JP2012076656A - Agricultural tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve traction performance of an agricultural tire on a farmland while suppressing vibration thereof on a pavement.SOLUTION: The agricultural tire includes: a plurality of lug blocks 12 provided on a tread 16; and a flat part 14 or a recessed part 15 (a specific curvature region) provided at least on either one of a groove bottom between the lug blocks 12 circumferentially adjacent to each other in the tire and a wall part 12B on the side of a stepping-on end 12A of each of the lug blocks 12. Soil enters between the lug blocks 12 circumferentially adjacent to each other in the tire during traveling on farmland. However, at that time, each rib 14 (the specific curvature region) prevents the soil from flowing breadthwise in the tire. Therefore, it increases soil pressure on the side of the stepping-on end 12A of each of the lug blocks 12. Accordingly, even if the inclination angle of each of the lug blocks 12 with respect to the tire is relatively increased breadthwise, soil is sufficiently compacted between the lug blocks 12 so as to improve the shear strength of the soil.

Description

  The present invention relates to an agricultural tire.

  A traveling body with a lug having a plurality of lugs extending obliquely with respect to the tire circumferential direction from the tread center portion of the tread portion toward the tread shoulder portion, wherein the shoulder end portion is closer to the tire rotation direction than the center end portion. A structure for grounding first is disclosed (see Patent Document 1).

JP 2008-24271 A

  In recent years, the use of agricultural tires on paved roads as well as farmland has increased. The reason for this is the need to move between distant farmlands due to the consolidation of farm management. On the other hand, this means that there has been a strong demand for improved performance such as vibration and wear, which has not been relatively important in conventional agricultural tires. Therefore, there is a tendency to demand a high-angle pattern having a large inclination angle, which is advantageous for reducing vibration, instead of a low-angle pattern having a small inclination angle of the lug block with respect to the tire width direction conventionally used.

  However, the high-angle pattern greatly reduces the traction performance on rough terrain that is most needed for agricultural tires. One of the major causes is that in the case of a high-angle pattern, the soil grasped by the lug block tends to flow in the tire width direction.

  In general, the soil has a higher shear strength, and the rug block can generate traction by scratching the compacted soil. The fact that this soil tends to flow in the tire width direction means that the soil under the tread surface cannot be sufficiently compacted, and as a result, the traction performance is lowered without fully utilizing the shear strength of the soil. In other words, in order to improve traction performance with a high-angle lug block, it is important how to suppress the flow of soil under the tread surface.

Sea urchin

  In view of the above facts, an object of the present invention is to improve traction performance on agricultural land while suppressing vibration on a paved road in agricultural tires.

  According to the first aspect of the present invention, at least one of the plurality of lug blocks provided on the tread, the groove bottom between the lug blocks adjacent to each other in the tire circumferential direction, and the wall portion on the stepping end side of the lug block is provided on the farmland. And a specific curvature region that suppresses the soil between the lug blocks from flowing to the outside in the tire width direction when traveling at a vehicle.

  In the agricultural tire according to claim 1, the soil enters between the lug blocks adjacent to each other in the tire circumferential direction when traveling on the farmland. At this time, the soil may flow in the tire width direction due to the specific curvature region. Since it is suppressed, the pressure of the soil at the stepped-in end side of the lug block increases. Therefore, even if the inclination angle of the lug block with respect to the tire width direction is relatively large, the soil can be sufficiently compacted between the lug blocks and the shear strength of the soil can be improved. For this reason, it is possible to ensure the traction performance on the farmland while suppressing the vibration on the paved road.

  According to a second aspect of the present invention, in the agricultural tire according to the first aspect, the singular curvature region is formed near the stepping end, and the tire is 5 to 75% of the interval between the lug blocks adjacent in the tire circumferential direction. It is the flat part or recessed part which has the circumferential direction length.

  Here, the lower limit of the ratio of the length in the tire circumferential direction of the flat portion or the concave portion with respect to the gap between the lug blocks is set to 5%. If the lower limit is not reached, a sufficient pressure increase cannot be obtained on the stepping end side of the lug block. Because. Moreover, the upper limit is set to 75% because if it exceeds this, the pressure of the soil on the kicking end side of the lug block increases, leading to an increase in running resistance.

  In the agricultural tire according to claim 2, the flow of soil in the tire width direction is directly suppressed by a flat portion or a recess having an appropriate tire circumferential direction length formed near the stepped end of the lug block. The traction performance on farmland can be further improved.

  According to a third aspect of the invention, in the agricultural tire according to the first or second aspect, the singular curvature region occupies a region of 10% or more of the total area of the groove bottom and the wall portion, and the groove An uneven portion having a height difference of 10% or less of the height of the lug block with respect to the bottom is provided.

