JP2008114756A - Tire for agricultural machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire for an agricultural machine improving vibration ride comfort, in particular, during traveling on good roads without deteriorating traction performance. <P>SOLUTION: A first vibration absorbing rubber 32 and a second vibration absorbing rubber 34 having a modulus lower than that of a tread rubber 24 are arranged respectively in a central region 40 and a side region 42 between a carcass 16 and a tread 22 of a tire 10 provided with a bead core 20, the carcass 16, the tread 22 provided on the radial outer side of the carcass 16 and a plurality of lugs 26 formed on the tread 22. This arrangement can improve vibration ride comfort without deteriorating traction performance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an agricultural machine tire having a plurality of lugs on a tread, and more particularly to an agricultural machine tire suitable for an agricultural vehicle that travels in a field such as a wetland, a soft ground, and a muddy land.

Conventionally, in agricultural machinery tires in which a plurality of lugs are formed in the shape of a square with a predetermined interval on the tread, the tread width is set as wide as possible to ensure the traction performance, which is the most basic performance. For example, it has been generally performed to set the tread width wider than the total tire width.
In such conventional agricultural machine tires, the traction performance and the vibration ride performance are basically in a trade-off relationship, and in order to ensure the predetermined traction performance, the vibration ride performance must be sacrificed. There was a problem.

Thus, various methods for improving the vibration ride comfort performance of such agricultural machine tires have been proposed and implemented (for example, Patent Document 1 and Patent Document 2).
For example, as a technique for improving the vibration ride comfort performance, it is known to form each lug so as to overlap with other lugs in the tire circumferential direction or the tire width direction.
JP 2006-224784 A JP 2004-299459 A

  By the way, in recent years, there are increasing opportunities for vehicles equipped with agricultural machinery tires to travel on good roads such as paved roads, so that the vibration riding comfort performance of agricultural machinery tires, which has not been noticed so much in the past, is attracting attention. It has become. As described above, methods for improving the vibration riding comfort performance of agricultural machinery tires have been proposed and realized. However, with these methods, the vibration riding comfort performance, which is in a trade-off relationship with traction performance, is achieved to a level that satisfies the user. There was a problem that it could not be improved.

  In recent years, agricultural machinery tires have been provided that improve the ride comfort of the vibration without substantially reducing the traction performance by making the total width of the tire and the tread width substantially the same. In the market, it has been strongly desired to provide tires for agricultural machinery with further improved vibration ride performance.

  Therefore, in view of the above facts, the present invention has an object to provide a tire for an agricultural machine in which vibration ride comfort performance, particularly vibration ride comfort performance when traveling on a good road, is improved without reducing traction performance. Yes.

  The inventor examined a method for maintaining and improving both the traction performance and the vibration riding comfort performance based on the fact that the traction performance and the vibration riding comfort performance described above are in a trade-off relationship. In general, a decrease in vibration ride performance of an agricultural vehicle (for example, an agricultural tractor, etc.) equipped with an agricultural machine tire is mainly caused by a pitch component based on a tread pattern (hereinafter referred to as a pattern pitch component). ing.

  In particular, when the agricultural machine tire is a bias tire, the distribution of the contact pressure on the tread surface is characterized by a W-shaped increase due to the contact pressure in the central section and the contact pressure in the side sections on both sides of the central section. The part where the contact pressure of the side section increases is specifically near the end of the tread surface, and if the tread pattern is a lag pattern, the outer side in the tire width direction of the lag on one side across the tire equatorial plane And the vicinity of the outer edge of the lug on the other side across the tire equatorial plane. Here, the inventor has paid attention to the fact that the pattern pitch component resulting from the W-shape causes vibration due to rolling of the agricultural machine tire, specifically, radial force variation (hereinafter referred to as RFV).

