JP2005289315A - Tire for agricultural machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire for an agricultural machine improved in vibrational ride comfort, especially vibrational ride comfort at the of travelling on a fine road without decreasing traction performance. <P>SOLUTION: This tire 10 for the agricultural machine is provided with a vibration absorbing rubber layer 24 absorbing vibration in at least a part of the inner side of the central part Scn in the tire radial direction. The central area Acn including the central part Scn is set in the range of 40%-60% of the length of a tread width in the tread width direction while straddling a tire equator line CL. A radius of curvature R<SB>1</SB>, which is the radius of curvature of the central part Scn is two times as much as a tire radius H<SB>0</SB>and more. Moreover, a radius of curvature R<SB>2</SB>, which is the radius of curvature of a shoulder part Ssh, is smaller than the radius of curvature R<SB>1</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a plurality of lugs including a central portion located closer to the tire equator line and a shoulder portion located on the outer side in the tread width direction away from the tire equator line than the central portion are provided in the tread portion. More particularly, the present invention relates to a tire for an agricultural machine that further improves vibration ride comfort when traveling on a good road such as a paved road.

  Conventionally, in agricultural machinery tires in which a plurality of lugs are formed in the tread portion, in order to ensure the traction performance, which is the most basic performance, it is generally performed to set the tread width, that is, the lug width as wide as possible. I have been. For example, in a conventional agricultural machine tire, a tread width has been set wider than a tire width which is a width between sidewalls.

  In such conventional tires for agricultural machinery, the traction performance and the vibration ride comfort are basically in a trade-off relationship, and in order to ensure the predetermined traction performance, the vibration ride comfort must be sacrificed. There was a problem of not getting.

  Therefore, various methods for improving the vibration ride comfort of such agricultural machine tires have been proposed and realized. For example, as a technique for improving vibration ride comfort, it is known to form each lug so as to overlap with other lugs in the tire circumferential direction or the tread width direction.

  There is also known a technique for improving the vibration ride comfort by reducing the contact pressure of the shoulder portion of the lug (for example, Patent Document 1). FIG. 5 is a partial cross-sectional view in the tread width direction of a conventional agricultural machine tire employing such a method.

  As shown in the figure, the conventional agricultural machine tire 20 is provided with a plurality of lugs 21 in the tread portion 22 along the circumferential direction of the agricultural machine tire 20. Although not shown in the figure, a lug having a symmetrical shape with the lug 21 is disposed on the opposite side of the tire equator line CL along the circumferential direction of the agricultural machine tire 20. A plurality are provided at positions different from the positions in the circumferential direction.

  A frame of the agricultural machine tire 20 is formed on the inner side of the tread portion 22 in the tire radial direction so as to withstand the load of the agricultural machine to which the agricultural machine tire 20 is attached and the filled air pressure. A carcass ply 23 for maintaining the structure is located.

Moreover, as shown in the figure, the lugs 21 have different curvature radii R ₁ and R ₂ of the ground contact surface between the central portion Scn and the shoulder portion Ssh. Specifically, the curvature radius of curvature R ₁ is the radius of the ground plane of the central portion Scn is set to more than 2 times the tire radius H _0. In agricultural machines for tire 20, the radius of curvature R ₁ is set to be infinite, that is a straight line. On the other hand, the radius of curvature R ₂ is the radius of curvature of the ground contact surface of shoulder portion Ssh is set to a value smaller than the radius of curvature R _1.

  Further, in the agricultural machine tire 20, the central region Acn including the central portion Scn is set over a region of 40% to 60% of the tread width TW including the tire equator line CL. The tread width TW refers to the lug outer end 21e of the lug 21 shown in the same figure and the outer end (not shown) of another lug located on the opposite side of the tire equator line CL in the tread width direction cross section. Is the distance. Further, the center region Acn is specifically formed by the center portion Scn of the lug 21 and the center portion Scn (not shown) of another lug located on the opposite side of the tire equator line CL.

Further, in the agricultural machine tire 20, the drop height H ₂ that is the distance between the ground contact surface of the central portion Scn and the position of the lug outer end portion 21 e in the tire radial direction is set with the curvature radii R ₁ and R ₂ described above. While maintaining the range, it is set to 6% to 10% of the tread width TW. Further, the center groove depth H ₁ is a distance between the tread portion 22 and the ground contact surface with the road surface of the central portion Scn on the tire equator line CL.