  Here, the reason why the unevenness portion occupies 10% or more of the total area of the groove bottom and the wall portion is that if it is less than this, the effect of suppressing the flow of soil becomes insufficient. In addition, the difference in height of the concavo-convex portion is set to 10% or less of the height of the lug block, if it exceeds this, it is difficult to realize by simple surface processing, and there is no cost advantage in mold production or the like. .

In the agricultural tire according to claim 3, the soil traction in the tire width direction is suppressed by an uneven portion having an appropriate size that can be formed by surface processing, and the traction on the farmland is increased without increasing the amount of rubber. Performance can be improved.
According to a fourth aspect of the present invention, in the agricultural tire according to the third aspect, the concavo-convex portion is formed continuously in the tire circumferential direction.

  In the agricultural tire according to claim 4, since the uneven portions are continuous in the tire circumferential direction, the flow of soil in the tire width direction can be further suppressed.

  As described above, according to the agricultural tire according to claim 1 of the present invention, in the agricultural tire, it is possible to improve the traction performance on the farmland while suppressing the vibration on the paved road. Excellent effect is obtained.

  According to the agricultural tire of the second aspect, it is possible to obtain an excellent effect that the soil flow in the tire width direction can be directly suppressed and the traction performance on the farmland can be further improved.

  According to the agricultural tire of the third aspect, an excellent effect is obtained that the traction performance on the farmland can be improved without increasing the amount of rubber.

  According to the agricultural tire of the fourth aspect, an excellent effect is obtained that the flow of soil in the tire width direction can be further suppressed.

FIGS. 1 to 5 relate to the first embodiment, and FIG. 1 is a plan view of a main part showing an example of a tread pattern in an agricultural tire. It is 2-2 arrow sectional drawing in FIG. 1 which shows a flat part. FIG. 3 is a cross-sectional view taken along arrow 3-3 in FIG. 1 showing a recess. It is a principal part top view which shows an example of the tread pattern in the tire for agriculture. FIG. 5 is a sectional view taken along arrow 5-5 in FIG. 6 and 7 relate to the second embodiment, and FIG. 6 is a plan view showing an example of a tread pattern in an agricultural tire. It is a perspective view which shows the uneven | corrugated | grooved part formed from the wall part by the side of the depression end of a lug block to the groove bottom.

[First Embodiment]
In FIG. 1, the agricultural tire 10 according to the present embodiment has a plurality of lug blocks 12 and a flat portion 14 (FIG. 2) or a concave portion 15 (FIG. 3) as an example of a specific curvature region.

  The plurality of lug blocks 12 are provided on the tread 16, and are alternately arranged on both sides in the tire width direction, for example, in the tire circumferential direction (see FIG. 6). Each lug block 12 is inclined forward in the tire rotation direction (arrow F direction) with respect to the tire width direction.

  A groove bottom 18 that forms a valley is formed between the lug blocks 12 adjacent to each other in the tire circumferential direction, and the width dimension of the lug block 12 gradually decreases from the groove bottom 18 side toward the outer side in the tire radial direction, for example. ing. That is, the width dimension W2 of the lug block 12 at the outer end in the tire radial direction is smaller than the width dimension W1 of the lug block 12 at the groove bottom 18. In other words, the wall portion 12B on the step-in end 12A side of the lug block 12 is formed in a skirt shape on the front side in the tire rotation direction (arrow F direction) toward the inner side in the tire radial direction. Further, the wall portion 12D on the side of the kicking end 12C in the lug block 12 is formed in a skirt shape on the rear side in the tire rotation direction (arrow R direction) side toward the inner side in the tire radial direction.

  The end 12E on the center side in the tire width direction of the lug block 12 is arranged so as to partially overlap the end portion 12E on the center side in the tire width direction of the other lug block 12 in the tire circumferential direction. Thereby, the vibration at the time of pavement running can be reduced.

  Next, in FIGS. 1 and 2, the flat portion 14 is provided, for example, on at least one of the groove bottom 18 between the lug blocks 12 adjacent to each other in the tire circumferential direction and the wall portion 12B on the stepping end 12A side of the lug block 12. It is a specific curvature region that suppresses the soil between the lug blocks 12 from flowing outward in the tire width direction when traveling on farmland.

  In FIG. 1, the flat portion 14 is formed, for example, near the stepping end 12 </ b> A of the groove bottom 18, and has a tire circumferential direction length L <b> 1 that is 5 to 75% of an interval L between adjacent lug blocks 12 in the tire circumferential direction. Yes. In the present embodiment, the flat portion 14 extends from the lower end of the wall portion 12B on the stepping end 12A side of the lug block 12 to the front side in the tire rotation direction (arrow F direction). The flat portion 14 is formed at a position away from the lug block 12, formed only on the wall portion 12 </ b> B on the stepping end 12 </ b> A side of the lug block 12, or formed from the wall portion 12 </ b> B to the groove bottom 18. Also good.

