JP2009269433A - Tire with lug, and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire for an agricultural machine, enhancing the vibration ride quality performance, in particular, the vibration ride quality performance during the travel on a smooth road without degrading the traction performance. <P>SOLUTION: A first center vibration absorbing rubber layer 32A and a second center vibration absorbing rubber layer 32B having the modulus lower than that of a tread rubber 24 are arranged within a lug 26 corresponding to a center area 40 of a tire 10 comprising a bead core 20 and a carcass 16, a tread 22 provided on the outer side in the radial direction of the carcass 16 and a plurality of lugs 26 formed in the tread 22. A first side vibration absorbing rubber layer 34A and a second side vibration absorbing rubber layer 34B having the modulus lower than that of the tread rubber 24 are arranged within the lug 26 corresponding to a side area 42. Thus, the vibration ride quality performance is enhanced without degrading the traction performance. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a tire with a lug in which a plurality of lugs are formed on a tread, and more particularly to a tire with a lug suitable for an agricultural vehicle that travels in a field such as a wetland, a soft ground, and a muddy land, and a method for manufacturing the tire with a lug. .

  2. Description of the Related Art Conventionally, as a tire with a lug in which a plurality of lugs are formed in a square shape with a predetermined interval in a tread, there are agricultural machinery tires and the like. In agricultural machinery tires, in order to ensure traction performance, which is a basic performance, the tread width is set as wide as possible, for example, the tread width is generally set wider than the total width of the tire. However, since tires for agricultural machinery have a trade-off relationship between traction performance and vibration ride comfort performance, there is a problem in that vibration ride comfort performance must be sacrificed in order to ensure a predetermined traction performance.

In order to solve this problem, various methods for improving the vibration ride comfort performance of agricultural machine tires have been proposed and implemented (see, for example, Patent Document 1 and Patent Document 2). Further, as one method for improving the vibration ride comfort performance, a technique is known in which lugs are formed so that the lugs partially overlap each other when viewed from the tire circumferential direction or the tire width direction.
JP 2006-224784 A JP 2004-299459 A

  By the way, in recent years, agricultural vehicles (for example, agricultural tractors, etc.) equipped with agricultural machinery tires have also increased opportunities to travel on good roads such as paved roads. Vibration ride comfort performance is gaining attention. As described above, various methods for improving the vibration riding comfort performance of agricultural machinery tires have been proposed and realized, but with these methods, the user satisfies the vibration riding comfort performance that is in a trade-off relationship with traction performance. It cannot be improved to the level.

  In recent years, agricultural machinery tires have been provided that increase the vibration ride comfort without substantially reducing the traction performance by making the total width of the tire and the tread width substantially the same. Insufficient and there is a strong demand in the market to provide agricultural machinery tires with further improved vibration ride performance.

  In view of the above, the present invention provides a lug-equipped tire and a lug-equipped tire manufacturing method that improve vibration ride comfort performance, particularly vibration ride comfort performance on a good road, without reducing traction performance. The purpose is to do.

  Considering that the traction performance and the vibration ride performance described above are in a trade-off relationship in a tire with a lug (so-called lug pattern tire), the inventor has determined both the traction performance and the vibration ride performance. The method of maintaining and improving was examined. Generally, a decrease in vibration ride comfort performance of an agricultural vehicle equipped with a lug-equipped tire is mainly caused by a pitch component based on a tread pattern (hereinafter referred to as a pattern pitch component).

  Particularly in the case of tires with lugs, the tread contact pressure distribution is W-shaped and tends to be large. This means that the contact pressure tends to be high at the center of the tread (near the tire equator) and near the end of the tread. That is, the contact pressure of the lug near the tire equatorial plane and the end of the lug on the outer side in the tire width direction are likely to be high. Thus, the inventor has completed the present invention by paying attention to the fact that the pattern pitch component causes vibration due to rolling of the tire with lugs, specifically, radial force variation (hereinafter referred to as RFV).

  Therefore, in the tire with a lug according to claim 1, in the tire width direction cross-section, the tread having a radius of curvature of the tread contacting the road surface is smaller in the side area continuous from the central area than the central area straddling the tire equator plane, A plurality of lugs formed on the tread and extending from a central portion of the tread in a tire width direction toward a side portion; an interior of the lug corresponding to the central region; and an interior of the lug corresponding to the side region. A vibration absorbing rubber layer that is provided in plural at intervals in the tire radial direction and has a lower modulus than the tread rubber forming the tread.

  In the tire with a lug according to claim 1, the inside of the lug corresponding to the central area of the tread (hereinafter referred to as the tread central area) and the inside of the lug corresponding to the side area of the tread (hereinafter referred to as the tread side area). Since multiple vibration absorbing rubber layers with a lower modulus than the tread rubber are provided at intervals in the tire radial direction, the displacement in the tire radial direction (tire radial direction) of the tread central area and the tread side area during loading increases. As a result, the contact pressure distribution of the tread becomes uniform. Thereby, the vibration (specifically, RFV) at the time of rolling of the tire with the lug is reduced, and the vibration riding comfort performance is improved. From the above, the lug-equipped tire of the present invention can improve the vibration riding comfort performance, particularly the vibration riding comfort performance when traveling on a good road, without reducing the traction performance. Further, by providing a plurality of vibration absorbing rubber layers at intervals in the tire radial direction, it becomes easier to finely adjust the contact pressure of the tread than a tire in which only one vibration absorbing rubber layer is disposed. That is, it becomes easy to make the contact pressure distribution of the tread uniform. In addition, the tread surface of the lug is included in the tread surface.

  In the tire with a lug according to claim 2, the central area of the tread satisfies a range of 40 to 60% of the tread width.