  Therefore, the agricultural machine tire according to claim 1 of the present invention is provided on a carcass extending in a toroidal shape between a pair of bead cores and on a radially outer side of the carcass, from a center part in a tire width direction toward a side part. A tread having a plurality of lugs extending obliquely in the tire circumferential direction, the tread comprising a central section and a side section continuous from the central section, and the radius of curvature of the tread tread in the tire width direction cross section is the center A vibration absorbing rubber that is smaller in the side area than the area and has a lower modulus than the tread rubber that forms the tread in each of the central area and the side area between the carcass and the tread is disposed. It is characterized by.

Next, the operation of the agricultural machine tire according to claim 1 will be described.
Displacement in the radial direction of the tire in the central and side sections is increased by placing vibration absorbing rubber that absorbs vibration in the tread central section and the tread side section between the carcass and tread. In addition, the contact pressure distribution in these areas can be made more uniform than that of, for example, an agricultural machine tire in which vibration absorbing rubber is disposed only in the tread central area, and the pattern pitch component, more specifically, RFV can be reduced. .
Since the vibration ride comfort performance is improved by reducing the RFV, the vibration ride comfort performance, particularly when traveling on a good road, can be improved without lowering the traction performance. The tread surface refers to a surface that contacts the road surface of the tread, and here, refers to a tread surface.

  The agricultural machine tire according to claim 2 of the present invention is the agricultural machine tire according to claim 1, wherein a central area of the tread straddles the tire equatorial plane and satisfies a range of 40 to 60% of the tread width. It is characterized by.

Next, the operation of the agricultural machine tire according to claim 2 will be described.
For example, when the tread surface in the center area of the tread is generally flat in the tire width direction in the tire cross section, if the center area of the tread is less than 40% of the tread width, the flat portion decreases and the lag contributes to traction. If the tread central area exceeds 60% of the tread width, the flat area increases and the lag projection area increases and the traction improves. Since the drop height from the road surface in the part area decreases, the LFV deteriorates and the vibration ride comfort performance deteriorates. Therefore, it is preferable that the center area of the tread straddles the tire equator and satisfies the range of 40 to 60% of the tread width.

  The agricultural machine tire according to claim 3 of the present invention is the agricultural machine tire according to claim 1 or 2, wherein 100% modulus of the vibration absorbing rubber is 30 to 100% modulus of the tread rubber. It is characterized by satisfying 70%.

Next, the operation of the agricultural machine tire according to claim 3 will be described.
In general, the displacement of rubber is determined by the physical properties of the modulus. Therefore, if the 100% modulus of the vibration absorbing rubber exceeds 70% of the 100% modulus of the tread rubber, the tire radial direction in the tread central area and the tread side area The displacement is reduced, and the contact pressure in the central area and the side area in the tread is sufficiently lowered, and the effect of making it uniform cannot be obtained. Also, if the 100% modulus of the vibration-absorbing rubber is less than 30% of the 100% modulus of the tread rubber, the displacement in the tire radial direction in the tread central area and the tread side area becomes large, and the central area and side part in the tread The contact pressure of the area becomes high, and the effect of equalizing the contact pressure cannot be obtained. Therefore, the 100% modulus of the vibration absorbing rubber preferably satisfies 30 to 70% of the 100% modulus of the tread rubber.

  The agricultural machine tire according to claim 4 of the present invention is the agricultural machine tire according to any one of claims 1 to 3, wherein the maximum thickness of the vibration-absorbing rubber in the side area of the tread. Satisfying 5 to 20% of the groove depth of the lug groove between the lugs adjacent in the tire circumferential direction in the tread hump portion, and the maximum thickness of the vibration absorbing rubber in the central area of the tread is It is characterized by satisfying 10 to 40% of the groove depth on the equator plane.

Next, the operation of the agricultural machine tire according to claim 4 will be described.
If the maximum thickness of the vibration absorbing rubber in the tread side section exceeds 20% of the groove depth of the lug groove in the tread hump section, the tire radial displacement of the vibration absorbing rubber in the side section becomes too large, and the ground contact The pressure drops too much to make the contact pressure uniform, and as a result, the vibration ride comfort performance cannot be improved. Moreover, the influence on uneven wear performance comes out because ground pressure falls too much. On the other hand, when the maximum thickness of the vibration absorbing rubber in the side area is less than 5% of the groove depth of the lug groove in the tread hump, the radial displacement of the vibration absorbing rubber is reduced, and the sufficient effect of reducing the contact pressure is achieved. Cannot be obtained, and the contact pressure cannot be made uniform.

