JP2007015493A - Pneumatic type cushion tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic type cushion tire hardly generating heat generation failure without impairing other performances. <P>SOLUTION: The pneumatic type cushion tire 10 has a tread rubber layer 12; and a base rubber layer contacted with a rim at an inner side in a radial direction of the tread rubber layer 12. A side groove 22 extending from a tire side part 20 toward a tire equator plane CL is arranged on the tread rubber layer 12. Thereby, since heat release is promoted by the side groove 22, heat generation is suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic cushion tire that is optimal for use in industrial vehicles.

  Pneumatic cushion tires are used in various applications (see, for example, Patent Documents 1 to 4). This pneumatic cushion tire is often composed of an inner rubber layer (base rubber layer) that comes into contact with the tire rim and an outer rubber layer positioned on the outer side in the tire radial direction.

  In this pneumatic cushion tire, unlike a pneumatic tire, there is a problem that failure due to heat generation (heat generation failure) is likely to occur under severe use conditions. The severe use conditions that cause a heat generation failure are severe use conditions such as heavy load, high speed, continuous operation, start / brake, excessive SF input, and the like.

  The following measures are conceivable as measures for preventing such a heat generation failure.

  A first countermeasure is to dispose rubber with good heat resistance in the outer rubber layer. The rubber having good heat resistance is, for example, a rubber having a high Mod (M50: 1.2 or more) and a low tan δ (0.21 or less). However, although the heat generation reduction effect is great, since the tread rubber has a heat generation-oriented type blending design, there arises another problem that a contradiction such as a decrease in wear resistance occurs.

  As a second countermeasure, it is conceivable that the outer rubber layer has a two-layer structure of CAP / BASE, and rubber having good heat resistance is arranged on the BASE, that is, functional separation is performed by a multilayer divided structure. However, although it is possible to supplement the contradiction quality by separating the functions by CAP / BASE, the heat generation reduction effect is small as compared with the first countermeasure. Furthermore, since it has two layers, it is disadvantageous to impair productivity.

As a third countermeasure, it is conceivable to mix a rubber having good heat resistance with respect to the short fiber mixed rubber of the inner rubber layer. However, although the productivity is greatly reduced by selecting the rubber material type, there is a problem that the effect of reducing the generated heat is small.
Japanese Patent Laying-Open No. 2005-67513 JP 2003-72315 A JP 2002-254902 A Japanese Patent Laid-Open No. 7-232508

  In view of the above facts, an object of the present invention is to provide a pneumatic cushion tire in which a heat generation failure is hardly caused without impairing other performance.

  The inventor has paid attention to the fact that heat is accumulated inside the tire due to energy loss due to strain during rolling of the tire. Unlike pneumatic tires, pneumatic cushion tires, in which the rate of change in heat rise and maximum value are determined by the conditions of use (load, speed, operating rate, etc.), tire structure, and materials, are all rubber inside the tire. Because it is composed of, we also paid attention to the disadvantage in terms of heat dissipation.

  Furthermore, the failure mechanism due to heat generation was also examined. As shown in FIG. 6, if the temperature increase due to heat storage is larger than the temperature decrease due to heat dissipation, the tire temperature gradually rises, and when the temperature rises to a temperature at which the rubber is destroyed, heat separation occurs. I found out what happened. Further, as shown in FIG. 7, it has also been found that this is likely to occur when traveling and stopping are repeated.

  Therefore, as a result of intensive studies, the present inventor has come up with the idea that what has been dealt with by rubber compounding design can be made by shape design, and further studies have been made to complete the present invention.

  The invention according to claim 1 is a pneumatic cushion tire having at least one tread rubber layer and a base rubber layer in contact with the rim at a radially inner side of the tread rubber layer, wherein the tread rubber layer includes a tire. A side groove extending from the side portion toward the tire equatorial plane is arranged.