  In the tire with a lug according to claim 2, for example, in the cross section in the tire width direction, when the tread in the tread central area is flat along the tire width direction, the tread central area is less than 40% of the tread width. Since the flat portion is reduced, the projected area of the lag contributing to the traction property is reduced, and the traction property is lowered. In addition, if the range of the tread central area exceeds 60% of the tread width, the flat part increases and the lag projection area increases, improving the traction, but the tread side area from the flat part of the tread central area is improved. Since the falling height to the end portion is reduced, the lateral force variation (LFV) is deteriorated and the vibration riding comfort performance is deteriorated. Therefore, it is preferable that the tread central area satisfies the range of 40 to 60% of the tread width.

  Generally, the displacement of rubber is determined by the modulus physical properties. Therefore, in the tire with a lug according to claim 3, the 100% modulus of the vibration absorbing rubber layer satisfies the range of 30 to 70% of the 100% modulus of the tread rubber.

  In the tire with a lug according to claim 3, when the 100% modulus of the vibration absorbing rubber layer exceeds 70% of the 100% modulus of the tread rubber, the displacement in the tire radial direction of the tread central area and the tread side area becomes small. Thus, the effect of making the contact pressure distribution uniform while reducing the contact pressure of the tread cannot be sufficiently obtained. If the 100% modulus of the vibration absorbing rubber layer is less than 30% of the 100% modulus of the tread rubber, the displacement in the tire radial direction of the tread central area and the tread side area becomes too large, and the tread contact pressure drops. Thus, the effect of making the contact pressure distribution uniform cannot be obtained. Accordingly, the 100% modulus of the vibration absorbing rubber layer preferably satisfies 30 to 70% of the 100% modulus of the tread rubber.

  The tire with lugs according to claim 4, wherein the sum of the maximum thicknesses of the vibration absorbing rubber layers inside the lugs corresponding to the side areas is the lugs between the lugs adjacent in the tire circumferential direction in the tread hump portion. The sum of the maximum thicknesses of the vibration-absorbing rubber layers inside the lug corresponding to the central area, which satisfies the range of 5 to 20% of the groove depth, is the groove depth on the tire equatorial plane of the lug groove. Of 10 to 40%.

  In the tire with a lug according to claim 4, when the total of the maximum thickness of the vibration absorbing rubber layer inside the lug corresponding to the tread side region exceeds 20% of the groove depth of the lug groove in the tread hump portion, The displacement in the tire radial direction in the tread side area becomes too large, and the contact pressure is too low, and the effect of making the contact pressure distribution uniform cannot be obtained sufficiently. As a result, the vibration ride comfort performance cannot be sufficiently improved. Moreover, the influence on uneven wear performance comes out because ground pressure falls too much. On the other hand, when the sum of the maximum thicknesses of the vibration absorbing rubber layers inside the lug corresponding to the tread side section is less than 5% of the groove depth of the lug groove in the tread hump section, the tire radial direction of the tread side section Since the displacement becomes too small, the effect of reducing the contact pressure cannot be obtained sufficiently, and the contact pressure distribution cannot be made uniform.

  Also, if the sum of the maximum thicknesses of the vibration absorbing rubber layers inside the lug corresponding to the tread central area exceeds 40% of the groove depth on the tire equatorial plane of the lug groove, the tire radial displacement of the tread central area Becomes too large, the contact pressure drops too much, and the effect of making the contact pressure distribution uniform cannot be obtained sufficiently. As a result, the vibration ride comfort performance cannot be sufficiently improved. Moreover, the influence on uneven wear performance comes out because ground pressure falls too much. On the other hand, when the sum of the maximum thicknesses of the vibration absorbing rubber layers inside the lugs corresponding to the tread central area is less than 10% of the groove depth on the tire equatorial plane of the lug grooves, the tire radial displacement of the tread central area Becomes too small, and the effect of lowering the contact pressure cannot be obtained sufficiently, and the contact pressure distribution cannot be made uniform.

  Therefore, the sum of the maximum thicknesses of the vibration absorbing rubber layers inside the lug corresponding to the tread side area satisfies 5-20% of the groove depth of the lug groove in the tread hump, and the lug corresponding to the tread central area. It is preferable that the sum of the maximum thicknesses of the vibration absorbing rubber layers in the inside satisfies 10 to 40% of the groove depth on the equator plane of the lug groove. In addition, the tread hump part said here has shown the site | part where the thickness of a tread becomes the maximum.

  In the tire with a lug according to claim 5, the vibration absorbing rubber layer inside the lug corresponding to the central area and the vibration absorbing rubber layer inside the lug corresponding to the side area are continuous.

  In the tire with a lug according to claim 5, since the vibration absorbing rubber layer inside the lug corresponding to the tread central area and the vibration absorbing rubber layer inside the lug corresponding to the tread side area are continuous, Overall, the vibration absorbing effect can be enhanced.

  The method for manufacturing a tire with a lug according to claim 6 is the method for manufacturing a tire with a lug according to any one of claims 1 to 5, wherein the center region of the tread and the side region of the tread are provided. A step of integrally extruding an unvulcanized tread rubber and an unvulcanized vibration absorbing rubber so that the vibration absorbing rubber layer is disposed, and forming a plurality of strip-shaped first unvulcanized tread members; Extruding unvulcanized tread rubber to form a strip-shaped second unvulcanized tread member, and between the first unvulcanized tread member and the second unvulcanized tread member, And a step of stacking the first unvulcanized tread member and the second unvulcanized tread member so that a vibration-absorbing rubber for vulcanization is disposed.

