WO2011013357A1 - 建設車両用タイヤ - Google Patents
建設車両用タイヤ Download PDFInfo
- Publication number
- WO2011013357A1 WO2011013357A1 PCT/JP2010/004776 JP2010004776W WO2011013357A1 WO 2011013357 A1 WO2011013357 A1 WO 2011013357A1 JP 2010004776 W JP2010004776 W JP 2010004776W WO 2011013357 A1 WO2011013357 A1 WO 2011013357A1
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- WIPO (PCT)
- Prior art keywords
- tread
- tire
- narrow groove
- belt layer
- width
- Prior art date
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/0311—Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation
- B60C11/0316—Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation further characterised by the groove cross-section
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/0311—Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/0306—Patterns comprising block rows or discontinuous ribs
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
- B60C2011/0016—Physical properties or dimensions
- B60C2011/0033—Thickness of the tread
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C2011/0337—Tread patterns characterised by particular design features of the pattern
- B60C2011/0339—Grooves
- B60C2011/0341—Circumferential grooves
- B60C2011/0348—Narrow grooves, i.e. having a width of less than 4 mm
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C2011/0337—Tread patterns characterised by particular design features of the pattern
- B60C2011/0339—Grooves
- B60C2011/0381—Blind or isolated grooves
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C2200/00—Tyres specially adapted for particular applications
- B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles
- B60C2200/065—Tyres specially adapted for particular applications for heavy duty vehicles for construction vehicles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/28—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers characterised by the belt or breaker dimensions or curvature relative to carcass
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T152/00—Resilient tires and wheels
- Y10T152/10—Tires, resilient
- Y10T152/10495—Pneumatic tire or inner tube
- Y10T152/10765—Characterized by belt or breaker structure
- Y10T152/10801—Structure made up of two or more sets of plies wherein the reinforcing cords in one set lie in a different angular position relative to those in other sets
Definitions
- the present invention relates to a construction vehicle tire, and more particularly, to a construction vehicle tire in which heat generation and crack generation at the outermost belt end are suppressed.
- the outermost belt layer in construction vehicle tires traveling on rough terrain is generally set wide for the purpose of carcass protection, and setting a groove in the vicinity of the outermost belt layer starts from the belt end. There was a tendency to avoid the tread drop due to the tread cut.
- the object of the present invention is to solve these problems, and the purpose thereof is to improve heat dissipation near the outermost belt layer and to suppress the occurrence of cracks from the end of the outermost belt layer.
- the object is to provide tires for construction vehicles.
- the inventor has made extensive studies to solve the above problems, and as a result, the cracks generated from the outermost belt layer are extended in the circumferential direction by grounding the vicinity of the belt end when a load is applied to the tire during running. This is due to the combined radial-width cross-sectional shear strain, which is a combination of the strain that occurs when the belt shrinks in the width direction within the tread and the strain that occurs when the tread rubber is compressed and the tread is pushed in the width direction. In addition, it has been found that the heat generated by the tread during tire rolling promotes crack propagation.
- the inventor conducted extensive research on the behavior of the tire tread, and in particular for construction vehicle tires having belts with high circumferential rigidity, the center of the tread width direction is centered around the center position of the tread half width.
- tread rubber When tread rubber is deformed in the radial direction when internal pressure is applied, the tire tread tends to touch the inner side in the tread width direction in the range of 25% to 50% of the tread half width from the end of the tread. I found out. Therefore, the inventor placed the end portion of the outermost belt layer closer to the center than the position separated from the tread end portion by a distance of 25% of the tread half-width, thereby pushing out deformation of the tread that is usually on the outer side in the width direction.
- the present inventors have obtained new knowledge that it can be further relaxed and the above-mentioned shear strain in the cross section in the diameter-width direction can be further suppressed.
- a force acts in the direction of closing the narrow groove when the tire contacts the ground, and cracks occur at the groove bottom. They also found that progress can be suppressed.
- the gist configuration of the present invention for solving the above-described problems is as follows.
- a tire for a construction vehicle having a belt composed of a plurality of layers on a radially outer side of a crown portion of a carcass straddling a toroidal shape between a pair of bead portions The outermost belt layer on the outermost radial direction of the belt has a width of 50% or more of the tread width, When the tread thickness at the end of the outermost belt layer is T, the distance between the end of the outermost belt layer and the bottom of the narrow groove is in the range of 15 to 100% of the tread thickness T.