  In the first aspect of the invention, the side groove extending from the tire side portion toward the tire equatorial plane is thus arranged in the tread rubber layer. Thereby, since heat dissipation is promoted by the side grooves, heat generation is suppressed, and heat generation durability is improved. Further, by forming the side grooves, the volume of rubber can be reduced to reduce the total amount of hysteresis loss, so that the tire rolling resistance is reduced. Further, the arrangement of the side grooves does not impair other performance such as wear resistance and productivity.

  Therefore, a pneumatic cushion tire that does not easily cause a heat generation failure without impairing other performances is realized. Moreover, riding comfort improves by formation of a side groove.

  The invention according to claim 2 is characterized in that the side grooves are arranged on both sides of the tire equatorial plane.

  Thereby, the heat dissipation effect can be improved on both sides of the tire equatorial plane.

  The invention according to claim 3 is characterized in that the side grooves are formed continuously or intermittently along the tire circumferential direction.

  Thereby, the improvement of a heat dissipation effect and the reduction | decrease of the volume of rubber | gum can be made more remarkable.

  The improvement of heat dissipation effect and the reduction of rubber volume are most effective when the side grooves are continuously arranged in the circumferential direction, but almost the same effect can be expected even if they are intermittently arranged in the circumferential direction. . Moreover, you may arrange | position in the circumferential direction in zigzag form.

  The invention according to claim 4 is characterized in that the side groove extends parallel to the tire axial direction.

  Thus, by arranging the side grooves in parallel with the tire axial direction, the vulcanized tire can be easily taken out from the mold, and manufacturing defects can be suppressed.

  According to a fifth aspect of the present invention, the height from the base line of the rim to the center of the side groove in the tire side portion is 0.35 to 0.8 times the tire cross-section height, and the tire in the side groove The radial width is 0.03 to 0.35 times the tire cross-sectional height, and the depth of the side groove in the tire axial direction is 0.15 to 0.7 times the tire cross-sectional width. And

  If the height from the base line of the rim to the center of the side groove at the tire side portion is smaller than 0.35 times the tire cross-section height, the side groove is formed in the base layer having a high elastic modulus. This base layer is usually a part where the heat generation level is not high. For this reason, there are few heat dissipation effects obtained.

  On the other hand, when the height from the base line of the rim to the center of the tire side portion of the side groove is greater than 0.8 times the tire cross-section height, the side groove is formed in the crown portion where the movement is large. If a side groove is formed in the crown portion, durability problems are likely to occur due to deterioration of rolling resistance, occurrence of buttress cracks, and the like.

  The height from the rim base line to the center of the tire side of the side groove is 0.35 to 0.8 times the tire cross-section height, so the side groove is located in a region where heat can easily accumulate inside the tire. Is done.

  Moreover, if the width of the side groove in the tire radial direction is shorter than 0.03 times the tire cross-sectional height, the obtained heat dissipation effect is small. On the other hand, if the width of the side groove in the tire radial direction is longer than 0.35 times the tire cross-sectional height, problems are likely to occur in durability and steering stability.

  Moreover, if the depth of the side groove in the tire axial direction is shallower than 0.15 times the tire one-side cross-sectional width, the obtained heat dissipation effect is small. On the other hand, if the depth of the side groove in the tire axial direction is deeper than 0.7 times the tire side cross-sectional width, problems are likely to occur in durability and steering stability.

  According to the fifth aspect of the present invention, a sufficient heat dissipation effect can be obtained, and problems of durability and steering stability are unlikely to occur.

  The invention according to claim 6 is characterized in that the shape of the tip portion of the side groove on the tire equatorial plane side is a flask shape.

  As a result, the strain concentration at the bottom of the side groove can be relaxed, and the problem of durability hardly occurs.

  In the invention according to claim 7, in the side groove, the ratio of the widest width seen in the tire radial direction in the flask shape and the width seen in the tire radial direction at the tire side portion is 1.03 to 3. It is characterized by being in the range of 1.4.

