JP2007168520A - Tire with lugs - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire 2 with lugs suppressed with burying in mud without increasing production cost. <P>SOLUTION: This tire 2 is provided with a tread 4 provided with a main body 16 and many lugs 18 projecting radially substantially outward from the main body 16, a pair of side walls 6 extending radially substantially inward from an end of the tread 4, a pair of beads 8 extending further radially substantially inward from the side wall 6, and a projection 14 projecting to the axially outside from the side faces. The lugs 18 are alternately arranged on left and right sides in a rotating direction. A distal end 32 of the projection 14 is located at the radially inside of roots 36 of the lugs 18. A ratio of a projecting length of the projection 14 from the axially maximum width of the lug 18 to the axially maximum width of the lug 18 is ≥0.05 and ≤0.15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tire with a lug that can be attached to an agricultural machine and a light civil engineering construction machine that travel in wetlands, soft ground, and the like.

  Agricultural machines and light civil engineering construction machines are equipped with lug-equipped tires that allow for workability in wetlands and soft ground.

  In tires with lugs, the tread has a number of lugs. The lug extends from the vicinity of the equator plane toward the end of the tread on the rear side in the rotational direction. The lugs are alternately arranged on the left and right in the rotation direction. This lug protrudes substantially outward in the radial direction from the main body of the tread. Propulsion is generated by the mud scratching mud in wetlands and soft ground. The traction force of this tire is ensured by this lug.

Japanese Unexamined Patent Publication No. 6-320915 discloses an agricultural tire in which the continuous contact property of a lug is enhanced and clogging of mud at the center in the width direction (near the equator plane) is suppressed. This tire is configured so that the contact area of the end of the lug at the center is small.
JP-A-6-320915

  In wetlands and soft ground where the mud contains a lot of water, the rugged tires are buried in the mud. If the degree of burial is severe, the aircraft equipped with this tire will get stuck in mud and will not move. In order to suppress the burial of the tire in mud, there is a tire in which the width and surface shape of the tire are changed. If the width and surface shape of the tire are changed, the tire mass will increase. When the width and surface shape of the tire are changed, the running performance such as traction force, mud brushing property and riding comfort is changed. It is necessary to modify the mold used for the production of the tire, change the molding equipment, and the like. With this tire, the production cost increases.

  An object of the present invention is to provide a tire with a lug that is suppressed from being buried in mud without increasing the production cost.

  The tire with a lug according to the present invention includes a tread including a main body, and a large number of lugs protruding substantially outward in the radial direction from the main body, and a protrusion protruding outward in the axial direction from the side surface. The lugs are alternately arranged on the left and right in the rotation direction. The tip of this protrusion is located radially inward from the base of this lug. The ratio of the protrusion length of the protrusion from the maximum axial width of the lug to the maximum axial width of the lug is 0.05 to 0.15.

  Preferably, in this tire, an outer surface located radially outward of the protrusion is flat in a cross section along the radial direction. The angle formed by the outer surface with respect to the equator plane is 90 ° or more and 150 ° or less. Preferably, in this tire, the ratio of the length in the radial direction from the top surface of the lug to the tip of the protrusion with respect to the cross-sectional height is 0.60 or less. Preferably, in the tire, the tip of the protrusion is continuous in the rotation direction. Preferably, in the tire, the protrusions are arranged in the rotation direction at intervals.

  Since this lug-equipped tire is provided with a protrusion extending axially outward from the side surface, the area where the tire comes into contact with mud in wetlands and soft ground is increased as compared with a conventional tire having no protrusion. The buoyancy of the tire increases. In this tire, burial in mud is suppressed. Since the ratio of the protrusion length of the projection from the maximum axial width of the lug to the maximum axial width of the lug is 0.05 or more and 0.15 or less, the burial in the mud can be effectively suppressed. With this tire, the aircraft will not get stuck in the mud and become stuck. In order to suppress the burial of the tire, the width and shape of the tire need not be changed. In this tire, the running performance of the conventional tire can be maintained. Since it is not necessary to significantly remodel the mold and molding equipment used for the production of the tire, an increase in production cost can be suppressed.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 is a side view showing a lug-equipped tire 2 according to an embodiment of the present invention. FIG. 2 is a development view showing a part of the tire 2 of FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. In FIG. 1, an arrow line A represents the rotation direction of the tire 2. The direction perpendicular to the paper surface is the axial direction of the tire 2. In FIG. 2, the left-right direction is the axial direction of the tire 2. What is indicated by an arrow line A is the rotation direction of the tire 2. In FIG. 3, the vertical direction is the radial direction of the tire 2, and the horizontal direction is the axial direction of the tire 2. The tire 2 has a substantially bilaterally symmetric shape around a one-dot chain line CL in FIGS. 2 and 3. This alternate long and short dash line CL represents the equator plane of the tire 2.