- a tire for a construction vehicle having a groove When the tread thickness at the end of the outermost belt layer is T, the distance between the end of the outermost belt layer and the bottom of the narrow groove is in the range of 15 to 100% of the tread thickness T.
- the end of the outermost belt layer is located closer to the center in the tread width direction than a position spaced a distance of 25% of the tread half-width from the end of the tread.
- the ratio GW / D of the width GW to the depth D is in the range of 5 to 25%, the above (1) to (5)
- the tread extrusion deformation is eased and the heat dissipation is improved to generate and propagate cracks from the outermost belt end. And tread separation due to cracks can be prevented.
- Narrow groove which is a plan view showing the tread portion of the tire in the case of providing in the tire circumferential direction. It is sectional drawing of a tire at the time of providing a narrow groove in a tire width direction. Narrow groove which is a plan view showing the tread portion of the tire in the case of providing in the tire width direction. It is sectional drawing of a tire at the time of providing a narrow groove in a tire peripheral direction and making the position of the edge part of an outermost belt layer appropriate. It is sectional drawing of a tire at the time of providing a narrow groove in a tire width direction and making the position of the edge part of an outermost belt layer appropriate.
- FIG. 6 is a plan view showing a tread portion of a tire in Invention Example 5.
- FIG. 6 is a cross-sectional view of a tire in Invention Example 4.
- FIG. It is sectional drawing of the conventional tire. It is a top view which shows the tread part of the conventional tire.
- a construction vehicle tire (hereinafter referred to as “tire”) according to the present invention has a carcass 1 straddling a toroidal shape between a pair of bead cores (not shown).
- a belt 2 composed of a plurality of layers, that is, six belt layers in the illustrated example, is arranged outside the crown portion of the carcass 1 in the radial direction.
- the belt layer located on the outermost side in the tire radial direction is referred to as the outermost belt layer 3.
- T be the length of a perpendicular line that extends from the end of the tire radial direction outermost belt layer to the tread surface.
- the outermost belt layer 3 is wider than the first and second belt layers from the inner side in the tire radial direction, and the second belt layer from the outer side in the tire radial direction is the widest.
- a narrow groove 4 extending in the tread circumferential direction is provided at a position corresponding to the outermost belt layer 3 of the tread.
- the distance L between the end of the outermost belt layer 3 and the bottom 5 of the narrow groove is set within a range of 15 to 100% of the tread thickness T of the end of the outermost belt layer.
- the distance L between the end portion of the outermost belt layer 3 and the bottom portion 5 of the narrow groove is the shortest distance between the end point of the outermost belt layer 3 and the bottom portion 5 of the narrow groove.
- the “point” of the “end point” is the center position of the thickness of the line, and the “bottom portion” is the bottom when the bottom surface of the narrow groove is flat.
- the bottom surface of the narrow groove has a curved surface
- the curved portion of the surface that protrudes inward of the diameter that forms the boundary between the narrow groove and the tread is referred to as a bottom portion.
- the “thin groove” means a groove whose depth is three times or more the opening width.
- the outermost belt layer 3 has a width of 50% or more of the tread width TW. In the illustrated example, the end of the outermost belt layer is in the tread width direction by a distance of 25% of the tread half width from the end of the tread.
- the inclination angle of the first and second belt layers from the inner side in the tire radial direction with respect to the tire circumferential direction is smaller than the inclination angle of the outermost belt layer 3 with respect to the tire circumferential direction.
- FIG. 2 is a plan view showing a tread portion of the tire according to the first embodiment of the present invention.
- the tread portion extends from the tread end toward the tire equator to the adjacent region of the tire equator, and has a plurality of tapered lateral grooves 6.
- the lug 7 is formed by dividing the tread surface by the lateral groove 6.
- a central circumferential groove 8 which is a narrow groove extending on the equator of the tire, and a lateral groove 6 on one end side of the tread and a lateral groove 6 on the other end side are extended in a direction crossing the equator of the tire.
- transverse grooves 9 that are alternately continuous.