  In the invention according to claim 7, in this way, by increasing the groove width on the tip side (flask shape) of the side groove than the groove width on the tire surface side of the side groove, strain concentration at the groove tip portion is reduced. Can be relaxed.

  If the above ratio is smaller than 1.03, the effect of relaxing the strain concentration is not so much achieved.

  Further, if the above ratio is larger than 1.4, a tire manufacturing problem is likely to occur. For example, when vulcanizing with the upper / lower mold mold, when removing the tire from the hook (mold) after vulcanization, the portion of the hook inserted in the side groove is difficult to come off, and there is no rubber chip when removing. It is likely to occur.

  According to the first aspect of the present invention, it is possible to realize a pneumatic cushion tire that is less likely to cause a heat generation failure without impairing other performance.

  According to the invention described in claim 2, it is possible to increase the heat dissipation effect on both sides of the tire equatorial plane.

  According to the invention described in claim 3, the improvement of the heat dissipation effect and the reduction of the volume of rubber can be made more remarkable.

  According to the invention described in claim 4, it is possible to suppress the manufacturing failure of the tire.

  According to the fifth aspect of the present invention, a sufficient heat dissipation effect can be obtained, and problems of durability and steering stability are unlikely to occur.

  According to the sixth aspect of the present invention, the strain concentration at the groove bottom of the side groove can be alleviated, and the problem of durability hardly occurs.

  According to the seventh aspect of the present invention, strain concentration at the groove tip can be reduced.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals, and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. As shown in FIG. 1, the pneumatic cushion tire 10 according to the present embodiment includes a tread rubber layer 12 and a base rubber layer 14 that comes into contact with the rim on the radially inner side of the tread rubber layer 12.

  The tread rubber layer 12 includes a middle rubber layer 16 joined to the base rubber layer 14 and a top rubber layer 18 located on the radially outermost side.

  In the middle rubber layer 16, side grooves 22 extending from the tire side portion 20 toward the tire equatorial plane CL are disposed on both sides of the tire equatorial plane CL. The side grooves 22 are formed intermittently along the tire circumferential direction and extend parallel to the tire axial direction Z (see FIG. 3).

  As shown in FIG. 2, the height b from the base line BL of the rim to the center of the side groove 22 in the tire side portion 20 is 0.35 to 0.8 times the tire cross-section height a. The width d in the tire radial direction of the side groove 22 is 0.03 to 0.35 times the tire sectional height a, and the depth c in the tire axial direction of the side groove 22 is 0.15 of the tire one-side sectional width g. It is set to 0.7 times.

  The shape of the tip (groove bottom) 22T of the side groove 22 on the tire equatorial plane side is a flask shape. And in the side groove | channel 22, ratio e / d of the widest width e seen in the tire radial direction in the front-end | tip part 22T and the width d seen in the tire radial direction in the tire side part 20 is 1.03-1. The range is 4.

  The tip portion 22T is, for example, spherical. The depth f of the tip portion 22T is set to a depth that moderately relaxes the strain concentration generated in the rubber portion forming the tip portion 22T.

  In the present embodiment, the side grooves 22 extending from the tire side portion 20 toward the tire equatorial plane CL are thus arranged in the middle rubber layer 16. Thereby, heat dissipation is promoted by the side grooves 22 and heat generation is suppressed, so that heat generation durability is improved. Further, since the side groove 22 is formed, the volume of rubber can be reduced and the total amount of hysteresis loss can be reduced, so that the rolling resistance of the tire is reduced. Further, the formation of the side grooves 22 improves riding comfort. The arrangement of the side grooves 22 does not impair other performance such as wear resistance and productivity. Therefore, the pneumatic cushion tire 10 that does not easily cause a heat generation failure without impairing other performances is realized.

  A plurality of side grooves 22 are formed intermittently along the tire circumferential direction, and the side grooves 22 are formed not only on one side of the tire equatorial plane CL but also on both sides. As a result, the heat dissipation effect can be further increased, and the reduction in the rubber volume can be made more remarkable.