  The tire 2 is attached to an agricultural machine. Examples of the agricultural machine include a tractor, a binder, a harvester, a combine, a rice transplanter, a transporter, and a tiller. The tire 2 may be attached to a light civil engineering construction machine such as a trencher and a dozer.

  The tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a belt 12, and a protrusion 14. Although not shown, the tire 2 includes a tube. This tube is filled with air.

  The tread 4 is made of a crosslinked rubber and has a shape protruding outward in the radial direction. The tread 4 includes a main body 16 and a large number of lugs 18 projecting outward from the main body 16 in the radial direction.

  The lug 18 extends from the vicinity of the equator plane toward the end of the tread 4. The lugs 18 are alternately arranged on the left and right in the rotation direction. The lug 18 scratches the mud to generate a driving force. The lug 18 ensures the traction force of the tire 2.

  The sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. The sidewall 6 is made of a crosslinked rubber. The sidewall 6 absorbs an impact from the road surface by bending. Further, the sidewall 6 prevents the carcass 10 from being damaged.

  The bead 8 extends from the sidewall 6 substantially inward in the radial direction. The bead 8 includes a core 20 and an apex 22 that extends radially outward from the core 20. The core 20 has a ring shape and includes a plurality of non-stretchable wires (typically steel wires). The apex 22 has a tapered shape that tapers outward in the radial direction, and is made of a highly hard crosslinked rubber.

  The carcass 10 includes a first carcass ply 24 and a second carcass ply 26. The first carcass ply 24 and the second carcass ply 26 are bridged between the beads 8 on both sides, and are along the inside of the tread 4 and the sidewall 6. The first carcass ply 24 and the second carcass ply 26 are wound around the core 20 from the inner side to the outer side in the axial direction. One carcass ply may be used for the carcass 10. Three or more carcass plies may be used.

  Although not shown, the first carcass ply 24 is composed of a first cord and a topping rubber. The absolute value of the angle formed by the first cord with respect to the equator plane is usually 10 ° or more and 50 ° or less. The second carcass ply 26 includes a second cord and a topping rubber. The absolute value of the angle formed by the second cord with respect to the equator plane is usually 10 ° or more and 50 ° or less. In the tire 2, the angle formed by the first cord with respect to the equator plane is opposite to the angle formed by the second cord with respect to the equator plane. The first cord and the second cord are usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The belt 12 includes a belt ply 28. The belt ply 28 is located on the inner side in the radial direction of the tread 4. The belt ply 28 is laminated outside the carcass 10 in the radial direction. The belt ply 28 reinforces the carcass 10. Two or more belt plies 28 may be used for the belt 12.

  Although not shown, the belt ply 28 is composed of a belt cord and a topping rubber. The absolute value of the angle formed by the belt cord with respect to the equator plane is usually 15 ° or more and 50 ° or less. Examples of a preferable material for the belt cord include steel and organic fibers. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The protrusion 14 protrudes outward in the axial direction from the side surface 30 of the tire 2. In the tire 2, the protrusion 14 is located between the lug 18 and the sidewall 6. In the tire 2, the tip 32 of the protrusion 14 is continuous in the rotation direction. The protrusion 14 has a bowl shape. In the projection 14, the outer surface 34 located on the radially outer side is flat in a cross section along the radial direction of the tire 2. The shape of the protrusion 14 is determined as appropriate in consideration of the running property of the tire 2 in wetlands and soft ground, the condition of the tire 2 being buried in mud, and the like.

  The protrusion 14 is made of a crosslinked rubber. In the tire 2, the material of the protrusion 14 is the same as that of the tread 4. The protrusion 14 may be made of a material different from that of the tread 4.

  Since the tire 2 includes the protrusions 14, the contact area with the mud increases as compared with the conventional tire. The buoyancy of the tire 2 is greater than that of a conventional tire without the protrusion 14. In the tire 2, burial in mud is suppressed. The aircraft equipped with the tire 2 does not get stuck in the mud and cannot move.

  In the tire 2, the tip 32 of the protrusion 14 is located radially inward of the base 36 of the lug 18. The lug 18 is buried in mud. In the tire 2, the traction force by the lug 18 is not impaired.

  In the tire 2, it is not necessary to change the configuration such as the width and shape of the tire 2 in order to suppress burial in the mud. In the tire 2, the performance of the conventional tire can be maintained. Since it is not necessary to significantly modify the mold and molding equipment used for the production of the tire 2, an increase in production cost can be suppressed.