  If the maximum thickness of the vibration absorbing rubber in the tread central area exceeds 40% of the groove depth on the equator surface of the lug groove, the radial displacement of the vibration absorbing rubber in the central area becomes too large, and the ground contact The pressure drops too much to make the contact pressure uniform, and as a result, the vibration ride comfort performance cannot be improved. Moreover, the influence on uneven wear performance comes out because ground pressure falls too much. On the other hand, if the maximum thickness of the vibration absorbing rubber in the central area is less than 10% of the groove depth on the equatorial plane of the lug groove, the displacement of the vibration absorbing rubber in the tire radial direction will be small, and the sufficient effect of lowering the contact pressure Cannot be obtained, and the contact pressure cannot be made uniform.

  Therefore, the maximum thickness of the vibration absorbing rubber in the tread side region satisfies 5 to 20% of the groove depth of the lug groove in the tread hump portion, and the maximum thickness of the vibration absorbing rubber in the tread central region is It is preferable to satisfy 10 to 40% of the groove depth on the equator plane. In addition, the tread hump part said here has shown the position where the thickness of a tread becomes the maximum.

  The agricultural machine tire according to claim 5 of the present invention is the agricultural machine tire according to any one of claims 1 to 4, wherein the vibration-absorbing rubber in the central area of the tread and the side portion of the tread are provided. It is characterized by continuous vibration absorbing rubber in the area.

Next, the effect | action of the tire for agricultural machines of Claim 5 is demonstrated.
Since the vibration absorbing rubber is continuous from the center area to the side area of the tread, the contact pressure is further uniformized.

  The tire for agricultural machinery of the present invention can improve the vibration riding comfort performance, in particular, the vibration riding comfort performance when traveling on a good road, without reducing the traction performance.

[First Embodiment]
(Configuration) Next, a first embodiment of the tire for agricultural machinery according to the present invention will be described with reference to FIGS. The agricultural tire of the present embodiment is a pneumatic tire 10 (hereinafter, tire 10) for agricultural machinery for agricultural vehicles (for example, agricultural tractors and the like), and its internal structure is a bias structure. FIG. 1 is a plan view showing a tread pattern of an agricultural machine tire according to the present embodiment. 2 is a cross-sectional view taken along line 2-2 of FIG.

  As shown in FIG. 2, the tire 10 includes a first carcass ply 12 and a second carcass ply 14 in which a cord extending in a direction intersecting with the tire equatorial plane CL (hereinafter, the equatorial plane CL) is embedded. The carcass 16 is provided. In the present embodiment, the carcass 16 has a structure in which two carcass plies overlap each other. However, in other embodiments, the carcass 16 may include a plurality of carcass plies.

(Carcass)
The first carcass ply 12 and the second carcass ply 14 are respectively wound up around the bead core 20 in which both end portions are embedded in the bead portion 18 from the tire inner side to the outer side.
The first carcass ply 12 is formed by embedding a plurality of cords (for example, an organic fiber cord such as nylon or a metal fiber cord such as steel) that extend in a direction intersecting the equator plane CL in the coated rubber in parallel. is there. The second carcass ply 14 is also formed by embedding a plurality of cords (for example, an organic fiber cord such as nylon or a metal fiber cord such as steel) that extend in a direction intersecting the equator plane CL in the covering rubber in parallel. is there. Further, the cord of the first carcass ply 12 and the cord of the second carcass ply 14 intersect each other and are inclined in opposite directions with respect to the equator plane CL.