  Further, since the side grooves 22 are arranged in parallel with the tire axial direction, the vulcanized tire can be easily taken out from the mold, and manufacturing defects can be suppressed.

  In addition, since the height b, width d, and depth c are in the above ranges, a sufficient heat dissipation effect can be obtained, and problems of durability and steering stability are unlikely to occur.

  In addition, since the shape of the tip portion 22T on the tire equatorial plane side of the side groove 22 is a flask shape, this can alleviate strain concentration at the groove bottom of the side groove 22, resulting in a problem of durability. Is more difficult to occur.

  Moreover, since the range of the ratio of the groove widths of the side grooves 22 between the front end portion 22T and the tire side portion 20 is defined as described above, strain concentration at the front end portion 22T can be reduced.

  In addition, as shown in FIG. 4, you may arrange | position the side groove | channel 22 to the circumferential direction in zigzag form. Thereby, the heat generation suppressing effect can be more remarkably achieved by further reducing the volume. Moreover, by making it zigzag, it becomes possible to avoid the distortion conditions due to the tire rigidity reduction.

[Second Embodiment]
Next, a second embodiment will be described. In the pneumatic cushion tire 30 according to the present embodiment, as compared with the first embodiment, instead of the intermittently formed side grooves 22 (see FIG. 3), as shown in FIG. The side grooves 32 formed in the tire are formed along the tire circumferential direction.

  Thereby, the effect of the improvement of a heat dissipation effect and the reduction | decrease of the volume of rubber | gum can be show | played more notably.

<Test example>
In order to confirm the effect of the present invention, the present inventor prepared the pneumatic cushion tire 10 of the first embodiment and the pneumatic cushion tire of the conventional example (hereinafter referred to as the tire of the conventional example). Performance was evaluated by running.

  As the pneumatic cushion tire 10, three types of tires having different tire sizes were prepared as shown in Table 1.

この３種類のタイヤとは、ＩＤＳ ７．００−１２ ＰＬ０１（以下、実施例１のタイヤという）、ＩＤＳ １８×７−８ ＰＬ０１（以下、実施例２のタイヤという）、及び、ＩＤＳ ５．００−８ ＰＬ０１（以下、実施例３のタイヤという）である。各タイヤにおけるａ〜ｇの値も表１に併せて示す。

These three types of tires are IDS 7.00-12 PL01 (hereinafter referred to as the tire of Example 1), IDS 18 × 7-8 PL01 (hereinafter referred to as the tire of Example 2), and IDS 5.00. -8 PL01 (hereinafter referred to as tire of Example 3). The values of a to g in each tire are also shown in Table 1.

  As a tire of a conventional example, a tire having a tire size of IDS 7.00-12 PL01 was prepared.

(Test on tire internal temperature characteristics)
The inventor attached the tire of Example 1 (rim type, 5.00 S) to an engine-type forklift for 2.5 tons. The mounting position is the front side, which is strict against heat generation. In addition, two types of tires were attached in a left-right pair so that the left and right sides (vehicle left and right) can be compared.

  And it carried out the field driving | running | working on condition of A company of Table 3 mentioned later, and measured the internal temperature of the tire for every fixed time, and calculated | required the maximum temperature. The measurement position of the internal temperature is a position 10 mm above the boundary between the base rubber layer 14 and the tread rubber layer 12 in the radial direction. In this test, a hole was drilled from the center of the tread surface and the temperature at this position was measured.

  Further, under the same conditions, the maximum temperature inside the tire was also measured for the conventional tire. Table 2 shows the measurement results. Table 2 shows that the lower the maximum temperature, the higher the heat generation suppression performance.

表２から判るように、実施例１のタイヤでは、従来例のタイヤに比べ、タイヤ内部の最高温度は３５℃も低かった。

As can be seen from Table 2, in the tire of Example 1, the maximum temperature inside the tire was 35 ° C. lower than that of the conventional tire.