  In the manufacturing method of the tire with a lug according to claim 6, first, unvulcanized tread rubber and unvulcanized vibration absorbing rubber are integrally extruded to form a plurality of belt-shaped first unvulcanized tread members. To do. Next, an unvulcanized tread rubber is extruded to form a belt-shaped second unvulcanized tread member. Then, the first unvulcanized tread member and the second unvulcanized tread member are arranged such that an unvulcanized vibration absorbing rubber is disposed between the first unvulcanized tread member and the second unvulcanized tread member. Stack the sulfur tread member. Thereby, the laminated body of the unvulcanized tread member in which the unvulcanized vibration absorbing rubber is disposed inside is molded. Here, in order to form the first unvulcanized tread member by integrally extruding the unvulcanized tread rubber and the unvulcanized vibration absorbing rubber, the air enters the first unvulcanized tread member ( Mixing of air) is suppressed. As a result, entry of air into the vulcanized tire is suppressed. In the unvulcanized tread laminate, a second unvulcanized tread member is disposed between one first unvulcanized tread member and another first unvulcanized tread member. You may overlap and form.

  The lug-equipped tire of the present invention can improve the vibration ride comfort performance, particularly the vibration ride comfort performance when traveling on a good road, without reducing the traction performance. Moreover, the lug-equipped tire produced by the method for producing a lug-equipped tire according to the present invention can improve the vibration ride comfort performance, particularly the vibration ride comfort performance when traveling on a good road, without lowering the traction performance.

[First Embodiment]
(Configuration) Next, a first embodiment of a lug-equipped tire according to the present invention will be described with reference to FIGS. In addition, the tire with a lug of this embodiment is a pneumatic tire 10 for an agricultural machine (hereinafter referred to as a tire 10) for an agricultural vehicle (for example, an agricultural tractor or the like), and its internal structure is a bias structure. FIG. 1 is a plan view showing a tread pattern of the tire 10 of the present embodiment, and FIG. 2 is a 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 is composed of two carcass plies, but the present invention is not limited to this structure, and the carcass 16 may be composed of one or three or more carcass plies. Good.

(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. There is also a second carcass ply 14 in which a plurality of cords (for example, an organic fiber cord such as nylon or a metal fiber cord such as steel) extending in a direction intersecting the equator plane CL are embedded in the coated rubber in parallel. It is. Further, the cords of the first carcass ply 12 and the cords 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 by a tread rubber 24. The tread 22 is formed with a plurality of protruding lugs 26 that extend while inclining in the tire circumferential direction from the center in the tire width direction toward the side (see FIG. 1). The lugs 26 are alternately arranged on the left and right sides of the equatorial plane CL at predetermined intervals in the tire circumferential direction. Specifically, the lug 26 is disposed on one side (left side in FIG. 1) with the equator plane CL in between, and on the other side (right side in FIG. 1) with the equator plane CL in between. And the second lug 26B. Note that the concave portion of the tread 22 other than the lug 26 is referred to as a lug groove 28. In addition, as shown in FIG. 2, in the cross section of the tire width direction, the tread 22 has a tread 22 with an end on the outer side in the tire width direction that is on the equator plane CL and an inner side in the tire radial direction. The groove depth of the tread 22 is deeper from the equator plane 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 continuous with the central area 40 on both sides in the tire width direction of the central area 40. Further, in the cross section in the tire width direction, the curvature radius (second curvature radius R2) of the tread 22 in the side section 42 is larger than the curvature radius (first curvature radius R1) of the tread 22 in the center section 40. It is getting smaller. That is, in this embodiment, since the tread 22 and the lug 26 have the same tread surface 27, the radius of curvature of the tread surface of the first lug 26A in the central area 40 is the first radius of curvature R1. This means that the radius of curvature of the tread surface of the first lug 26A in the side section 42 is the second radius of curvature R2. Similarly, the radius of curvature of the tread of the second lug 26B in the central section 40 is the first radius of curvature R1, and the radius of curvature of the tread of the second lug 26B of the side section 42 is the second radius of curvature. Means R2.

  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 indicates the tread width TW. Further, 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 the case of an arc), the tread 27A (curvature radius R2 portion) of the first lug 26A ) And a first intersection of an extension line (two-dot chain line) of the lug outer wall 46A, an extension line of the tread 27B (not shown) of the second lug 26B, and the lug outer wall 46B. The distance along the tire width direction with the second intersection with the extension line (not shown) indicates 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. The range of the central area 40 of the tread 22 is measured along the tire width direction as shown in FIG.
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 infinite, that is, a straight line along the tire width direction.
Furthermore, when the distance in the tire radial direction between the tread outer end 44 of the lug 26 and the point on the equatorial plane 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 layer)
As shown in FIG. 2, a central vibration absorbing rubber layer 32 made of a low modulus rubber having a modulus lower than that of the tread rubber 24 is spaced apart in the tire radial direction inside the lug 26 corresponding to the central section 40. Are provided. In the present embodiment, the central vibration absorbing rubber layer 32 is disposed at a distance from the first central vibration absorbing rubber layer 32A and the first central vibration absorbing rubber layer 32A on the outer side in the tire radial direction. It is composed of two vibration absorbing rubber layers and two central vibration absorbing rubber layers 32B. In other embodiments, the central vibration absorbing rubber layer 32 may be composed of three or more vibration absorbing rubber layers.

  In addition, a plurality of side vibration absorbing rubber layers 34 made of a low modulus rubber whose modulus is lower than that of the tread rubber 24 are provided in the lug 26 corresponding to the side area 42 at intervals in the tire radial direction. ing. In the present embodiment, the side vibration absorbing rubber layer 34 is disposed at a distance from the first side vibration absorbing rubber layer 34A and the first side vibration absorbing rubber layer 34A on the outer side in the tire radial direction. The vibration absorbing rubber layer is composed of two vibration absorbing rubber layers 34B and the second side vibration absorbing rubber layer 34B. In other embodiments, the side vibration absorbing rubber layer 34 may be composed of three or more vibration absorbing rubber layers.