- the depth of the transverse groove 9 is greater than that of the central circumferential groove 8, but it is the same depth or even if the central circumferential groove 8 is deeper than the central circumferential groove 8. good.
- the narrow groove 4 is also provided in the vicinity of the end portion 10 of the outermost belt layer in the tread portion.
- the specific positional relationship between the end 10 of the outermost belt layer and the narrow groove 4 is as described above.
- the narrow groove 4 has a distance L between the end of the outermost belt layer and the bottom 5 of the narrow groove 4 being the outermost. It is provided so as to be in the range of 15 to 100% of the tread thickness T at the end of the outer belt layer.
- the narrow grooves extending in the circumferential direction are linear, but they may extend zigzag.
- the narrow groove 4 is connected to the lateral groove 6, but the narrow groove 4 may not be connected to the lateral groove 6.
- the tread extrusion deformation is mitigated, the crack generation time from the end of the outermost belt layer can be delayed, and the heat dissipation in the region is enhanced, so that The progress of cracks generated from the end portion of the outer belt layer can be suppressed.
- the range in which the narrow groove 4 is provided is the above range because if it is less than 15%, cracks generated at the end of the belt are likely to be connected to the bottom 5 of the narrow groove. This is because the effect of the present invention is lowered because the effect of improving the heat dissipation is not expected although there is a slight effect in the suppression.
- the width of the outermost belt layer 3 is 50% or more of the tread width TW is that if it is less than 50%, the carcass is not sufficiently protected.
- at least one of the belt layers other than the outermost belt layer may have an inclination angle of 10 ° or less with respect to the tire circumferential direction. preferable.
- running wind the air flow during traveling of the vehicle is increased, which is particularly effective in that heat dissipation is enhanced.
- FIG. 3 is a cross-sectional view of a tire according to the second embodiment of the present invention.
- the second embodiment is different from the first embodiment in that the narrow grooves 4 are extended in the tire width direction.
- FIG. 4 is a plan view of the tire tread portion at this time.
- the narrow groove 4 extends along the tire width direction from the vicinity of the end 10 of the outermost belt layer toward the center of the tread.
- the narrow groove 4 has a distance L between the end of the outermost belt layer 3 and the bottom 5 of the narrow groove within a range of 15 to 100% of the tread thickness T at the end of the outermost belt layer. It is provided as.
- the configuration relating to the lateral groove 6, lug 7, central circumferential groove 8, and transverse groove 9 is the same as that of the first embodiment.
- the narrow groove 4 is connected to the transverse groove 9, but the narrow groove 4 may not be connected to the transverse groove 9.
- the narrow groove 4 when the narrow groove 4 is provided so as to extend in the tire width direction, it is possible to suppress a decrease in rigidity in the width direction in the vicinity of the narrow groove 4, and to suppress an increase in movement at the time of tire crossing. It is possible to prevent the wear performance from deteriorating. Further, when the crack is generated at the bottom of the narrow groove compared to the case where the narrow groove is provided in the circumferential direction, the stress applied to the portion is small, so that the block can be prevented from falling off. Further, since the tread surface area increases, an increase in heat dissipation can be expected, and the progress of cracks generated from the end portion of the outermost belt layer can be suppressed.
- the end of the outermost belt layer 3 is located at the center of the tread in the tread width direction from the point P separated from the end of the tread by a distance of 25% of the tread half width in the tread width direction. It is preferable to be close.
- the tire tread is subjected to deformation that contacts the inner side in the tread width direction. For this reason, the extrusion deformation of the tread due to the force applied to the outer side in the tread width direction is alleviated, and the end portion of the outermost belt layer is located in a region where the shear strain in the cross section in the radial-width direction is further suppressed.
- the amount of the tread rubber that is deformed is reduced as the outermost belt layer is deformed as compared with the case where the outermost belt layer is located at the position corresponding to the point P or closer to the tread end than the point P. It becomes.
- the crack generation time from the end of the outermost belt layer can be further delayed.
- the end of the outermost belt layer 3 is preferably located closer to the center in the tread width direction than the end of the fourth belt layer from the inner side in the tire radial direction. This is because the distortion of the end portion of the outermost belt layer generated by the movement of the fourth belt layer from the inner side in the tire radial direction can be suppressed.