(tread)
A tread 22 is provided outside the carcass 16 in the tire radial direction. The tread 22 is formed from a tread rubber 24. The tread 22 has a plurality of protruding lugs 26 that extend while inclining from the center in the tire width direction toward the side. The lugs 26 are alternately formed on the left and right sides of the equatorial plane CL at predetermined intervals in the tire circumferential direction. Specifically, the lug 26 includes a first lug 26A disposed on one side across the equator plane CL and a second lug 26B disposed on the other side across the equator plane CL. Yes. Note that the concave portion of the tread 22 other than the lug 26 is referred to as a lug groove 28. In the tread surface of the tread 22 of the present embodiment, the end portion on the outer side in the tire width direction is on the inner side in the tire radial direction with respect to the equatorial plane CL in the cross section in the tire width direction, and the groove depth of the lug groove 28 of the tread 22 is the equatorial plane. It is deeper from CL toward the outer end of the tread 22 in the tire width direction.

  As shown in FIG. 2, the tread 22 includes a central area 40 that straddles the equator plane CL, and side areas 42 that are continuously arranged in the central area 40 on both sides of the central area 40 in the tire width direction. Further, the radius of curvature of the tread surface of the tread 22 in the tire width direction cross section is made smaller in the side section 42 than in the central section 40. That is, since the tread tread surface of the tread 22 and the tread surface 27 of the lug 26 are the same, the first curvature radius R1 of the tread surface corresponding to the central area 40 of the first lug 26A and the second lug 26B is It means that it is larger than the second curvature radius R2 of the tread of the portion corresponding to the side area 42 of the first lug 26A and the second lug 26B.

  The lug 26 has a lug outer wall 46 that extends inward in the tire radial direction from the outermost end surface 44 of the tread surface 27 in the tire width direction. In the present embodiment, since the tread outer end 44 of the lug 26 is angular in the tire width direction cross section, the tread outer end 44A of the first lug 26A and the tread outer end 44B of the second lug 26B The distance along the tire width direction is the tread width TW. Further, for example, as shown in FIG. 5, when the tread outer end 44 of the lug 26 is not angular in the tire width direction cross section (for example, in an arc shape), the tread 27A (curvature radius R2 portion) of the first lug 26A The first intersection of the extension line (two-dot chain line) and the extension line (two-dot chain line) of the lug outer wall 46A, the extension line of the tread 27B of the second lug 26B, and the extension line of the lug outer wall 46B The distance along the tire width direction with the intersection of 2 points to the tread width TW.

Moreover, it is preferable that the center area 40 of the tread 22 satisfies the range of 40 to 60% of the tread width TW. In addition, as shown in FIG. 2, the range of the center area 40 of the tread 22 is measured along the tire width direction.
Furthermore, it is preferable that the first radius of curvature R1 is set to be not less than twice the tire radius indicated by the symbol H. In the present embodiment, the first radius of curvature R1 is set to be infinite, that is, a straight line.
Furthermore, when the distance in the tire radial direction between the tread outer end 44 of the lug 26 and the point on the equator CL of the tread 22 that is the maximum tire diameter is a drop height H1, the drop height H1 is 6 of the tread width TW. It is preferable to set the second radius of curvature R2 to be -10%.

(Vibration absorbing rubber)
A first vibration absorbing rubber 32 having a modulus lower than that of the tread rubber 24 is disposed at a position corresponding to the central area 40 between the carcass 16 and the tread 22. A second vibration absorbing rubber 34 having a modulus lower than that of the tread rubber 24 is disposed at a position corresponding to the side area 42 between the carcass 16 and the tread 22. The 100% modulus of the first vibration absorbing rubber 32 preferably satisfies 30 to 70% of the 100% modulus of the tread rubber 24, and the 100% modulus of the second vibration absorbing rubber 32 is 100% of the tread rubber 24. It is preferable to satisfy 30 to 70% of the modulus.

  In the present embodiment, the first vibration absorbing rubber 32 and the second vibration absorbing rubber 34 are made of the same rubber material. However, the present invention is not limited to this structure. In other embodiments, the first vibration absorbing rubber 32 and the second vibration absorbing rubber 34 are the first. The vibration absorbing rubber 32 and the second vibration absorbing rubber 34 may be made of different rubber materials.