  The low modulus rubber constituting the first central vibration absorbing rubber layer 32A, the low modulus rubber constituting the second central vibration absorbing rubber layer 32B, the low modulus rubber constituting the first side vibration absorbing rubber layer 34A, and the first It is preferable that the value of 100% modulus of each of the low modulus rubbers constituting the two-side vibration absorbing rubber layer 34B satisfies the range of 30 to 70% of the value of 100% modulus of the tread rubber 24.

  In this embodiment, the low modulus rubber constituting the first central vibration absorbing rubber layer 32A, the low modulus rubber constituting the second central vibration absorbing rubber layer 32B, and the low modulus constituting the first side vibration absorbing rubber layer 34A. The modulus rubber and the low modulus rubber constituting the second side vibration absorbing rubber layer 34B are the same kind of rubber material (that is, the value of 100% modulus is the same). Thereby, compared with the case where a multiple types of rubber material is used, manufacturing cost can be suppressed.

  As shown in FIG. 2, the distance between the first central vibration absorbing rubber layer 32A and the carcass 16 is substantially constant. Further, the distance between the first side vibration absorbing rubber layer 34A and the carcass 16 is also substantially constant. In other embodiments, the distance between the first central vibration-absorbing rubber layer 32A and the carcass 16 may not be substantially constant, and the carcass 16 and the inner layer in the tire radial direction of the first side vibration-absorbing rubber layer 34A may be used. The distance between and may not be substantially constant.

  The total maximum thickness G1 of the central vibration absorbing rubber layer 32 preferably satisfies a range of 10 to 40% of the groove depth D1 of the lug groove 28 on the equator plane CL. Specifically, the sum of the maximum thickness t1 of the first central vibration absorbing rubber layer 32A and the maximum thickness t2 of the second central vibration absorbing rubber layer 32B is the sum of the maximum thickness of the central vibration absorbing rubber layer 32. G1. Further, the total maximum thickness G2 of the side vibration absorbing rubber layer 34 preferably satisfies the range of 5 to 20% of the groove depth D2 at the tread hump portion. Specifically, the sum of the maximum thickness t3 of the first side vibration absorbing rubber layer 34A and the maximum thickness t4 of the second side vibration absorbing rubber layer 34B is the maximum thickness of the side vibration absorbing rubber layer 34. This is the total G2. Here, the thickness of the vibration absorbing rubber layer indicates the distance measured in the vertical direction from the surface of the carcass 16, and the groove depth of the lug groove 28 extends in the vertical direction from the tread surface 27 of the lug 26 (tread surface of the tread 22). Refers to the measured distance. In the present embodiment, the tread hump portion is the tread outer end portion 44 of the lug 26.

  The width W1 of the central vibration absorbing rubber layer 32 preferably satisfies the range of 30 to 100% of the central area 40, and the width W2 of the side vibration absorbing rubber layer 34 is 30 to 100% of the side area 42. It is preferable to satisfy the range. The width W1 of the central vibration absorbing rubber layer 32 refers to the distance measured along the tire width direction at the ends closest to the boundary between the central area 40 and the side area 42 of the central vibration absorbing rubber layer 32. The width W2 of the side vibration absorbing rubber layer 34 is such that the outermost end in the tire width direction and the inner end in the tire width direction (that is, the end closest to the boundary between the central area 40 and the side area 42). ) Is measured along the tire width direction (see FIG. 2).

  Further, as shown in FIG. 2, the interval S1 between the first central vibration absorbing rubber layer 32A and the second central vibration absorbing rubber layer 32B is preferably set to 20% or more of the groove depth D1. Further, it is preferable that the interval S2 between the first side vibration absorbing rubber layer 34A and the second side vibration absorbing rubber layer 34B is set to 2.5% or more of the groove depth D2.

  As shown in FIG. 2, in the present embodiment, in the tire width direction cross section, the first central vibration absorbing rubber layer 32A, the second central vibration absorbing rubber layer 32B, the first side vibration absorbing rubber layer 34A, and the first Each of the two side vibration absorbing rubber layers 34B has a shape (trapezoidal shape) that is tapered at both ends in the tire width direction. However, the present invention is not necessarily limited to this configuration, and as shown in FIG. 3, the first central vibration absorbing rubber layer 32 </ b> A, the second central vibration absorbing rubber layer 32 </ b> B, the first side in the tire width direction cross section. The partial vibration absorbing rubber layer 34A and the second side vibration absorbing rubber layer 34B may each have a shape (substantially rectangular shape) that stands out at both ends in the tire width direction.