- the outermost belt layer 3 is preferably wider than the first and second belt layers from the inner side in the tire radial direction. This is particularly to protect the first and second belt layers from the inside in the tire radial direction where the tension load is large. Further, it is preferable that the second belt layer from the outer side in the tire radial direction is the widest. This is to protect the first to fourth belt layers from the inside in the tire radial direction. Furthermore, the inclination angle of the first and second belt layers from the inner side in the tire radial direction with respect to the tire circumferential direction is preferably smaller than the inclination angle of the outermost belt layer 3 with respect to the tire circumferential direction. This is because it is possible to suppress the occurrence of cracks at the end of the outermost belt layer 3 while suppressing the diameter growth of the tire.
- the narrow groove 4 when the narrow groove 4 is extended in the tire circumferential direction, from the point P where the narrow groove 4 is separated in the tread width direction by a distance of 25% of the tread half width from the end portion of the tread. It is preferable to be near the center of the tread in the tread width direction. As a result, the narrow groove is located in a region where deformation occurs in which the tire tread comes into contact with the tread width inward in the tread width direction. Can be suppressed.
- the ratio GW / D A range of 5 to 25% is preferable. Because, if it is less than 5%, the running wind does not reach the bottom 5 of the groove and the heat dissipation effect is low. This is because the performance is degraded.
- the narrow groove 4 can be provided in the land portion of the lug 7 defined by the lateral groove 6.
- the increase in heat dissipation is slightly increased, but the decrease in the tread rigidity is suppressed, the wear resistance is decreased, and the block is dropped. Risk can be reduced.
- the narrow groove 4 When extending the narrow groove in the tire circumferential direction, or when providing the narrow groove in the land portion of the lug defined by the lateral groove, as shown in FIG. 9, the narrow groove 4 is formed on the outermost belt layer. With respect to a perpendicular line that extends from the end of 3 to the tread surface of the tire, it can be inclined from the bottom 5 of the narrow groove 4 toward the tread surface toward the outside of the vehicle when the tire is mounted on the vehicle.
- the tilt angle is preferably 0 to 30 °.
- a size 53 / 80R63 tire was assembled on a rim having a rim width of 36 inches.
- An indoor drum test and an abrasion resistance test were performed using a test tire having an internal pressure of 600 kPa.
- tires of the type shown in FIGS. 10 and 11 were prepared as conventional tires. Based on the structure having the six belt layers, as shown in Table 1, tires according to Invention Examples 1 to 5, 7, and 9 were produced by providing narrow grooves extending in the tire circumferential direction. Of these, tests were conducted by changing the ratio of the width and depth of the grooves and the presence or absence of connection to the lateral grooves.
- Tables 1 to 3 show the specifications of the tires of the conventional examples and Invention Examples 1 to 9.
- “on the outermost belt layer” means that the distance between the end of the outermost belt layer and the bottom of the outermost belt layer is 15 to 100% of the tread thickness T.
- “1/8 point” refers to a point (for example, point P in FIG. 1) that is separated from the end of the tread by a distance of 25% of the tread half width.
- the end portions of the first and second belt layers from the inner side in the tire radial direction are located at positions 53% and 55% apart from the tread end portions, respectively.
- the end of the fourth belt layer from the inner side in the tire radial direction is located 30% apart from the end of the tread at half the width of the tread, and the position of these ends is common to the invention examples 1 to 9 and the conventional example. ing.
- ⁇ 25% '' of ⁇ the position of the end of the outermost belt layer '', ⁇ 40% '' means that the end of the outermost belt layer is ⁇ 25% '' of the tread half width from the end of the tread, It means that it is in a position separated by a distance of “40%”.
- specifications not shown in the tables of Invention Examples 2 and 7 are common, and specifications not shown in the tables of Invention Examples 6 and 8 are common.
- Table 3 the specifications not shown in the tables of Invention Examples 1 and 9 are common.
- the indoor drum test conditions are a load of 82.5 t, a side force of 121 kN, a drum diameter of 5 m, and a traveling speed of 8 km / h.
- the abrasion resistance test conditions were as follows. The above tire was mounted on the front wheel of a 320-ton dump truck, and the actual road (unpaved road) was run at a speed of 15 km / h at a low load for about 5000 km. Abrasion loss was calculated by measuring the depth of the thin groove after abrasion. The test results are shown in Table 4 below.