  In FIG. 3, the left and right points PA are the outer ends of the lugs 18 positioned on the outer side in the axial direction which is the maximum axial width of the lugs 18. A double arrow line WB represents the axial length between the left and right outer ends. This length WB is the maximum axial width of the lug 18. A double arrow line WA represents the axial length from the tip 32 of the lug 18 to the outer end PA. The length WA is a protruding length of the protrusion 14 from the axial maximum width WB. Point PB is the intersection of the top surface 38 of the lug 18 and the equator plane. A solid line BBL is a bead base line passing through the heel 40 of the bead 8. A double arrow line LB represents a radial height from the bead base line to the point PB. The height LB is the cross-sectional height of the tire 2. A double arrow line LA represents a radial direction length from the tip 32 to the point PB. A solid line SL is a straight line passing through the outer surface 34 of the protrusion 14. The angle α represents an angle formed by the straight line SL with respect to the equator plane. This angle α is an angle formed by the outer surface 34 with respect to the equator plane.

  In the tire 2, the ratio (WA / WB) of the protrusion length WA of the protrusion 14 to the maximum axial width WB of the tire 2 is 0.05 or more and 0.15 or less. By setting the ratio (WA / WB) to 0.05 or more, the buoyancy of the tire 2 is increased. In the tire 2, burial in mud is suppressed. In this respect, the ratio (WA / WB) is more preferably equal to or greater than 0.06 and particularly preferably equal to or greater than 0.07. By setting this ratio (WA / WB) to be equal to or less than 0.15, adhesion of mud to the protrusions 14 is suppressed. In this respect, the ratio (WA / WB) is more preferably equal to or less than 0.14, and particularly preferably equal to or less than 0.13.

  In the tire 2, the ratio (LA / LB) of the radial length LA to the cross-sectional height LB of the tire 2 is 0.60 or less. When this ratio is set to 0.60 or less, the traction force by the lugs 18 is not impaired, and the protrusions 14 effectively suppress the tire 2 from being buried in the mud. In this respect, the ratio is more preferably equal to or less than 0.58, and particularly preferably equal to or less than 0.55. As described above, since the protrusion 14 is formed radially inward of the base 36 of the lug 18, the lower limit value of this ratio varies depending on the position of the base 36 of the lug 18. In the tire 2, the lower limit value of this ratio is 0.47.

  In the tire 2, the angle α is not less than 90 ° and not more than 150 °. By setting the angle α to 90 ° or more, mud adherence to the protrusions 14 is suppressed. In this respect, the angle α is more preferably 95 ° or more, and particularly preferably 100 ° or more. By setting this angle to 150 ° or less, the buoyancy of the tire 2 is effectively enhanced. In the tire 2, burial in mud is suppressed. From this viewpoint, the angle α is more preferably 140 ° or less, and particularly preferably 130 ° or less.

  FIG. 4 is a side view showing a lug tire 42 according to another embodiment of the present invention. FIG. 5 is a development view showing a part of the tire 42 of FIG. 4. 6 is a cross-sectional view taken along line VI-VI in FIG. In FIG. 4, an arrow line A represents the rotation direction of the tire 42. The direction perpendicular to the paper surface is the axial direction of the tire 42. In FIG. 5, the left-right direction is the axial direction of the tire 42. What is indicated by an arrow line A is the rotation direction of the tire 42. In FIG. 6, the vertical direction is the radial direction of the tire 42, and the horizontal direction is the axial direction of the tire 42. The tire 42 has a substantially bilaterally symmetric shape around the one-dot chain line CL in FIGS. 5 and 6. The alternate long and short dash line CL represents the equator plane of the tire 42.

  The tire 42 includes a tread 44, a sidewall 46, a bead 48, a carcass 50, a belt 52, and a protrusion 54. The tread 44 includes a large number of lugs 56 that protrude substantially outward in the radial direction. The tire 42 has the same configuration as the tire 2 of FIG.

  The protrusion 54 protrudes outward in the axial direction from the side surface 58 of the tire 42. In the tire 42, the protrusion 54 is located between the lug 56 and the sidewall 46. The protrusion 54 has a bowl shape. In the projection 54, the outer surface 60 located on the outer side in the radial direction is flat in a cross section along the radial direction of the tire 42. The protrusion 54 is made of a crosslinked rubber. In the tire 42, the material of the protrusion 54 is the same as that of the tread 44.