  Next, the manufacturing method of the tire 10 of this embodiment is demonstrated. First, an unvulcanized carcass (not shown), an unvulcanized bead core (not shown), and an unvulcanized tire component are manufactured. Next, the unvulcanized tread rubber is arranged so that the first central vibration absorbing rubber layer 32A is disposed in the central area 40 of the tread 22 and the first side vibration absorbing rubber layer 34A is disposed in the side area 42. 24A, the first unvulcanized central vibration absorbing rubber 33A and the first unvulcanized side vibration absorbing rubber 35A are integrally extruded to form a first unvulcanized tread member 23A having a trapezoidal cross section. The molded first unvulcanized tread member 23A has a first unvulcanized central vibration absorbing rubber 33A and a first unvulcanized side vibration on the upper surface in a cross-sectional view (see a cross section in a direction orthogonal to the longitudinal direction). Absorbing rubber 35A is embedded (see FIG. 4A). Next, the unvulcanized tread rubber 24A is extruded to form a second unvulcanized tread member 23B having a trapezoidal cross section. Then, the uncured tread rubber 24A, the second vulcanized tread rubber 24A, the second central vibration absorbing rubber layer 32B is arranged in the central area 40 of the tread 22 and the second side vibration absorbing rubber layer 34B is arranged in the side area 42. The unvulcanized central vibration absorbing rubber 33B and the second unvulcanized side vibration absorbing rubber 35B are integrally extruded to form a third unvulcanized tread member 23C having a trapezoidal cross section. The molded third unvulcanized tread member 23 </ b> C has a second unvulcanized central vibration absorbing rubber 33 </ b> B and a second unvulcanized side vibration on the upper surface in a cross-sectional view (see a cross section in a direction orthogonal to the longitudinal direction). Absorbing rubber 35B is embedded. Further, a belt-shaped unvulcanized side tread 25A having a substantially triangular cross section is formed. The unvulcanized side tread 25A becomes the side tread 25 constituting the tire side part shown in FIG. 2 after vulcanization.

  Next, the unvulcanized carcass is made into a cylindrical shape to form an unvulcanized carcass band, unvulcanized bead cores are arranged at both ends of the unvulcanized carcass band, and both end portions are wound inward in the axial direction. An unvulcanized tire constituent member (for example, a bead filler) is disposed in the vicinity. Next, as shown in FIG. 4A, the first unvulcanized tread member 23A is overlaid on the unvulcanized carcass band (not shown) so that the bottom surface is in close contact therewith. Next, the second unvulcanized tread member 23B is stacked so that the bottom surface is in close contact with the upper surface of the first unvulcanized tread member 23A. Thus, the first unvulcanized central vibration absorbing rubber 33A and the first unvulcanized side vibration absorbing rubber 35A are disposed between the first unvulcanized tread member 23A and the second unvulcanized tread member 23B. . Next, the third unvulcanized tread member 23C is stacked so that the bottom surface is in close contact with the upper surface of the second unvulcanized tread member 23B. Thus, the second unvulcanized central vibration absorbing rubber 33B and the second unvulcanized side vibration absorbing rubber 35B are disposed between the second unvulcanized tread member 23B and the third unvulcanized tread member 23C. An unvulcanized tread 22A, which is a laminate of the first unvulcanized tread member 23A, the second unvulcanized tread member 23B, and the third unvulcanized tread member 23C, is formed.

  Next, the unvulcanized side tread 25A is laminated on the unvulcanized carcass band so that one end of the unvulcanized side tread 25A overlaps with both ends of the unvulcanized tread 22A. Thereby, a cylindrical unvulcanized tire case is formed. Then, the central portion is expanded radially outward while bringing both end portions of the unvulcanized tire case closer to each other, thereby making the unvulcanized tire case substantially toroidal. Thereafter, the tire 10 is manufactured by vulcanizing the unvulcanized tire case. When the lug groove 28 is formed by the vulcanization mold during the vulcanization molding, the vibration absorbing rubber positioned between the lugs 26 adjacent in the tire circumferential direction is compared with the vibration absorbing rubber disposed inside the lug 26. It becomes a thin and elongated shape.

  Here, the unvulcanized tread rubber 24A, the first unvulcanized central vibration absorbing rubber 33A, and the first unvulcanized side vibration absorbing rubber 35A are integrally extruded to form the first unvulcanized tread member 23A. Accordingly, for example, the unvulcanized tread rubber 24A, the first unvulcanized central vibration absorbing rubber 33A, and the second unvulcanized side vibration absorbing rubber 35A are separately formed into a band shape and then stacked. Rather than forming a member corresponding to the vulcanized tread member 23A, entry of air into the first unvulcanized tread member 23A is suppressed. Similarly, the entry of air into the third unvulcanized tread member 23C is also suppressed. As a result, entry of air into the tire 10 after vulcanization is suppressed.

  (Operation) Next, the operation of the tire 10 of this embodiment will be described. According to the tire 10, the first central vibration absorbing rubber layer 32 </ b> A and the second central vibration absorbing rubber layer 32 </ b> B are provided in the lug 26 corresponding to the central area 40 at intervals in the tire radial direction. Since the first side vibration absorbing rubber layer 34A and the second side vibration absorbing rubber layer 34B are disposed in the lug 26 corresponding to the tire in the radial direction of the tire, the central region 40 of the tread 22 at the time of loading is provided. And the displacement to the tire radial direction of the side part 42 increases, and the contact pressure distribution of the center area 40 and the side part 42 of the tread 22 becomes uniform. Thereby, vibration (specifically, RFV) at the time of rolling of the tire 10 is reduced, and vibration ride comfort performance is improved. As a result, the tire 10 can improve the vibration ride comfort performance, particularly the vibration ride comfort performance when traveling on a good road, without reducing the traction performance.

  In the tire 10, the first central vibration absorbing rubber layer 32 </ b> A and the second central vibration absorbing rubber layer 32 </ b> B are provided in the central area 40 at intervals in the tire radial direction, so that the vibration absorbing rubber layer is provided in the central area 40. It becomes easier to finely adjust the contact pressure of the tread than a tire in which only one layer is arranged. That is, rather than adjusting the arrangement position and the maximum thickness of only one vibration absorbing rubber layer, two vibration absorbing rubber layers are arranged like the tire 10 and one vibration absorbing rubber layer (first central vibration layer) is arranged. By adjusting the arrangement position, maximum thickness and modulus of the other vibration absorbing rubber layer (second central vibration absorbing rubber layer 32B) with reference to the absorbing rubber layer 32A), the ground pressure of the tread can be finely adjusted. it can. That is, it becomes easy to make the contact pressure distribution of the tread 22 uniform.