- Invention Example 2 and Invention Example 5 differ only in whether the narrow groove is connected to the lateral groove or stays in the land portion of the lug, and other specifications are common.
- the abrasion resistance index of Invention Example 2 is 80%
- the crack occurrence length of the bottom of the narrow groove is 10 mm
- the abrasion resistance index of Invention Example 5 is 90%.
- the wear resistance and the block drop-off suppressing effect are better.
- the outermost belt end temperature is 88 ° C. in Invention Example 5, whereas it is 82 ° C. in Invention Example 2, and the heat dissipation is better when the narrow groove is connected to the lateral groove. The result is good. Furthermore, Invention Example 5 and Invention Example 6 are different only in whether the narrow groove is provided extending in the circumferential direction or extending in the width direction, and other specifications are common.
- the abrasion resistance index of Invention Example 5 is 90% and the crack occurrence length of the bottom of the narrow groove is 5 mm
- the abrasion resistance index of Invention Example 6 is 95% and the bottom of the narrow groove is The length of occurrence of cracks is 0 mm, and the invention example 6 in which the narrow grooves are provided in the width direction has better wear resistance and the effect of preventing the block from falling off.
- Inventive Examples 7 and 8 in which the end position of the outermost belt layer is optimized by comparing the Inventive Examples 2 and 7 and the Inventive Examples 6 and 8, are the outermost belt ends of Inventive Examples 2 and 3, respectively. It can be seen that the crack length at is small. Further, comparison between Invention Examples 1 and 9 reveals that Invention Example 1 in which the position in the width direction of the narrow groove is optimized is shorter than Invention Example 9 in that the length of cracks generated at the bottom of the narrow groove is smaller.
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Abstract
Description
そこで、発明者は、上記最外側ベルト層の端部をトレッド端部からトレッド半幅の25%の距離離間した位置より中央寄りに位置させることにより、通常幅方向外側にかかる上記トレッドの押し出し変形をさらに緩和させ、上記の径-幅方向断面内せん断歪をさらに抑制することができることの新規知見を得た。
また、上記の細溝をトレッド端部からトレッド半幅の25%の距離離間した位置より中央寄りに位置させることにより、タイヤ接地時に細溝が閉じる方向に力が働き、溝底でのクラックの発生及び進展を抑制できることも併せて見出した。