  Here, the lower limit of the ratio of the tire circumferential direction length L1 of the flat portion 14 to the interval L between the lug blocks 12 is set to 5%. If the lower limit is less than this, the pressure rises sufficiently on the stepping end 12A side of the lug block 12 It is because it cannot be obtained. Further, the upper limit is set to 75% because if the upper limit is exceeded, the pressure of the soil on the side of the kicking end 12C of the lug block 12 increases, resulting in an increase in running resistance. The interval L between the lug blocks 12 is a tire circumferential direction distance between the kicking end 12C of one lug block 12 and the stepping end 12A of the other lug block 12 at the tread end T.

  Here, the tread end T means that an agricultural tire 10 is mounted on a standard rim defined in the 2010 edition YEAR BOOK issued by JATMA (Japan Automobile Tire Association), and the applicable size / ply in the YEAR BOOK Fills 100% of the air pressure (maximum air pressure) corresponding to the maximum load in the rating as the internal pressure, and indicates the outermost contact portion in the tire width direction when the maximum load is applied. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

  In the example shown in FIG. 1, only one flat portion 14 is formed at a position close to the tread end T side between adjacent lug blocks 12. Moreover, in the example shown by FIG. 4, FIG. 5, while the recessed part 15 is set comparatively narrowly, it spaced apart in the tire width direction between the adjacent lug blocks 12, and is formed in two places. . In this case, the tire circumferential direction length L1 of each recess 15 may be constant, or may be appropriately changed within the range of the ratio to the interval L of the lug block 12 described above. The width of the recess 15 can also be set arbitrarily.

  The configuration of the flat portion 14 is also applied to the concave portion 15 in FIG. The concave portion 15 is also a specific curvature region, but is set to have a larger curvature (a smaller radius of curvature) than the flat portion 14 (FIG. 2) in the cross section in the tire width direction.

(Function)
This embodiment is configured as described above, and the operation thereof will be described below. In FIG. 1 to FIG. 3, in the agricultural tire 10 according to the present embodiment, soil enters between the lug blocks 12 adjacent to each other in the tire circumferential direction when traveling on the farmland. Since the soil or the recess 15 prevents the soil from flowing in the tire width direction, the pressure of the soil on the stepping end 12A side of the lug block 12 increases. Therefore, even if the inclination angle of the lug block 12 with respect to the tire width direction is relatively large, the soil can be sufficiently compacted between the lug blocks 12 and the shear strength of the soil can be improved. For this reason, it is possible to ensure the traction performance on the farmland while suppressing the vibration on the paved road. In particular, since the flat portion 14 or the concave portion 15 is formed near the stepping end 12A of the lug block 12 and has an appropriate tire circumferential direction length, the flow of soil in the tire width direction is directly suppressed. Thus, the traction performance on the farmland can be further improved.

[Second Embodiment]
6 and 7, in the agricultural tire 20 according to the present embodiment, the specific curvature region occupies a region of 10% or more of the total area of the groove bottom 18 and the wall portion 12B, and the groove bottom 18 is used as a reference. The rugged block 24 having a height difference of 10% or less of the height H of the lug block 12 is provided.

  Here, the reason why the unevenness portion 24 occupies 10% or more of the total area of the groove bottom 18 and the wall portion 12B is that if it is less than this, the effect of suppressing the flow of soil becomes insufficient. Moreover, if the height difference of the concavo-convex portion 24 is set to 10% or less of the height H of the lug block 12, if it exceeds this, it is difficult to realize by simple surface processing, and there is no cost advantage in mold production or the like. Because. Here, the “total area” refers to a total sum of the areas of the groove bottom 18 and the wall portion 12 </ b> B in the tread plan view when the tread 16 is developed in a planar shape.

  The concavo-convex portion 24 is formed in, for example, a corrugated cross section, and is formed continuously from the wall portion 12B on the stepping end 12A side of the lug block 12 to the groove bottom 18 in the tire circumferential direction. As shown in FIG. 6, the uneven portion 24 is not formed on the wall portion 12 </ b> D on the side of the kicking end 12 </ b> C of the lug block 12. This is because if the soil flow toward the outer side in the tire width direction is suppressed in the wall portion 12D on the side of the kick-out end 12C, the pressure of the soil on the side of the kick-out end 12C increases, leading to an increase in running resistance.

