0.25, and in the rectangular wave siping 10S, the ratio Ws / Ps is 0. A range of 15 to 0.25 is preferred.

  When a plurality of sipings 5 (rectangular wave sipings 10) are provided in the block 3 as in this example, the distance Li between the zigzag center lines i and i is in the range of 20 to 40% of the tire axial width BW of the block 3. Is preferable. If it is 20% or less, the block pieces 11 between the sipings 5 (rectangular wave-shaped sipings 10) become too thin, resulting in insufficient strength. Conversely, if it exceeds 40%, the block pieces 11 on both sides become too thin, resulting in insufficient strength. .

  Moreover, it is preferable that both ends Ks in the length direction of the rectangular wave-shaped siping 10S formed in the shoulder block 3S are located on the tread end Te side with respect to the zigzag center line i of the rectangular wave. This is because the siping 5 starts to open from the end Ks, and the end Ks is located closer to the tread end Te than the zigzag center line i, so that the tire starts smoothly and slides. Improved. For the same purpose, also in the middle block 3M, both end portions Km in the length direction of the rectangular wave-shaped siping 10M are positioned on the tread end Te side with respect to the zigzag center line i. On the other hand, in the crown block 3C, both ends Kc in the length direction of the rectangular wave-shaped siping 10C are located on the tire equatorial plane C side with respect to the zigzag center line i in order to emphasize traction.

  As described above, the present invention is different from the conventional one in which the shoulder block is reduced in size to improve the slide performance. Therefore, as in this example, the ratio Am / Ac of the step surface area Ac of the crown block 3C to the step surface area Am of the middle block 3M is in the range of 0.8 to 0.9, and the crown block 3C The ratio As / Ac of the tread surface area Ac and the tread surface area As of the shoulder block 3S is in the range of 0.7 to 0.8. Therefore, the designability and the degree of freedom in tire design can be increased, uneven wear can be suppressed, and problems such as damage to specific blocks can also be solved.

  As for the height of the block 3, about 13 to 15 mm can be suitably employed as in the case of a conventional ATV tire, and the depth of the siping 5 is 75 to 90% of the height of the block 3. Is preferred.

  As described above, the particularly preferred embodiment of the present invention has been described in detail. However, the present invention is not limited to the illustrated embodiment, and the present invention is not limited to the illustrated embodiment. Needless to say, it is possible.

  A radial tire for ATV with a tire size of AT20 × 10R9 based on the block pattern shown in FIG. 1 was prototyped according to the specifications in Table 1, and the traction and sliding properties of each sample tire were tested and compared with each other. The tires were substantially the same except for the siping specifications.

For each tire:
(A) The ratio Am / Ac of the tread surface area Ac of the crown block to the tread surface area Am of the middle block is 0.8, the tread surface area Ac of the crown block, and the tread surface area As of the shoulder block The ratio As / Ac is 0.7,
(B) The block height of each block is 13 mm, and the depth of each siping is 75%,
(C) The angle α of the zigzag center line of each siping with respect to the tire circumferential direction is 0 °,
(D) The number of sipings formed in each block is two,
It was.

(1) Traction characteristics:
The tires were attached to all wheels of an ATV vehicle (sports-type four-wheel vehicle driven by a rear wheel of 660 cc) under the conditions of a rim (8.0 AT) and internal pressure (28 kPa), and ran on the ATV competition course. Then, the traction property at the time of starting 0 and the acceleration property during the running were evaluated by a five-point method in which the conventional example was set to four points by sensory evaluation of the driver. The greater the score, the better.

(2) Slide performance:
Driving on the ATV competition course, the tire slipping out from the straight running state at that time (initial sliding performance), the amount of sliding, and the controllability of the sliding were each given 4 points according to the sensory evaluation of the driver. The point method was used for evaluation. The greater the score, the better.

  In the evaluation, the point difference 0.1 is the minimum level at which the performance difference can be determined by simultaneous comparison, and the point difference 0.3 is the minimum level at which the performance difference can be determined without simultaneous comparison.

2 Tread 3 Block 3C Crown block 3M Middle block 3S Shoulder block 5, 5C, 5M, 5S Siping 10, 10C, 10M, 10S Rectangular wave-shaped siping C Tire equatorial plane i Zigzag center line J1 First boundary line J2 Second Boundary line Qc Crown area Qm Middle area Qs Shoulder area Te Tread edge

Claims (7)

A tire for ATV having a plurality of blocks in the tread portion,
In the block, a zigzag siping extending in a direction where the angle θ with respect to the tire circumferential direction is within 10 ° is formed,
The amplitude W of the zigzag siping formed in the block arranged on the tire equatorial plane or the position closest to the tire equatorial plane is the zigzag siping amplitude formed in the block arranged closest to the tread end. An ATV tire characterized by being set to be larger than the amplitude W.   2. The ATV tire according to claim 1, wherein the zigzag siping is rectangular wave siping in which a zigzag element forms a rectangular shape. The block includes a crown block having a center of gravity of a block in a crown region between a tire equatorial plane and a first boundary line separated from the tire equatorial plane by a distance L1 of 1/6 of the tread width TW. A middle block having a center of gravity of the area of the block in a middle region between the boundary line of the tire and a second boundary line separated from the tire equatorial plane by a distance L2 of 2/6 of the tread width TW, and the second boundary line And a shoulder block having a center of gravity of the area of the block in the shoulder region between the tread edge and the tread end,
An amplitude Wc of the rectangular wave-shaped siping formed in the crown block, an amplitude Wm of the rectangular wave-shaped siping formed in the middle block, and an amplitude Ws of the rectangular wave-shaped siping formed in the shoulder block,
Wc>Wm> Ws
The tire for ATVs according to claim 2 characterized by things. A pitch Pc in the length direction of the rectangular wave-shaped siping formed on the crown block and a pitch Pm in the length direction of the rectangular wave-shaped siping formed on the middle block are each in a range of 10 to 12 mm, and the shoulder The pitch Ps in the length direction of the rectangular wave-shaped siping formed in the block is in the range of 6 to 8 mm, and
Pc ≧ Pm> Ps
The ATV tire according to claim 3, wherein:   The ratio Am / Ac between the step surface area Ac of the crown block and the step surface area Am of the middle block is in the range of 0.8 to 0.9, and the step surface area Ac of the crown block and the shoulder block 5. The ATV tire according to claim 3, wherein the ratio As / Ac to the tread surface area As is in the range of 0.7 to 0.8.   6. The middle block and the shoulder block are each composed of a trapezoidal block having a block side edge on the outer side in the tire axial direction as an upper bottom and a block side edge on the inner side in the tire axial direction as a lower bottom. The tire for ATVs as described above.   The both ends of the longitudinal direction of the rectangular wave-shaped siping formed in the shoulder block are located on the tread end side with respect to the zigzag center line of the rectangular wave. ATV tires.

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