(1)一対のビード部間にトロイダル状に跨るカーカスのクラウン部の径方向外側に複数層からなるベルトを有する建設車両用タイヤにおいて、
前記ベルトの最も径方向外側の最外側ベルト層は、トレッド幅の50%以上の幅を有し、
前記最外側ベルト層の端部におけるトレッド厚さをTとしたとき、前記最外側ベルト層の端部と細溝の底部との距離が前記トレッド厚さTの15~100%の範囲にある細溝を有する、建設車両用タイヤ。
カーカス1のクラウン部の径方向外側に複数層、図示例では6層のベルト層からなるベルト2が配置されている。これら複数のベルト層のうち、最もタイヤ径方向外側にあるベルト層を最外側ベルト層3と称する。ここで、タイヤ径方向最外側ベルト層の端部からトレッド踏面に下ろした垂線の長さをTとしておく。
Tとしておく。図示例では、最外側ベルト層3は、タイヤ径方向内側から1、2層目のベルト層より幅広であり、タイヤ径方向外側から2番目のベルト層が最も幅広である。
さらに、トレッドの最外側ベルト層3に対応する位置にはトレッド周方向に延びる細溝4が設けられている。具体的には、最外側ベルト層3の端部と細溝の底部5との距離Lを、最外側ベルト層の端部のトレッド厚さTの15~100%の範囲内として設けている。
ここでいう最外側ベルト層3の端部と細溝の底部5との距離Lとは、最外側ベルト層3の端点と、細溝の底部5との最短距離である。「端点」の「点」とは、線の厚み中心位置であり、「底部」とは、細溝の底面が平坦である場合は、その底面が底部となる。一方、細溝の底面が曲面をなしている場合には、細溝とトレッドの境界をなす径内側に凸な面のうち、湾曲している部分を底部という。また、「細溝」とは、深さが開口幅に対して3倍以上の大きさの溝をいう。
なお、最外側ベルト層3はトレッド幅TWの50%以上の幅を有し、図示例では、最外側ベルト層の端部は、トレッドの端部からトレッド半幅の25%の距離だけトレッド幅方向に離間した点Pに対応する位置にある。「点Pに対応する位置にある」とはタイヤ幅方向断面において、点Pを通りタイヤ径方向に平行な直線上にあることをいう。
また、図示例では、タイヤ径方向内側から1、2層目のベルト層のタイヤ周方向に対する傾斜角度は、最外側ベルト層3のタイヤ周方向に対する傾斜角度より小さい。
また、トレッド中央部には、タイヤの赤道上を延びる幅狭の溝である、中央周溝8及び、タイヤの赤道を横切る向きに延び、トレッドの一端側の横溝6と他端側の横溝6とに交互に連続する横断溝9を有している。
なお、図2においては中央周溝8より横断溝9の方の深さが大きく表されているが、同じ深さとするか、あるいは、中央周溝8の方が溝の深さが深くても良い。
なお、最外側ベルト層3の幅をトレッド幅TWの50%以上としているのは、50%未満では、カーカスの保護が不十分となってしまうからである。
また、建設車両用タイヤでは、特に高いタイヤの周方向剛性が必要となるため、最外側ベルト層以外のベルト層のうち少なくとも1層以上がタイヤ周方向に対する傾斜角度が10°以下であることが好ましい。
横溝6、ラグ7、中央周溝8、横断溝9に関する構成は第一の実施形態と同様である。
なお、図4では細溝4が横断溝9と繋がっているが、細溝4は横断溝9と繋がっていなくてもよい。
これにより、最外側ベルト端の位置では、タイヤ踏面がトレッド幅方向内側に接地する変形を受けることとなる。このため、トレッド幅方向外側にかかる力によるトレッドの押し出し変形が緩和され、径-幅方向断面内せん断歪がさらに抑制される領域に最外側ベルト層の端部が位置することとなる。
また、最外側ベルト層が点Pに対応する位置又は点Pより上記トレッド端部側に位置する場合に比べて、最外側ベルト層の変形に伴って、変形するトレッドゴムの量が減少することとなる。
これらの効果により、最外側ベルト層の端部からの亀裂発生時期をさらに遅らせることができる。
なお、図5、6に示すように、最外側ベルト層3の端部は、タイヤ径方向内側から4層目のベルト層の端部よりトレッド幅方向中央寄りに位置することが好ましい。
これにより、タイヤ径方向内側から4層目のベルト層の動きによって発生する最外側ベルト層の端部の歪みを抑制することができるからである。
また、最外側ベルト層3は、タイヤ径方向内側から1、2層目のベルト層より幅広であることが好ましい。
特に張力負担の大きいタイヤ径方向内側から1、2層目のベルト層を保護するためである。
さらに、タイヤ径方向外側から2番目のベルト層が最も幅広であることが好ましい。
タイヤ径方向内側から1~4層目のベルト層を保護するためである。
さらにまた、タイヤ径方向内側から1、2層目のベルト層のタイヤ周方向に対する傾斜角度を、最外側ベルト層3のタイヤ周方向に対する傾斜角度より小さくすることが好ましい。
なぜなら、これにより、タイヤの径成長を抑制しつつ、最外側ベルト層3の端部での亀裂の発生を抑制することができるからである。
これにより、上記のタイヤ踏面がトレッド幅方向内側に接地する変形が生じる領域に細溝が位置するため、タイヤ接地時に細溝が閉じる方向に力が働き、溝底でのクラックの発生及び進展を抑制できる。