  The maximum thickness T1 of the first vibration absorbing rubber 32 is preferably 10 to 40% of the groove depth D1 of the lug groove 28 on the equator plane CL. The maximum thickness of the second vibration absorbing rubber 34 is T2 is preferably 5 to 20% of the groove depth D2 at the tread hump portion. Here, the thickness of the vibration absorbing rubber indicates the distance measured in the vertical direction from the surface of the carcass 16, and the groove depth of the lug groove 28 is the distance measured in the vertical direction from the tread 27 (tread tread) of the lug 26. Pointing. In the present embodiment, the tread hump portion is the tread outer end portion 44 of the lug 26.

  The width W1 of the first vibration absorbing rubber 32 preferably satisfies 30 to 100% of the central area 40, and the width W2 of the second vibration absorbing rubber 34 is 30 to 100% of the side area 42. Preferably there is. Here, the width of the vibration absorbing rubber refers to a distance measured along the tire width direction of the innermost portion in the tire width direction and the outermost portion in the tire width direction of the vibration absorbing rubber.

  As shown in FIG. 2, the first vibration absorbing rubber 32 and the second vibration absorbing rubber 34 of the present embodiment have a shape in which the end side gradually becomes narrower as the cross-sectional shape approaches the end of the trapezoidal base. However, it is not necessary to be limited to this configuration, and the cross-sectional shape of these vibration absorbing rubbers may be rectangular as shown in FIG.

  Further, in the present embodiment, as shown in FIG. 4, the unvulcanized first vibration absorbing rubber 32G and the unvulcanized second vibration absorbing rubber 34G are partially arranged in the unvulcanized tread 22G. As described above, the tire 10 may be molded using a DT tread formed by integrally extruding these tire constituent members, and the unvulcanized first vibration is applied to the unvulcanized carcass as in the conventional manner. After the absorption rubber and the unvulcanized second vibration absorption rubber are laminated, an unvulcanized tread may be laminated to form an unvulcanized tire. When the tire 10 is molded using the DT tread, the risk of entering air can be suppressed lower than when the respective tire constituent members are laminated as separate bodies.

(Operation) According to the tire 10 of the present embodiment, the first vibration absorbing rubber 34 is disposed in a portion corresponding to the central area 40 between the carcass 16 and the tread 22, and the space between the carcass 16 and the tread 22 is arranged. By disposing the second vibration absorbing rubber 34 that absorbs vibrations at the portion corresponding to the side area 42, the displacement in the tire radial direction in the central area 40 and the side area 42 is increased. Can be made more uniform than the tire in which the first vibration absorbing rubber 32 is disposed only in the central area 40, and the pattern pitch component, more specifically, RFV can be reduced. Since the vibration ride comfort performance is improved by reducing the RFV, the vibration ride comfort performance, particularly when traveling on a good road, can be improved without lowering the traction performance.

  If the range of the central area 40 is less than 40% of the tread width TW, the flat portion is reduced, leading to a reduction in the lug projection area contributing to the traction, resulting in a decrease in traction, and the range of the central area 40 is less than the tread width TW. If the range exceeds 60%, the flat portion increases and the lag projection area increases and the traction improves. However, the fall height H1 from the road surface in the side section 42 decreases, leading to LFV deterioration and vibration ride comfort. Performance deteriorates. Therefore, it is preferable that the central area 40 of the tread 22 satisfies a range of 40 to 60% of the tread width TW.

  When the 100% modulus of the first vibration absorbing rubber 32 exceeds 70% of the 100% modulus of the tread rubber 24, the displacement in the tire radial direction in the central area 40 and the side area 42 is reduced. The effect of making the contact pressure in the side section 42 sufficiently low and uniform cannot be obtained. If the 100% modulus of the first vibration absorbing rubber 32 is less than 30% of the 100% modulus of the tread rubber 24, the displacement in the tire radial direction in the central section 40 and the side section 42 becomes large, and the tread 22 In this case, the ground pressure in the central area 40 and the side area 42 is increased, and the effect of equalizing the ground pressure cannot be obtained. Therefore, the 100% modulus of the first vibration absorbing rubber 32 preferably satisfies 30 to 70% of the 100% modulus of the tread rubber 24.