  Moreover, if the range of the central area 40 of the tread 22 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, and the traction is lowered. If the range of the central area 40 of the tread 22 exceeds 60% of the tread width TW, the flat portion increases, the lug projection area increases, and the traction is improved, but the drop height H1 from the road surface in the side area 42 increases. Therefore, the LFV is deteriorated and the vibration ride comfort performance is deteriorated. Therefore, the central area 40 of the tread 22 preferably satisfies a range of 40 to 60% of the tread width TW.

  The low modulus rubber constituting the first central vibration absorbing rubber layer 32A, the low modulus rubber constituting the second central vibration absorbing rubber layer 32B, the low modulus rubber constituting the first side vibration absorbing rubber layer 34A, and the first When the 100% modulus value of each of the low modulus rubbers constituting the two side vibration absorbing rubber layer 34B exceeds 70% of the 100% modulus value of the tread rubber 24, the central area 40 and the side areas 42 of the tread 22 are obtained. The displacement in the tire radial direction becomes too small, and the effect of making the contact pressure distribution uniform while reducing the contact pressure in the central section 40 and the side section 42 cannot be sufficiently obtained. The low modulus rubber constituting the first central vibration absorbing rubber layer 32A, the low modulus rubber constituting the second central vibration absorbing rubber layer 32B, the low modulus rubber constituting the first side vibration absorbing rubber layer 34A, and the first When the value of 100% modulus of each of the low modulus rubbers constituting the two side vibration absorbing rubber layer 34B is less than 30% of the value of 100% modulus of the tread rubber 24, the central area 40 and the side areas 42 of the tread 22 are obtained. Since the displacement in the tire radial direction becomes too large, the contact pressure in the central section 40 and the side section 42 falls too much, and the effect of making the contact pressure distribution uniform cannot be obtained. Therefore, the low modulus rubber constituting the first central vibration absorbing rubber layer 32A, the low modulus rubber constituting the second central vibration absorbing rubber layer 32B, the low modulus rubber constituting the first side vibration absorbing rubber layer 34A, and the first It is preferable that each 100% modulus value of the low modulus rubber constituting the two-side vibration absorbing rubber layer 34 </ b> B satisfies 30% to 70% of the 100% modulus value of the tread rubber 24.

  When the total C1 of the maximum thickness of the central vibration absorbing rubber layer 32 exceeds 40% of the groove depth D1 on the equator plane CL, the radial displacement of the central vibration absorbing rubber layer 32 in the central section 40 increases. Therefore, the contact pressure is too low, and the effect of making the contact pressure distribution uniform cannot be obtained sufficiently. 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 total maximum thickness G1 is less than 10% of the groove depth D1, the displacement in the tire radial direction of the central vibration absorbing rubber layer 32 becomes too small, and the effect of lowering the contact pressure cannot be obtained sufficiently, and the contact pressure distribution. Cannot be made uniform.

  If the total G2 of the maximum thickness of the side vibration absorbing rubber layer 34 exceeds 20% of the groove depth D2 at the tread hump portion, the tire radial displacement of the side vibration absorbing rubber layer 34 becomes too large. The ground pressure is too low, and the effect of making the ground pressure distribution uniform cannot be obtained sufficiently. 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 total G2 of the maximum thickness is less than 5% of the groove depth D2, the displacement in the tire radial direction of the side vibration absorbing rubber layer 34 becomes too small, and the effect of reducing the contact pressure cannot be obtained sufficiently. The distribution cannot be made uniform.

  Therefore, the total maximum thickness G1 of the central vibration absorbing rubber layer 32 satisfies 10 to 40% of the groove depth D1 on the equator plane CL, and the total maximum thickness G2 of the side vibration absorbing rubber layer 34 is It is preferable to satisfy 5 to 20% of the groove depth D2 at the tread hump portion.

  When the width W1 of the central vibration absorbing rubber layer 32 is less than 30% of the central area 40, the displacement in the tire radial direction by the central vibration absorbing rubber layer 32 becomes too small, and the contact pressure in the central area 40 can be sufficiently reduced. Further, when the width W2 of the side vibration absorbing rubber layer 34 is less than 30% of the side section 42, the displacement in the tire radial direction by the side vibration absorbing rubber layer 34 becomes too small, and the side section 42 The grounding pressure cannot be reduced sufficiently. Accordingly, the width W1 of the central vibration absorbing rubber layer 32 preferably satisfies the range of 30 to 100% of the central area 40, and the width W2 of the side vibration absorbing rubber layer 34 is in the range of 30 to 100% of the side area 42. It is preferable to satisfy.

When the distance S1 between the first central vibration absorbing rubber layer 32A and the second central vibration absorbing rubber layer 32B is less than 20% of the groove depth D1, the first central vibration absorbing rubber layer 32A and the second central vibration absorbing rubber layer 32A. Since the layer 32B is not substantially integrated with the layer 32B, the effect of finely adjusting the ground pressure cannot be obtained. Further, when the distance S2 between the first side vibration absorbing rubber layer 34A and the second side vibration absorbing rubber layer 34B is less than 2.5% of the groove depth D2, the first side vibration absorbing rubber layer 34A. And the second side vibration-absorbing rubber layer 34B are not substantially integrated with each other, so that the effect of finely adjusting the ground pressure cannot be obtained. Therefore, it is preferable that the interval S1 between the first central vibration absorbing rubber layer 32A and the second central vibration absorbing rubber layer 32B is set to 20% or more of the groove depth D1. Further, it is preferable that the interval S2 between the first side vibration absorbing rubber layer 34A and the second side vibration absorbing rubber layer 34B is set to 2.5% or more of the groove depth D2.
[Other embodiments]

  In the first embodiment, the internal structure of the tire 10 is a bias structure, but the present invention is not limited to this structure, and the internal structure may be a radial structure. In this case, the tire diameter of the carcass 16 One or a plurality of belts or the like that generate an effect for suppressing the expansion in the tire radial direction may be disposed on the outer side in the direction.