供試タイヤは、まず、従来タイヤとして図10、図11に示すタイプのタイヤを用意した。この6層のベルト層を有する構造を基本として、表1に示すように、細溝をタイヤ周方向に延在させて設けたものを発明例1~5、7、9にかかるタイヤとして試作し、これらの中で、溝の幅と深さの比や横溝への接続の有無を変えて試験を行った。また、細溝をタイヤ幅方向に延在させて設けたものを発明例6、8にかかるタイヤとして試作した。
従来例、及び発明例1~9のタイヤの緒元は表1~3に示している。
なお、表1、3において、「最外側ベルト層上」とは、細溝が最外側ベルト層の端部と当該細溝の底部との距離がトレッド厚さTの15~100%の範囲にあることをいう。
「1/8点」とは、トレッドの端部からトレッド半幅の25%の距離離間した点(例えば図1では点P)をいう。
また、発明例1~9及び従来例について、タイヤ径方向内側から1、2層目のベルト層の端部は、トレッドの端部からそれぞれトレッド半幅の53%、55%離間した位置にあり、タイヤ径方向内側から4層目のベルト層の端部は、トレッドの端部からトレッド半幅の30%離間した位置にあり、これらの端部の位置は発明例1~9及び従来例について共通している。
表2における、「最外側ベルト層の端部の位置」の「25%」、「40%」とは、最外側ベルト層の端部がトレッドの端部からそれぞれトレッド半幅の「25%」、「40%」の距離だけ離間した位置にあることをいう。
また、表2においては、発明例2と7の表中に示さない諸元は共通しており、発明例6と8の表中に示さない諸元は共通している。同様に、表3においては、発明例1と9の表中に示さない諸元は共通している。
また、発明例1~9にかかるタイヤは全て、従来例にかかるタイヤよりも最外側ベルト層の端部における亀裂の長さ(従来例を100%としている)が小さい。このことから、本発明例にかかるタイヤは、亀裂の発生を遅延させる効果が従来例のタイヤよりも高いことがわかる。
また、発明例2と発明例4は、細溝を設ける角度のみが異なっており、他のスペックは共通している。これらのタイヤの試験結果を比較すると、細溝底のクラック発生長さが発明例2では10mmであるのに対し、発明例4では5mmとなっており、細溝を傾けて設けた発明例4の方が、ブロックの脱落の抑制効果が高いという結果が出ている。
さらに、発明例2と発明例5は、細溝が横溝と接続されているか、ラグの陸部に留まるかのみが異なっており、他のスペックは共通している。これらのタイヤの試験結果を比較すると、発明例2の耐磨耗指数が80%、細溝底のクラック発生長さが10mmであるのに対して、発明例5の耐磨耗指数が90%、細溝底のクラック発生長さが5mmであり、細溝がラグの陸部に留まる発明例5の方が、耐摩耗性及びブロックの脱落抑制効果が良好となっている。一方で放熱性に関しては、最外層ベルト端温度が、発明例5は88℃であるのに対して発明例2では82℃であり、細溝が横溝と接続されている方が、放熱性が良好という結果となっている。
さらにまた、発明例5と発明例6は細溝を周方向に延在させて設けているか幅方向に延在させて設けているかのみが異なっており他のスペックは共通しており、これらの試験結果を比較すると、発明例5の耐磨耗指数が90%、細溝底のクラック発生長さが5mmであるのに対して、発明例6の耐磨耗指数が95%、細溝底のクラック発生長さが0mmであり、細溝を幅方向に設ける発明例6の方が、耐摩耗性及びブロックの脱落抑制効果が良好となっている。
また、発明例1と9との比較により、細溝の幅方向位置を好適化した発明例1は発明例9より、細溝底に発生したクラックの長さが小さいことがわかる。
2 ベルト
3 最外側ベルト層
4 細溝
5 細溝の底部
6 横溝
7 ラグ
8 中央周溝
9 横断溝
10 最外側ベルト層の端部
Claims (8)
- 一対のビード部間にトロイダル状に跨るカーカスのクラウン部の径方向外側に複数層からなるベルトを有する建設車両用タイヤにおいて、
前記ベルトの最も径方向外側の最外側ベルト層は、トレッド幅の50%以上の幅を有し、
前記最外側ベルト層の端部におけるトレッド厚さをTとしたとき、前記最外側ベルト層の端部と細溝の底部との距離が前記トレッド厚さTの15~100%の範囲にある細溝を有する、建設車両用タイヤ。 - 前記最外側ベルト層の端部は、前記トレッドの端部からトレッド半幅の25%の距離離間した位置よりトレッド幅方向中央寄りにあることを特徴とする、請求項1に記載の建設車両用タイヤ。
- 前記細溝は、トレッド周方向に延びる、請求項1に記載の建設車両用タイヤ。
- 前記細溝は、トレッド幅方向に延びる、請求項1に記載の建設車両用タイヤ。
- 前記細溝は、前記トレッドの端部からトレッド半幅の25%の距離離間した位置よりトレッド幅方向中央寄りにあることを特徴とする、請求項3に記載の建設車両用タイヤ。
- 前記細溝の開口幅をGW、深さをDとしたとき、幅GWと深さDの比GW/Dが5~25%の範囲にある、請求項1~5のいずれか一項に記載の建設車両用タイヤ。
- 前記細溝は、前記横溝によって区画される陸部内に留まる、請求項3に記載の建設車両用タイヤ。
- 前記細溝は、該細溝の底部からトレッド表面に向かって、タイヤの車両装着時の車両外側に傾斜している、請求項3又は7に記載の建設車両用タイヤ。
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BR112012001846A BR112012001846A2 (pt) | 2009-07-27 | 2010-07-27 | pneu para veículo de construção. |