According to the lug 21 formed in the agricultural machine tire 20 shown in FIG. 5, the contact pressure of the shoulder portion Ssh is reduced, and the vibration ride comfort can be improved.
JP 2003-146019 A (2nd page, FIG. 1)

  By the way, in recent years, opportunities for agricultural machines such as agricultural tractors to travel on good roads such as paved roads have increased, and attention has been paid to the vibration riding comfort of agricultural machine tires, which has not attracted much attention in the past. Yes.

  As described above, a method to improve the vibration ride comfort of agricultural machinery tires has been proposed and realized, but with such a method, the vibration ride comfort that 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, tires for agricultural machinery have been provided in which the tire width and tread width are substantially the same, and the vibration riding comfort is improved without significantly reducing the traction performance. In the market, it has been strongly desired to provide tires for agricultural machinery with further improved vibration ride comfort.

  Accordingly, the present invention has been made in view of the above-described problems, and the tire for agricultural machinery has further improved vibration ride comfort, particularly vibration ride comfort during running on a good road, without reducing traction performance. The purpose is to provide.

  As described above, the wider the tread width (lug width), the more the traction performance can be improved. However, by increasing the tread width, the vibration riding comfort will not decrease. Are in a trade-off relationship.

  Therefore, the inventors examined a method for maintaining and improving both the traction performance and the vibration ride comfort in consideration of such a trade-off relationship.

  Generally, a decrease in the vibration ride comfort of an agricultural machine (vehicle) such as an agricultural tractor 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, in the case of a bias-ply tire, the central region straddling the tire equator line, and the shoulder portion of the lug located on the outer side in the tread width direction farther from the tire equator line than the central region, (1) End (lag outer end 21e), (2) central region (central region Acn), and (3) end of lug shoulder provided on the opposite side of the tire equator (lug outer end 21e) The grounding pressure at is higher than the other parts, that is, the grounding pressure distribution is “W” -shaped.

  The inventors pay attention to the fact that the pattern pitch component resulting from this “W” -shaped contact pressure distribution causes vibration due to rolling of the tire for agricultural machinery, specifically, radial force variation (RFV). did.

Therefore, the present invention has the following features. First, the first feature of the present invention is that a central portion (central portion Scn) located near the tire equator line (tire equator line CL) and a tread width direction outer side farther from the tire equator line than the central portion. A lug (lug 21) composed of a shoulder portion (shoulder portion Ssh) positioned is a plurality of agricultural machine tires (for example, agricultural machine tires 10) provided in a tread portion (tread portion 22), A vibration-absorbing rubber layer that absorbs vibration (for example, the vibration-absorbing rubber layer 24) is provided on at least a part of the inner portion in the tire radial direction of the central portion, and a central region (central region Acn) including the central portion has a tread width In the direction, it is set over a length of 40% to 60% of the tread width which is the width of the tread portion, straddling the tire equator line, and the curvature of the ground contact surface where the central portion contacts the road surface. First radius of curvature is the radius (radius of curvature R ₁₎ is, the not less than 2 times the agricultural machine tire radius (tire radius H _0), and the radius of curvature of the ground surface on which the shoulder portion is contact with the road surface The second curvature radius (curvature radius R ₂ ) is smaller than the first curvature radius.

  According to this feature, since the vibration absorbing rubber layer that absorbs vibration is provided in the tire radial direction inner side of the central portion of the lug, the ground pressure in the central region where the ground pressure becomes higher than other portions can be reduced. it can.

  As a result, the contact pressure distribution in the tread portion can be made more uniform than in conventional agricultural machine tires, and the pattern pitch component, more specifically, radial force variation (RFV) is reduced.

  In addition, according to this feature, the radius of curvature of the shoulder contact surface of the lug (second curvature radius) is smaller than the radius of curvature of the ground contact surface of the central portion of the lug (first curvature radius). The outer end portion (the lug outer end portion 21e) is located on the inner side in the tire radial direction than the other portion of the shoulder portion. For this reason, the contact pressure at the outer end portion is reduced, and the contact pressure distribution in the tread portion can be made uniform.

  In other words, according to such a feature, the “W” -shaped contact pressure distribution is corrected by the vibration absorbing rubber layer and the shape of the shoulder portion of the lug, so that the vibration ride comfort is not reduced without reducing the traction performance. In particular, it is possible to provide an agricultural machine tire that is further improved in vibration ride comfort when traveling on a good road.