  When the maximum thickness T1 of the first vibration absorbing rubber 32 exceeds 40% of the groove depth D1 on the equator plane CL, the tire radial displacement of the first vibration absorbing rubber 32 in the central area 40 increases. Therefore, the contact pressure is too low to make the contact pressure uniform, and as a result, the vibration ride comfort performance cannot be improved. Moreover, the influence on uneven wear performance comes out because ground pressure falls too much. On the other hand, if the groove depth is less than 10% of the depth D1, the displacement of the first vibration absorbing rubber 32 in the tire radial direction is reduced, and a sufficient effect of lowering the contact pressure cannot be obtained, making it impossible to equalize the contact pressure. .

  If the maximum thickness T2 of the second vibration absorbing rubber 34 exceeds 20% of the groove depth D2 at the tread hump portion, the tire radial displacement of the second vibration absorbing rubber 34 becomes too large, and the contact pressure As a result, the ground contact pressure cannot be made uniform, and as a result, the vibration riding comfort performance cannot be improved. Moreover, the influence on uneven wear performance comes out because ground pressure falls too much. On the other hand, if the groove depth is less than 5% of the depth D2, the displacement of the second vibration absorbing rubber 34 in the tire radial direction is reduced, so that a sufficient effect of reducing the contact pressure cannot be obtained and the contact pressure cannot be made uniform. .

  Therefore, the maximum thickness T1 of the first vibration absorbing rubber 32 satisfies 10 to 40% of the groove depth D1 on the equator plane CL, and the maximum thickness T2 of the second vibration absorbing rubber 34 is the tread hump. It is preferable to satisfy 5 to 20% of the groove depth D2 at the portion.

  Further, when the width W1 of the first vibration absorbing rubber 32 is less than 30% of the central area 40, the displacement in the tire radial direction by the first vibration absorbing rubber 32 becomes small, and the contact pressure in the central area 40 is reduced. When the reduction is not obtained and the width W2 of the second vibration absorbing rubber 34 is less than 30% of the side section 42, the displacement in the tire radial direction by the second vibration absorbing rubber 34 becomes small, and the side A reduction in the contact pressure in the partial area 42 cannot be obtained. Accordingly, the width W1 of the first vibration absorbing rubber 32 preferably satisfies 30 to 100% of the central area 40, and the width W2 of the second vibration absorbing rubber 34 satisfies 30 to 100% of the side area 42. Is preferred.

[Other embodiments]
In the first embodiment, the internal structure of the tire 10 is a bias structure, and each vibration absorbing rubber is disposed on the outer side in the tire radial direction of the carcass 16. However, the present invention is not limited to this configuration. When the breaker is disposed on the radially outer side, it is preferable to dispose each vibration absorbing rubber between the tread 22 and the breaker.

  In the first embodiment, the internal structure of the tire 10 is configured as a bias structure. However, the present invention is not limited to this structure, and the internal structure may be configured as a radial structure. One or a plurality of belts or the like having an effect for suppressing the expansion in the tire radial direction may be disposed outside the 16 tire radial directions.

  In the first embodiment, the first vibration absorbing rubber 32 and the second vibration absorbing rubber 34 are separate from each other. However, the first vibration absorbing rubber 32 and the second vibration absorbing rubber 34 are not necessarily limited to this configuration. The second vibration absorbing rubber 34 may be a single vibration absorbing rubber layer formed integrally. In this case, since the first vibration absorbing rubber 32 and the second vibration absorbing rubber 34 are continuous in the range from the central area 40 to the side area 42 of the tread, the ground pressure is further uniformized.

[Test example]
In order to confirm the performance improvement effect of the present invention, one type of tire of a conventional example and one type of tire of an example to which the present invention was applied were prepared, and vibration measurement by a measuring instrument and vibration ride performance were evaluated. . The purpose of the test is to evaluate whether the vibration ride performance has been improved.