EP10804108.8A EP2460671B1 (en) | 2009-07-27 | 2010-07-27 | Tire for construction machine |
CN201080040024.XA CN102481810B (zh) | 2009-07-27 | 2010-07-27 | 工程车辆用轮胎 |
ES10804108.8T ES2522991T3 (es) | 2009-07-27 | 2010-07-27 | Neumático para máquina de construcción |
US13/387,189 US8955568B2 (en) | 2009-07-27 | 2010-07-27 | Tire for construction vehicle |
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JP2010-167891 | 2010-07-27 |
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EP (2) | EP2896513B1 (ja) |
JP (1) | JP5623813B2 (ja) |
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JP2017222190A (ja) * | 2016-06-13 | 2017-12-21 | 株式会社ブリヂストン | 空気入りタイヤ |
WO2023112353A1 (ja) * | 2021-12-14 | 2023-06-22 | 株式会社ブリヂストン | タイヤ |
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JP5731242B2 (ja) * | 2011-03-14 | 2015-06-10 | 株式会社ブリヂストン | 農業用タイヤ |
JP5804833B2 (ja) * | 2011-07-29 | 2015-11-04 | 株式会社ブリヂストン | 空気入りタイヤ |
JP6047362B2 (ja) * | 2012-10-03 | 2016-12-21 | 株式会社ブリヂストン | ラグ付きタイヤ及びその製造方法 |
JP6058341B2 (ja) * | 2012-10-05 | 2017-01-11 | 株式会社ブリヂストン | 重荷重用空気入りタイヤ |
JP5695099B2 (ja) * | 2013-01-30 | 2015-04-01 | 株式会社ブリヂストン | 建設車両用空気入りタイヤ |
JP5799043B2 (ja) * | 2013-03-13 | 2015-10-21 | 株式会社ブリヂストン | 空気入りタイヤ |
JP5868353B2 (ja) * | 2013-07-05 | 2016-02-24 | 株式会社ブリヂストン | 重荷重用空気入りタイヤ |
JP6243233B2 (ja) * | 2014-01-17 | 2017-12-06 | 株式会社ブリヂストン | タイヤ |
JP6258737B2 (ja) * | 2014-03-20 | 2018-01-10 | 株式会社ブリヂストン | タイヤ |
JP2018008664A (ja) * | 2016-07-15 | 2018-01-18 | 横浜ゴム株式会社 | 空気入りタイヤ |
FR3058928A1 (fr) * | 2016-11-22 | 2018-05-25 | Compagnie Generale Des Etablissements Michelin | Bande de roulement de pneu pour engin de genie civil comportant des creux de ventilation ameliores |
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EP2460671B1 (en) | 2014-08-20 |
US8955568B2 (en) | 2015-02-17 |
ES2522991T3 (es) | 2014-11-20 |
CN102481810A (zh) | 2012-05-30 |
EP2460671A1 (en) | 2012-06-06 |
CN102481810B (zh) | 2015-04-08 |
JP2011046372A (ja) | 2011-03-10 |
JP5623813B2 (ja) | 2014-11-12 |
BR112012001846A2 (pt) | 2017-05-16 |
EP2460671A4 (en) | 2013-04-17 |
EP2896513B1 (en) | 2017-03-29 |
US20120118461A1 (en) | 2012-05-17 |
EP2896513A1 (en) | 2015-07-22 |
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