  The protrusion 54 is located on the radially inner side of the side surface portion 62 located on the outer side in the axial direction of the lug 56. The protrusions 54 are not disposed between the side surfaces 62 arranged in the rotation direction. In the tire 42, the protrusions 54 are arranged in the rotation direction at intervals. Since the tip 64 of the protrusion 54 is not continuous in the rotational direction, the mass of the tire 42 is reduced compared to the tire 2 of FIG.

  Since the tire 42 includes the protrusion 54, the contact area with the mud is increased as compared with the conventional tire. The buoyancy of the tire 42 is greater than that of a conventional tire without the protrusion 54. In the tire 42, burial in mud is suppressed. The aircraft with the tires 42 will not get stuck in the mud and cannot move.

  In the tire 42, the tip 64 of the protrusion 54 is located on the radially inner side with respect to the root 66 of the lug 56. The lug 56 is buried in mud. In the tire 42, the traction force by the lug 56 is not impaired.

  In the tire 42, it is not necessary to change the configuration such as the width and shape of the tire 42 in order to suppress the burial in the mud. In the tire 42, the performance of the conventional tire can be maintained. Since it is not necessary to significantly modify the mold and molding equipment used for the production of the tire 42, an increase in production cost can be suppressed.

  In FIG. 6, the left and right points PA are the outer ends of the lugs 56 positioned on the outer side in the axial direction that is the maximum axial width of the lugs 56. A double arrow line WB represents the axial length between the left and right outer ends. This length WB is the maximum axial width of the lug 56. A double arrow line WA represents the axial length from the tip 64 of the lug 56 to the outer end PA. This length WA is a protruding length of the protrusion 54 from the axial maximum width WB. Point PB is the intersection of the top surface 68 of the lug 56 and the equator plane. A solid line BBL is a bead base line. A double arrow line LB represents a radial height from the bead base line to the point PB. This height LB is the cross-sectional height of the tire 42. A double arrow line LA represents the length in the radial direction from the tip 64 of the lug 56 to the point PB. A solid line SL is a straight line passing through the outer surface 60 of the protrusion 54. The angle α represents an angle formed by the straight line SL with respect to the equator plane. This angle α is an angle formed by the outer surface 60 with respect to the equator plane.

  In the tire 42, the ratio (WA / WB) of the protrusion length WA of the protrusion 54 to the maximum axial width WB of the tire 42 is 0.05 or more and 0.15 or less. By setting the ratio (WA / WB) to be equal to or greater than 0.05, the buoyancy of the tire 42 is increased. In the tire 42, burial in mud is suppressed. In this respect, the ratio (WA / WB) is more preferably equal to or greater than 0.06 and particularly preferably equal to or greater than 0.07. By setting this ratio (WA / WB) to be equal to or less than 0.15, adhesion of mud to the protrusions 54 is suppressed. In this respect, the ratio (WA / WB) is more preferably equal to or less than 0.14, and particularly preferably equal to or less than 0.13.

  In the tire 42, the ratio (LA / LB) of the radial length LA to the sectional height LB of the tire 42 is 0.60 or less. When this ratio is set to 0.60 or less, the traction force by the lug 56 is not impaired, and the protrusion 54 effectively suppresses the burying of the tire 42 in the mud. In this respect, the ratio is more preferably equal to or less than 0.58, and particularly preferably equal to or less than 0.55. As described above, since the protrusion 54 is formed radially inward of the base 66 of the lug 56, the lower limit value of this ratio varies depending on the position of the base 66 of the lug 56. In the tire 42, the lower limit value of this ratio is 0.47.

  In the tire 42, the angle α is not less than 90 ° and not more than 150 °. By setting the angle α to 90 ° or more, adhesion of mud to the protrusion 54 is suppressed. In this respect, the angle α is more preferably 95 ° or more, and particularly preferably 100 ° or more. By setting this angle to 150 ° or less, the buoyancy of the tire 42 is effectively enhanced. In the tire 42, burial in mud is suppressed. From this viewpoint, the angle α is more preferably 140 ° or less, and particularly preferably 130 ° or less.