  In the first embodiment, the central vibration absorbing rubber layer 32 and the side vibration absorbing rubber layer 34 are separated from each other. However, the present invention is not limited to this configuration. The side vibration absorbing rubber layer 34 may be composed of a single (continuous) vibration absorbing rubber layer integrally formed. In this case, since the central vibration absorbing rubber layer 32 and the side vibration absorbing rubber layer 34 are continuous in the range from the central area 40 to the side area 42 of the tread 22, the vibration absorbing effect can be enhanced as a whole. it can.

In the above-described embodiment, the low modulus rubber constituting the central vibration absorbing rubber layer 32 and the low modulus rubber constituting the side vibration absorbing rubber layer 34 are the same type of rubber material, but the present invention is limited to this configuration. The low modulus rubber constituting the central vibration absorbing rubber layer 32 and the low modulus rubber constituting the side vibration absorbing rubber layer 34 may be different rubber materials. In this case, the rubber material constituting the central vibration absorbing rubber layer disposed in the central area 40 according to the tire contact pressure distribution and specifications, and the side vibration absorbing rubber layer 34 disposed in the side area 42 are configured. Riding comfort performance can be improved by determining the rubber material to be used based on 100% modulus. In particular, from the viewpoint of tire contact pressure distribution, it is preferable to make the modulus of the side vibration absorbing rubber layer 34 smaller than the modulus of the central vibration absorbing rubber layer 32. By doing in this way, it becomes easy to obtain the effect of making the ground pressure distribution uniform. Even if the sum G2 of the maximum thickness of the side vibration absorbing rubber layer 34 is made larger than the sum G1 of the maximum thickness of the central vibration absorbing rubber layer 32, the effect of making the tire contact pressure distribution uniform can be easily obtained. For this reason, it is preferable to make the sum G2 of the maximum thickness of the side vibration absorbing rubber layer 34 larger than the sum G1 of the maximum thickness of the central vibration absorbing rubber layer 32. Further, by optimizing the relationship between the maximum thickness total G2 and modulus of the side vibration absorbing rubber layer 34 and the maximum thickness total G1 and modulus of the central vibration absorbing rubber layer 32, the contact pressure distribution of the tire can be improved. It becomes easier to obtain the uniform effect.
Furthermore, in the above-described embodiment, the low modulus rubber constituting the first central vibration absorbing rubber layer 32A and the low modulus rubber constituting the second central vibration absorbing rubber layer 32B are the same type of rubber material. The present invention is not limited to this configuration, and the low modulus rubber constituting the first central vibration absorbing rubber layer 32A and the low modulus rubber constituting the second central vibration absorbing rubber layer 32B are made of different types of rubber. It may be a material. In this case, fine adjustment of the contact pressure in the central area 40 of the tread 22 is further facilitated. Similarly, in the above-described embodiment, the low modulus rubber constituting the first side vibration absorbing rubber layer 34A and the low modulus rubber constituting the second side vibration absorbing rubber layer 34B are made of the same kind of rubber material. However, the present invention is not necessarily limited to this configuration, and the low modulus rubber constituting the first side vibration absorbing rubber layer 34A and the low modulus rubber constituting the second side vibration absorbing rubber layer 34B. May be made of different types of rubber materials. In this case, fine adjustment of the contact pressure in the side area 42 of the tread 22 is further facilitated.

  Moreover, in the above-mentioned embodiment, although the structure of the tire with a lug of this invention was applied to the pneumatic tire, this invention does not need to be limited to this structure, The structure of the tire with a lug of this invention is made into a solid tire. You may apply. In addition, as a solit tire, the wheel with rubber | gum which formed the tread on the outer periphery of the disk-shaped member (wheel), etc. are mentioned, for example. If the structure of the tire with lugs of the present invention is applied to the tread of the rubber wheel, the effects of the present invention can be obtained even with the rubber wheel.

  Further, in the above-described embodiment, as shown in FIG. 4, the unvulcanized tread rubber 24A, the first unvulcanized central vibration absorbing rubber 33A, and the first unvulcanized side vibration absorbing rubber 35A are integrally formed. The first unvulcanized tread member 23A is extruded and the unvulcanized tread rubber 24 is extruded to form the second unvulcanized tread member 23B. However, the present invention is not limited to this configuration. 6, the unvulcanized tread rubber 24 is extruded to form the first unvulcanized tread member 23A, the unvulcanized tread rubber 24A, the first unvulcanized central vibration absorbing rubber 33A, and The first unvulcanized side vibration absorbing rubber 35A is integrally extruded to form the second unvulcanized tread member 23B, and the bottom surface of the second unvulcanized tread member 23B is formed on the upper surface of the first unvulcanized tread member 23A. The two The upper surface of the unvulcanized tread member 23B by superimposing in close contact with the bottom surface of the third unvulcanized tread member 23C, it is possible to obtain the equivalent of a non-vulcanized tread 22A.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