  The second feature of the present invention is that, in the first feature of the present invention, 100% modulus of the vibration-absorbing rubber layer is 70% or less of the rubber forming the tread portion including the lug. To do.

  According to such a feature, since the 100% modulus of the vibration absorbing rubber layer is 70% or less of the rubber forming the tread portion including the lug, the contact pressure in the central region can be effectively reduced.

According to a third feature of the present invention, in the first or second feature of the present invention, a height (rubber layer height H ₃ ) of the vibration absorbing rubber layer in the tire radial direction is the center on the tire equator line. The gist is that it is 10% to 40% of the center groove depth (center groove depth H ₁ ) which is the distance between the ground contact surface of the portion and the tread portion.

According to this feature, since the height of the vibration absorbing rubber layer in the tire radial direction is 10% to 40% of the center groove depth (center groove depth H ₁ ), the contact pressure in the center region is reduced. In addition, the contact pressure of the tread portion can be made more uniform.

  ADVANTAGE OF THE INVENTION According to this invention, the tire for agricultural machines which further improved the vibration riding comfort, especially the vibration riding comfort at the time of driving | running | working on a good road can be provided, without reducing traction performance.

(Configuration of agricultural machine tire according to the present embodiment)
Next, an example of an embodiment of an agricultural machine tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  FIG. 1 shows a partial cross-sectional view in the tread width direction of an agricultural machine tire according to the present embodiment. Moreover, FIG. 2 has shown the partial plane expanded view of the tread of the tire for agricultural machines which concerns on this embodiment.

  As shown in FIGS. 1 and 2, the agricultural machine tire 10 according to this embodiment includes a plurality of lugs 21 in the tread portion 22 along the circumferential direction of the agricultural machine tire 10. The agricultural machine tire 10 shown in FIGS. 1 and 2 has substantially the same shape as the conventional agricultural machine tire 20 shown in FIG. 5 in appearance.

  Further, the shape of the lug 21 on the tread surface is not limited to the shape as shown in FIG. 2, for example, an angle formed by the stepping side or kicking side surface of the lug 21 and the tire equator line CL. Is not limited to the angle shown in the figure, and can be changed as appropriate.

  As shown in FIG. 1, the frame of the agricultural machine tire 10 is formed on the inner side in the tire radial direction of the tread portion 22, and can withstand the load of the agricultural machine on which the agricultural machine tire 10 is mounted and the filled air pressure. The carcass ply 23 for maintaining the structure of the agricultural machine tire 10 is located.

In addition, the lug 21 has different curvature radii R ₁ and R ₂ of the ground contact surface in the central portion Scn and the shoulder portion Ssh. Specifically, the curvature radius of curvature R ₁ is the radius of the ground plane of the central portion Scn is set to more than 2 times the tire radius H _0. In agricultural machines for tire 10, the radius of curvature R ₁ is set to be infinite, that is a straight line. On the other hand, the radius of curvature R ₂ is the radius of curvature of the ground contact surface of shoulder portion Ssh is set to a value smaller than the radius of curvature R _1.

The curvature radii R ₁ and R ₂ are the curvatures of the ground contact surface (central part Scn, shoulder part Ssh) measured after filling the prescribed pneumatic pressure to the agricultural machine tire 10 assembled to the prescribed rim wheel and reporting the prescribed time. This is the radius.

  In the agricultural machine tire 10, the central region Acn including the central portion Scn is set over a region of 40% to 60% of the tread width TW including the tire equator line CL. As shown in FIG. 2, the tread width TW is the distance between the lug outer end 21ea of the lug 21A and the lug outer end 21eb of the lug 21B located on the opposite side of the tire equator line CL. Further, the central region Acn is formed by the central portion Scn of the lug 21A and the central portion Scn of the lug 21B in the tread width direction.

Furthermore, in the agricultural machine tire 10, as shown in FIG. 1, the drop height H ₂ that is the distance between the ground contact surface of the central portion Scn and the position of the lug outer end portion 21 e in the tire radial direction is a curvature radius R _1. while maintaining the set range mentioned above the _{R 2,} it is set to 6% to 10% of the tread width TW. Further, the center groove depth H ₁ is the ground plane of the road surface of the central portion Scn on the tire equator line CL, the distance between the tread portion 22, the agricultural machines tire 10 is set to 42mm.