(Test on rolling resistance characteristics)
In addition, the present inventor conducted a test to examine the rolling resistance indoors using another tire of Example 1 (that is, an unused tire of Example 1) and an unused conventional tire. The rim type is 5.00S × 12 (TB rim). The load was JATMA standard 100, and the traveling speed was 15 km / h.

  In the test for examining the rolling resistance, the evaluation for the tire of the conventional example was set to 100, and the index for relative evaluation was calculated for the tire of Example 1. The evaluation results are also shown in Table 2. Table 2 shows that the smaller the index, the lower the rolling resistance and the higher the heat generation suppression performance.

  As can be seen from Table 2, the rolling resistance of the tire of Example 1 is smaller than that of the conventional tire.

(Confirmation test for other defects)
In addition, in order to confirm that no other problems occur, the present inventor conducted field tests under transportation conditions of three companies as shown in Table 3.

この試験では、表３に示すように、Ａ社条件には実施例１のタイヤで、Ｂ社条件には実施例２のタイヤで、Ｃ社条件には実施例３のタイヤで、それぞれ試験を行った。車輌は全て２．５トン用のエンジン型フォークリフトとし、路面は全て舗装路とした。

In this test, as shown in Table 3, the tires of Example 1 were used for Company A conditions, the tires of Example 2 were used for Company B conditions, and the tires of Example 3 were used for Company C conditions. went. All vehicles were engine-type forklifts for 2.5 tons, and all road surfaces were paved roads.

  Table 3 shows the test conditions and the evaluation of the occurrence of defects. As can be seen from Table 3, no other defects occurred under any of the test conditions.

  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. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

It is radial direction sectional drawing of the pneumatic cushion tire which concerns on 1st Embodiment. It is a radial direction cross-sectional one side view of the pneumatic cushion tire concerning a 1st embodiment. 1 is a side view of a pneumatic cushion tire according to a first embodiment. It is a side view of the modification of the pneumatic cushion tire concerning a 1st embodiment. It is a side view of the pneumatic cushion tire concerning a 2nd embodiment. It is explanatory drawing which shows the mechanism in which the failure by heat_generation | fever arises. It is explanatory drawing which shows the example which a failure by heat_generation | fever produces by repetition of driving | running | working and a stop.

Explanation of symbols

10 Pneumatic cushion tire 12 Tread rubber layer 14 Base rubber layer 20 Tire side portion 22 Side groove 22T Front end portion (tire equatorial plane side front end portion)
30 Pneumatic cushion tire 32 Side groove

Claims (7)

In a pneumatic cushion tire having at least one tread rubber layer, and a base rubber layer in contact with the rim on the radially inner side of the tread rubber layer,
A pneumatic cushion tire characterized in that a side groove extending from a tire side portion toward a tire equatorial plane is disposed in the tread rubber layer.   The pneumatic cushion tire according to claim 1, wherein the side grooves are arranged on both sides of the tire equatorial plane.   The pneumatic cushion tire according to claim 1 or 2, wherein the side grooves are formed continuously or intermittently along the tire circumferential direction.   The pneumatic cushion tire according to any one of claims 1 to 3, wherein the side groove extends parallel to the tire axial direction. The height from the base line of the rim to the center in the tire side portion of the side groove is 0.35 to 0.8 times the tire cross-section height,
The width in the tire radial direction of the side groove is 0.03 to 0.35 times the tire cross-sectional height,
The pneumatic cushion tire according to any one of claims 1 to 4, wherein a depth of the side groove in the tire axial direction is 0.15 to 0.7 times a cross-sectional width on one side of the tire.   The pneumatic cushion tire according to any one of claims 1 to 4, wherein a shape of a tire equatorial plane side tip portion of the side groove is a flask shape.   In the side groove, the ratio of the widest width seen in the tire radial direction in the flask shape and the width seen in the tire radial direction at the tire side portion is in the range of 1.03 to 1.4. The pneumatic cushion tire according to claim 6, wherein the pneumatic tire is a pneumatic tire.

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