[Test example]
In order to confirm the performance improvement effect of the present invention, one type of tire of a conventional example, one type of tire of a comparative example, and one type of tire of an example to which the present invention is applied are prepared, vibration measurement by a measuring instrument, And vibration ride performance was 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 (2008 edition, Japan Automobile Tire Association Standard). Used for testing. In addition, an Example is a tire of 1st Embodiment shown by FIG. 2, and a prior art example is a tire which does not arrange | position a vibration absorption rubber layer (namely, tire which remove | excluded the vibration absorption rubber layer from the Example), and a comparative example Is a tire in which one vibration absorbing rubber layer is arranged between the tread and the carcass (a tire in which the arrangement of the vibration absorbing rubber layer in the embodiment is changed). Table 1 shows the specifications of each 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)
In addition, the evaluation value of 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 levels of the comparative example and the example are significantly lower than those of the conventional example. Further, in the example in which the vibration absorbing rubber layer is disposed in the lug at two intervals in the tire radial direction, the result is better than the comparative example in which one vibration absorbing rubber layer is disposed between the tread and the carcass. Is obtained. Furthermore, it was confirmed that the vibration level (amplitude) of the comparative example and the example was lowered to a level not causing a problem as compared with the conventional example in the feeling evaluation by the occupant. In addition, in the feeling evaluation by the occupant, the result of the example is better than that of the comparative example. For this reason, it is more comfortable to ride two vibration absorbing rubber layers in the lug than the tread and carcass, with two vibration absorbing rubber layers spaced apart in the tire radial direction. It can be seen that good results are obtained.

It is a top view which shows the tread pattern of the tire of 1st Embodiment. FIG. 2 is a sectional view taken along line 2-2 of FIG. It is sectional drawing which shows the modification of the vibration absorption rubber used for the tire of 1st Embodiment. It is explanatory drawing for demonstrating the manufacturing method for manufacturing the tread part of the tire of 1st Embodiment. It is sectional drawing which shows the modification of the shape of the edge part of the tread of the tire of 1st Embodiment. It is explanatory drawing for demonstrating the modification of the manufacturing method for manufacturing the tread part of the tire of 1st Embodiment.

Explanation of symbols

10 tires (tires with lugs)
16 carcass 22 tread 23A first unvulcanized tread member (first unvulcanized tread member)
23B Second unvulcanized tread member (second unvulcanized tread member)
23C Third unvulcanized tread member (first unvulcanized tread member)
24 tread rubber 24A unvulcanized tread rubber 26 lug 27 tread (tread tread)
28 Lug groove 32 Center vibration absorbing rubber layer (vibration absorbing rubber layer)
32A First central vibration absorbing rubber layer (vibration absorbing rubber layer)
32B Second central vibration absorbing rubber layer (vibration absorbing rubber layer)
33A First unvulcanized central vibration absorbing rubber (unvulcanized vibration absorbing rubber)
33B Second unvulcanized central vibration absorbing rubber (unvulcanized vibration absorbing rubber)
34 Side vibration absorbing rubber layer (vibration absorbing rubber layer)
34A First side vibration absorbing rubber layer (vibration absorbing rubber layer)
34B Second side vibration absorbing rubber layer (vibration absorbing rubber layer)
35A First unvulcanized side vibration absorbing rubber (unvulcanized vibration absorbing rubber)
35B Second unvulcanized side vibration absorbing rubber (unvulcanized vibration absorbing rubber)
40 Central area 42 Side area CL Equatorial plane (tire equatorial plane)
G1 Total maximum thickness of the center vibration absorbing rubber layer
G2 Total of maximum thickness of side vibration absorbing rubber D1 Groove depth of lug groove D2 Groove depth of lug groove R1 First radius of curvature (curvature radius)
R2 Second radius of curvature (curvature radius)
TW tread width

Claims (6)

In the cross section in the tire width direction, a tread whose radius of curvature of the tread surface contacting the road surface is smaller in the side area continuous from the central area than the central area straddling the tire equator plane,
A plurality of lugs formed on the tread and extending from a central portion of the tread in a tire width direction toward a side portion;
A plurality of vibration-absorbing rubbers having a modulus lower than that of the tread rubber that is provided in the lug corresponding to the central area and the lugs corresponding to the side areas in the radial direction of the tire and spaced apart in the tire radial direction. Layers,
A tire with lugs.   The lug-equipped tire according to claim 1, wherein a central area of the tread satisfies a range of 40 to 60% of a tread width.   The tire with a lug according to claim 1 or 2, wherein a 100% modulus of the vibration absorbing rubber layer satisfies a range of 30 to 70% of a 100% modulus of the tread rubber.   The sum of the maximum thicknesses of the vibration absorbing rubber layers inside the lugs corresponding to the side areas is 5 to 20% of the groove depth of the lug grooves between the lugs adjacent in the tire circumferential direction in the tread hump portion. The sum of the maximum thicknesses of the vibration-absorbing rubber layers inside the lugs corresponding to the central area satisfies the range of 10 to 40% of the groove depth on the tire equatorial plane of the lug grooves. The tire with a lug according to any one of claims 1 to 3.   5. The vibration absorbing rubber layer inside the lug corresponding to the central area and the vibration absorbing rubber layer inside the lug corresponding to the side area are continuous. 6. A tire with a lug as described in 1. In the manufacturing method of the tire with a lug of any one of Claims 1-5,
The unvulcanized tread rubber and the unvulcanized vibration absorbing rubber are integrally extruded so that the vibration absorbing rubber layer is disposed in the center area of the tread and the side area of the tread, and the belt-shaped first A step of forming a plurality of unvulcanized tread members;
Extruding the unvulcanized tread rubber to form a strip-shaped second unvulcanized tread member;
The first unvulcanized tread member and the second so that the unvulcanized vibration absorbing rubber is disposed between the first unvulcanized tread member and the second unvulcanized tread member. A step of stacking the unvulcanized tread member of
The manufacturing method of the tire with a lug provided with.

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