  In addition, the uneven | corrugated | grooved part 24 is not restricted to what continues in a tire circumferential direction, The thing arrange | positioned intermittently in a tire circumferential direction may be sufficient. The cross-sectional shape of the concavo-convex portion 24 is not limited to an arcuate waveform as shown in the figure, and may be a rectangular or trapezoidal waveform.

  Since other parts are the same as those in the first embodiment, the same parts are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

(Function)
This embodiment is configured as described above, and the operation thereof will be described below. 6 and 7, in the agricultural tire 20 according to the present embodiment, the uneven flow portion 24 of an appropriate size that can be formed by surface processing allows the flow of soil in the tire width direction without increasing the amount of rubber. It can suppress and can improve the traction performance in farmland. Since the uneven portion 24 is continuous in the tire circumferential direction, the flow of soil in the tire width direction can be further suppressed.

  It is also possible to combine the first embodiment and the second embodiment described above. In this case, the total area of the groove bottom 18 and the wall portion 12B, which is the basis of the area ratio for forming the uneven portion 24 (FIG. 6), excludes the region occupied by the flat portion 14 or the recessed portion 15 (FIGS. 1 to 3). Is calculated.

  In FIG. 6, two pairs of lug blocks 12 are drawn on both sides of the tire equatorial plane CL. The lug blocks 12 are formed on the entire circumference of the tire. The lug block 12 in FIG. 1 and the flat part 14 or the recessed part 15 are also formed in the whole tire periphery.

  Moreover, although the flat part 14, the recessed part 15, and the uneven | corrugated | grooved part 24 were mentioned as an example of a peculiar curvature area | region, a peculiar curvature area | region is not restricted to these, As long as the flow of the soil to a tire width direction can be suppressed. Any shape region may be used.

  Here, the “singular curvature region” refers to the original contour (solid line and broken line) of the groove bottom 18 and the original contour (not shown) of the wall portion 12B on the stepping end 12A side of the lug block 12. It means a region with a clearly different curvature.

  Specifically, as shown in FIG. 2, the contour of the groove bottom 18 gradually falls to the inner side in the tire radial direction from the tire equatorial plane CL side toward the outer side in the tire width direction. In the flat part 14 and the recessed part 15 which concern on, there is no such depression. The flat portion 14 and the concave portion 15 can be regarded as the groove bottom 18 partially raised. As shown in FIG. 1, the groove bottom 18 and the wall portion 12 </ b> B are originally formed as smooth surfaces without irregularities, but the irregularities 24 according to the second embodiment are not literally smooth surfaces. Thus, the flat part 14, the recessed part 15, and the uneven | corrugated | grooved part 24 are area | regions which have a curvature obviously different from the original outline of the site | part in which each is formed.

(Test example)
The traction force was compared as a traction performance test for the conventional example of the specification shown in Table 1 and the tires according to Examples 1 to 3. The test conditions are as follows.
Tire size: AGR 710 / 70R42
Internal pressure: 160 kPa
Load acting on one tire: 55kN (5600kgf)
Road surface: grassland and arable land

  The traction force in Table 1 is indicated by an index in which the traction force of the conventional example in the grassland and the traction force of the conventional example in the cultivated land are each 100, and the larger the value, the better the result. According to this result, it was found that Examples 1 to 3 exceeded the conventional example in both grassland and arable land, and had good traction performance.

DESCRIPTION OF SYMBOLS 10 Agricultural tire 12 Lug block 12A Depression end 12B Wall part 14 Flat part (singular curvature area)
15 Concavity (singular curvature region)
16 Tread 18 Groove bottom 20 Agricultural tire 24 Concavity and convexity (singular curvature region)
CL tire equator plane L interval between adjacent lug blocks L1 tire circumferential direction length of flow suppressing means

Claims (4)

A plurality of lug blocks provided in the tread;
At least one of the groove bottom between the lug blocks adjacent to each other in the tire circumferential direction and the wall portion on the stepping end side of the lug block flows the soil between the lug blocks outward in the tire width direction when traveling on farmland. A singular curvature region that suppresses this,
Agricultural tire having.   The said specific curvature area | region is a flat part or recessed part which is formed near the said depression end, and has the tire circumferential direction length of 5 to 75% of the space | interval of the said lug block adjacent to a tire circumferential direction. Agricultural tire.   The uneven portion occupies a region of 10% or more of the total area of the groove bottom and the wall as the specific curvature region and has a height difference of 10% or less of the height of the lug block with respect to the groove bottom. Agricultural tire according to claim 1 or 2, comprising:   The agricultural tire according to claim 3, wherein the uneven portion is formed continuously in the tire circumferential direction.