  The dimensions and angles of the tires 2 and 42 are measured in a state where the tires 2 and 42 are incorporated in a normal rim and the tires 2 and 42 are filled with air so as to have a normal internal pressure. During the measurement, no load is applied to the tires 2 and 42. In the present specification, the normal rim means a rim defined in a standard on which the tires 2 and 42 depend. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In this specification, the normal internal pressure means an internal pressure determined in the standard on which the tires 2 and 42 depend. “Maximum air pressure” in the JATMA standard, “maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, and “INFLATION PRESSURE” in the ETRTO standard are normal internal pressures.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
A tire with a lug of Example 1 having the basic configuration shown in FIGS. 1 and 4 and having the specifications shown in Table 1 below was obtained. The tire size is 13.6-24 4PR. For the carcass, a first carcass ply and a second carcass ply were used. The material of the first cord used in the first carcass ply is nylon fiber. The angle formed by the first cord with respect to the equator plane is 40 °. The material of the second cord used for the second carcass ply is nylon fiber. The angle formed by the second cord with respect to the equator plane is 40 °. The angle formed by the first cord with respect to the equator plane is opposite to the angle formed by the second cord with respect to the equator plane. A belt ply was used for the belt. The material of the belt cord used for this belt ply is nylon fiber. The angle formed by the belt cord with respect to the equator plane is 35 °. The ratio (WA / WB) of the protrusion length WA of the protrusion to the maximum axial width WB of the tire is 0.10. The angle α formed by the outer surface of the protrusion with respect to the equator plane is 110 °. The ratio (LA / LB) of the radial length LA from the intersection of the top surface of the lug and the equator plane to the tip of the protrusion with respect to the cross-sectional height LB of the tire is 0.50.

[Comparative Examples 2 and 3 and Examples 3 and 4]
A lug-equipped tire was obtained in the same manner as in Example 1 except that the ratio (WA / WB) was as shown in Table 1 below.

[Examples 2 and 5]
A lug-equipped tire was obtained in the same manner as in Example 1 except that the angle α was as shown in Table 1 below.

[Example 6]
A lug-equipped tire was obtained in the same manner as in Example 1 except that the ratio (LA / LB) was as shown in Table 1 below.

[Example 7]
A lug-equipped tire was obtained in the same manner as in Example 1 except that the protrusions were arranged in the rotational direction at intervals.

[Comparative Example 1]
Comparative Example 1 is a conventional lug-equipped tire having no protrusions.

[Evaluation of burial in mud]
A prototype tire was mounted on an agricultural tractor. The rim was 24 × W11 and the tire air pressure was 100 kPa. In a test course simulating a wet field, a running test was carried out at a running speed of 3 km / h. The buried property of the prototype tire in the mud is evaluated by confirming whether or not the stack phenomenon occurs. The evaluation results are shown in Table 1 below. The ratio of the mass of moisture contained in the mud to the mass of mud in the test course is 25%.

  As Table 1 shows, in the tire with a lug of an Example, burial of mud is suppressed effectively. From this evaluation result, the superiority of the present invention is clear.

  The lug-equipped tire according to the present invention can be mounted on various agricultural machines and light civil engineering construction machines.

FIG. 1 is a side view showing a lug tire according to an embodiment of the present invention. FIG. 2 is a development view showing a part of the tire of FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a side view showing a tire with lugs according to another embodiment of the present invention. FIG. 5 is a development view showing a part of the tire of FIG. 4. 6 is a cross-sectional view taken along line VI-VI in FIG.

Explanation of symbols

2, 42 ... Tire 4, 44 ... Tread 6, 46 ... Sidewall 8, 48 ... Bead 10, 50 ... Carcass 12, 52 ... Belt 14, 54 ... Projection 16 ... Main body 18, 56 ... Lug 20 ... Core 22 ... Apex 24 ... First carcass ply 26 ... Second carcass ply 28 ... Belt ply 30,58 ...・ Side surface 32, 64 ... tip 34, 60 ... outer surface 36, 66 ... root 38, 68 ... top surface 40 ... heel 62 ... side surface

Claims (5)

A tread comprising a main body and a number of lugs protruding substantially outward in the radial direction from the main body;
A protrusion protruding outward in the axial direction from the side surface,
This lug is arranged alternately left and right in the rotation direction,
The tip of this protrusion is located radially inward from the base of this lug,
A lug-equipped tire in which a ratio of a projection length of the protrusion from the axial maximum width of the lug to the axial maximum width of the lug is 0.05 or more and 0.15 or less. The outer surface located on the radially outer side of the protrusion is flat in a cross section along the radial direction,
The tire according to claim 1, wherein an angle formed by the outer surface with respect to the equator plane is 90 ° or more and 150 ° or less.   The tire according to claim 1 or 2, wherein a ratio of a length in a radial direction from a top surface of the lug to a tip of the protrusion with respect to a cross-sectional height is 0.60 or less.   The tire according to any one of claims 1 to 3, wherein a tip of the protrusion is continuous in a rotation direction. The tire according to any one of claims 1 to 3, wherein the protrusions are arranged in the rotational direction at intervals.

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