  Next, the test tire will be described. All of the test tire sizes are AGS 13.6-26 4PR T13H tires, and each test tire is assembled on a standard rim specified in JATMA YEAR BOOK (2006 edition, Japan Automobile Tire Association Standard). Used for testing. Table 1 shows the specifications of the test tire.

In a test related to comparative evaluation, vibration (amplitude level) was measured using a measuring instrument. Furthermore, these test tires were mounted on agricultural vehicles and one person was on board, and the passengers evaluated the feeling. The test conditions for comparative evaluation are as follows.
<Vibration ride performance actual vehicle test>
Traveling road type: Concrete paved road Traveling speed: 16km / h (straight running)
Agricultural vehicle type: agricultural tractor (41 hp)
The evaluation value of the vibration measurement is shown in Table 2 as an index display in which the vibration level (amplitude) of the conventional example is 100. Moreover, it is assumed that the smaller the evaluation value, the better the result.

  As shown in Table 2, in the measurement of the vibration level (amplitude) using the measuring instrument, the vibration level of the example is greatly reduced. Furthermore, it was confirmed that the vibration level (amplitude) of the example was lowered to a level that does not cause a problem even in the feeling evaluation by the occupant.

It is a top view which shows the tread pattern of the tire for agricultural machines which concerns on a 1st Example. It is 2-2 sectional drawing of FIG. It is sectional drawing which shows the other shape of the vibration absorption rubber used for the tire for agricultural machines which concerns on a 1st Example. It is sectional drawing which shows the unvulcanized tread of the tire for agricultural machines which concerns on a 1st Example. It is sectional drawing which shows the other shape of the edge part of the tread of the tire for agricultural machines which concerns on a 1st Example.

Explanation of symbols

10 Tire (Agricultural machinery tire)
16 carcass 20 bead core 22 tread 24 tread rubber 26 lug 27 tread (tread tread)
28 Lug groove 32 First vibration absorbing rubber (vibration absorbing rubber)
34 Second vibration absorbing rubber (vibration absorbing rubber)
40 Central area 42 Side area CL Equatorial plane (tire equatorial plane)
T1 Maximum thickness of the first vibration absorbing rubber T2 Maximum thickness of the second vibration absorbing rubber D1 Groove depth of the lug groove D2 Groove depth of the lug groove R1 First radius of curvature (curvature radius)
R2 Second radius of curvature (curvature radius)
TW tread width

Claims (5)

A carcass extending like a toroid between a pair of bead cores;
A tread having a plurality of lugs provided on the radially outer side of the carcass and extending incline in the tire circumferential direction from the central part in the tire width direction toward the side part,
The tread consists of a central area and side areas continuous from the central area,
In the tire width direction cross section, the radius of curvature of the tread surface is smaller in the side area than in the central area,
A tire for an agricultural machine, wherein a vibration absorbing rubber having a modulus lower than that of the tread rubber forming the tread is disposed in each of the central area and the side area between the carcass and the tread.   2. The agricultural machine tire according to claim 1, wherein a central area of the tread satisfies a range of 40 to 60% of a tread width across the tire equatorial plane.   The tire for agricultural machinery according to claim 1 or 2, wherein 100% modulus of the vibration absorbing rubber satisfies 30 to 70% of 100% modulus of the tread rubber.   The maximum thickness of the vibration absorbing rubber in the side area of the tread satisfies 5 to 20% of the groove depth of the lug groove between the lugs adjacent in the tire circumferential direction in the tread hump part, and the central area of the tread 4. The agriculture according to claim 1, wherein the maximum thickness of the vibration-absorbing rubber satisfies 10 to 40% of the groove depth on the equator plane of the lug groove. 5. Mechanical tire. The agricultural machine tire according to any one of claims 1 to 4, wherein the vibration absorbing rubber in the central area of the tread and the vibration absorbing rubber in the side area of the tread are continuous. .

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