  Further, as shown in FIG. 1, the agricultural machine tire 10 includes a vibration absorbing rubber layer 24 that absorbs vibration at least at a part inside the tire radial direction of the central portion Scn. Specifically, the vibration absorbing rubber layer 24 is provided at the inner side in the tire radial direction of the central portion Scn of the lug 21 and at the outer side in the tire radial direction than the carcass ply 23. In addition, when the agricultural machine tire 10 includes a belt layer (breaker) that reinforces the carcass ply 23, the vibration absorbing rubber layer 24 may be provided outside the belt layer in the tire radial direction.

Further, as shown in FIG. 1, the vibration absorbing rubber layer 24 has a substantially trapezoidal shape in the cross section in the tread width direction. Further, the rubber layer height _{H 3} of the vibration absorbing rubber layer 24 is set to 10% to 40% of the center groove depth _{H 1.} In the agricultural machine tire 10, the rubber layer height H ₃ is 8.0 mm, which is set to 19% of the center groove depth H ₁ (42 mm).

That is, the rubber layer height H _3, if more than 40% of the center groove depth H _1, displacement in the tire radial direction of the vibration absorbing rubber layer 24 is increased, the ground contact pressure in the central region Acn drops greater For this reason, the effect of equalizing the ground pressure is limited.

  Further, as shown in FIG. 2, the vibration absorbing rubber layer 24 is located in the central region Acn across the tire equator line CL. In the agricultural machine tire 10, the rubber layer width GW of the vibration absorbing rubber layer 24. Is set to 120 mm.

  Further, the 100% modulus of the vibration absorbing rubber layer 24 is set to be 70% or less of the rubber forming the tread portion 22 including the lug 21. Specifically, the 100% modulus of the rubber forming the tread portion 22 including the lugs 21 is 6.0 MPa. On the other hand, the 100% modulus of the vibration absorbing rubber layer 24 is set to 3.0 MPa, that is, 50% of the rubber forming the tread portion 22.

  That is, when the 100% modulus of the vibration absorbing rubber layer 24 exceeds 70% of the rubber forming the tread portion 22 including the lugs 21, the displacement amount of the vibration absorbing rubber layer 24 in the tire radial direction becomes small, and the central region Acn The effect of lowering the contact pressure at is limited.

(Comparison evaluation)
Next, a comparative evaluation test conducted on the agricultural machine tire 10 according to the present embodiment (hereinafter referred to as an example) and the agricultural machine tire 20 according to the conventional example illustrated in FIG. 5 (hereinafter referred to as a conventional example). The method and the results will be described.

(1) Test method Table 1 has shown the item of the tire for agricultural machines which concerns on the Example used for comparative evaluation, and a prior art example.

  As shown in Table 1, the example (agricultural machine tire 10) and the conventional example (agricultural machine tire 20) have substantially the same shape in appearance.

  In a test related to comparative evaluation, vibration (amplitude level) was measured using a measuring instrument. Furthermore, it boarded the agricultural machine (agricultural tractor) with which the agricultural machine tire which concerns on an Example and a prior art example was mounted | worn, and the feeling evaluation by the passenger | crew was performed.

  The test conditions for the comparative evaluation are as follows.

・ Used tire size: 13.6-26 4PR T13H
・ Travel type: Concrete paved road ・ Travel speed: 16km / h (straight running)
・ Agricultural machine type: Agricultural tractor (41 hp, 2 wheel drive)
(2) Test results Table 2 shows the results of the tests related to the comparative evaluation described above.

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

(Action / Effect)
According to the agricultural machine tire 10 according to the present embodiment described above, since the vibration absorbing rubber layer 24 that absorbs vibration is provided on the inner side in the tire radial direction of the central portion Scn of the lug 21, the grounding is performed from other portions. The ground pressure in the central region Acn where the pressure increases can be reduced.

  As a result, the contact pressure distribution in the tread portion 22 can be made more uniform than in the conventional agricultural machine tire 20, and the pattern pitch component, more specifically, radial force variation (RFV) is reduced.

Further, according to the agricultural machine tire 10, the radius of curvature R ₂ of the shoulder portion Ssh ground plane of the lug 21, which is smaller than the radius of curvature R ₁ of the center portion Scn grounding surface of the lug 21, the lug outer end section 21e And, it will be located in the tire radial direction inner side rather than the other part of shoulder part Ssh. For this reason, the contact pressure at the lug outer end portion 21e is reduced, and the contact pressure distribution in the tread portion 22 can be made uniform.

  That is, according to the agricultural machine tire 10, the contact pressure distribution is made uniform by the vibration absorbing rubber layer 24 and the shape of the shoulder portion Ssh of the lug 21. Thus, it is possible to provide a tire for agricultural machinery having improved characteristics, particularly vibration ride comfort when traveling on a good road.

(Example of change)
As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the present invention can be modified as follows. 3 and 4 show partial cross-sectional views in the tread width direction of the agricultural machine tire 11 and the agricultural machine tire 12 according to the modified example of the present invention, respectively.

  As illustrated in FIG. 3, the agricultural machine tire 11 includes a vibration absorbing rubber layer 24 ′ that absorbs vibration at least at a part inside the tire radial direction of the central portion Scn.

  The vibration absorbing rubber layer 24 ′ has a different shape in the cross section in the tread width direction compared to the vibration absorbing rubber layer 24 provided in the agricultural machine tire 10 described above. Specifically, the vibration absorbing rubber layer 24 ′ has a shape such that its height gradually decreases as it approaches the end in the width direction of the vibration absorbing rubber layer 24 ′.

  Further, as shown in FIG. 4, the agricultural machine tire 12 includes a vibration absorbing rubber layer 24 ″ that absorbs vibration at least at a part inside the tire radial direction of the central portion Scn.

  The vibration absorbing rubber layer 24 ″ also has a different shape in the cross section in the tread width direction as compared with the vibration absorbing rubber layer 24 provided in the agricultural machine tire 10 described above. Specifically, the vibration absorbing rubber layer 24 is different. "Has a substantially rectangular shape in the cross section in the tread width direction.

  The agricultural machine tires 11 and 12 provided with the vibration absorbing rubber layers 24 ′ and 24 ″ having the shapes shown in FIGS. 3 and 4 can also exhibit the same effects as the agricultural machine tire 10 described above. The vibration absorbing rubber layer may have a substantially rectangular shape such as the vibration absorbing rubber layer 24 ″, but is preferably shaped like the vibration absorbing rubber layers 24 and 24 ′.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is a partial cross section figure in the tread width direction of the tire for agricultural machines concerning the embodiment of the present invention. It is a partial plane development view of the tread of the agricultural machine tire according to the embodiment of the present invention. It is a partial cross section figure in the tread width direction of the tire for agricultural machines concerning the example of change of the present invention. It is a partial cross section figure in the tread width direction of the tire for agricultural machines concerning the example of change of the present invention. It is a partial cross section figure in the tread width direction of the conventional tire for agricultural machines.

Explanation of symbols

10-12, 20 ... agricultural machinery tires, 21, 21A, 21B ... lugs, 21e, 21ea, 21eb ... lug outer end, 22 ... tread portion, 23 ... carcass ply, 24, 24 ', 24 "... vibration absorption rubber layer, Acn ... central region, CL ... tire equator line, GW ... rubber layer width, H 0 _... tire radius, H 1 _... center groove depth, H 2 _... fall height, H 3 _... rubber layer height, _{R 1} , R ₂ ... radius of curvature, Scn ... center, Ssh ... shoulder, TW ... tread width

Claims (3)

Agricultural machinery in which a plurality of lugs including a central portion located closer to the tire equator line and a shoulder portion located on the outer side in the tread width direction away from the tire equator line than the central portion are provided in the tread portion Tire,
A vibration absorbing rubber layer that absorbs vibration is provided in at least a part of the inner side in the tire radial direction of the central portion,
A central region including the central portion is set over a length of 40% to 60% of the tread width, which is the width of the tread portion, across the tire equator line in the tread width direction.
The first radius of curvature, which is the radius of curvature of the ground contact surface where the center portion contacts the road surface, is at least twice the radius of the tire for agricultural machinery, and the radius of curvature of the ground contact surface where the shoulder portion contacts the road surface. A tire for agricultural machinery, wherein the second curvature radius is smaller than the first curvature radius.   2. The agricultural machine tire according to claim 1, wherein a 100% modulus of the vibration absorbing rubber layer is 70% or less of rubber forming the tread portion including the lugs.   The height of the vibration-absorbing rubber layer in the tire radial direction is 10% to 40% of a center groove depth, which is a distance between the ground contact surface of the center portion and the tread portion on the tire equator line. The agricultural machine tire according to claim 1 or 2.

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