JP7647429B2 - Solid Tire - Google Patents

Description

This specification discloses a solid tire.

Solid tires (also called solid tires) are primarily used on transport equipment in production facilities and industrial vehicles such as forklifts. Solid tires have a wheel and a tread attached to the wheel. The typical material for the tread is a rubber composition.

When a solid tire is subjected to a large load, the tread flexes. This flexing tends to cause stress concentration near the axially outer end of the tread's interface with the wheel (the edge of the tread's interface). Stress concentration at the edge of the tread's interface can cause the edge of the tread's interface to peel off from the wheel. JP 2005-349872 A discloses a study on a solid tire that alleviates stress concentration at the edge of the tread's interface.

JP 2005-349872 A

Solid tires are required to effectively prevent the edge of the tread joint from peeling off from the wheel.

The inventors' intention is to provide a solid tire in which the edge of the tread joint surface is prevented from peeling off from the wheel.

A preferred solid tire comprises an annular wheel and a tread having a tread surface located radially outward of the wheel and in contact with the road surface, the wheel having a side surface, an outer peripheral surface, and an inclined surface located between the side surface and the outer peripheral surface and inclined radially outward as it approaches the axially inward, and the ratio (Te/T) of the radial thickness Te at the axially outer end of the tread to the radial thickness T at the equator is 0.070 or more and 0.25 or less.

In this solid tire, the concentration of stress at the joint edge of the tread is effectively mitigated by providing an inclined surface on the wheel and by setting the ratio (Te/T) of the radial thickness Te at the axially outer end of the tread to the radial thickness T at the equator to 0.070 or more and 0.25 or less. In this tire, separation of the joint edge of the tread from the wheel is suppressed.

FIG. 1 is a perspective view showing a solid tire according to one embodiment. FIG. 2 is a cross-sectional view showing a cross section perpendicular to the circumferential direction of the tire shown in FIG. FIG. 3 is an enlarged cross-sectional view of a portion of FIG. FIG. 4 is a cross-sectional view showing a solid tire according to another embodiment.

A preferred embodiment will be described in detail below, with reference to the drawings as appropriate.

Figure 1 is a perspective view showing a solid tire 2. In Figure 1, the arrow X indicates the axial direction of the tire 2, and the arrow A indicates the circumferential direction of the tire 2. Figure 2 is a cross-sectional view showing a cross section perpendicular to the circumferential direction of the tire 2 in Figure 1. In Figure 2, the arrow X indicates the axial direction of the tire 2, the arrow Y indicates the radial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. In Figure 2, the dashed dotted line CL represents the equatorial plane of the tire 2. This tire 2 does not have a cavity for putting air in. This tire 2 is a solid tire 2. As shown in Figures 1 and 2, this tire 2 has a tread 4 and a wheel 6.

The tread 4 has an annular shape. The tread 4 is attached to the radially outer side of the wheel 6. The tread 4 is made of crosslinked rubber that has excellent wear resistance and grip. Examples of base rubber for the tread 4 include natural rubber (NR), polyisoprene (IR), polybutadiene (BR), and urethane rubber (U). The material for the tread 4 may be a thermoplastic elastomer.

The tread 4 has a tread surface 8 that comes into contact with the road surface, a joint surface 10 that comes into contact with the wheel 6, and a pair of side surfaces 12. Each side surface 12 is located between the tread surface 8 and the joint surface 10. The tread surface 8, the joint surface 10, and the side surfaces 12 each extend in the circumferential direction. In the embodiment of FIG. 1, grooves 14 are cut into the tread surface 8. The grooves 14 form a tread pattern. The grooves 14 do not have to be cut into the tread surface 8.

Figure 3 shows an enlarged view of the vicinity of the axially outer end of the joint surface 10. In Figure 3, the reference character P1 represents the radially inner end of the side surface 12 of the tread 4. The reference character P1 also represents the axially outer end of the joint surface 10. In this specification, the position represented by the reference character P1 is referred to as the "end point P1."

As shown in FIG. 3, each side surface 12 has an end portion 16 and a curved portion 18. The end portion 16 extends radially from an end point P1. The end portion 16 extends radially from the axially outer end of the joining surface 10. The end portion 16 has a straight shape in a cross section perpendicular to the circumferential direction. The curved portion 18 extends from an outer end 19 of the end portion 16. The curved portion 18 is inclined so as to extend radially outward as it extends axially inward. In this embodiment, the curved portion 18 has an inwardly convex arc shape in a cross section perpendicular to the circumferential direction.

In FIG. 3, the double-headed arrow Te represents the radial thickness of the tread 4 at the axially outer end. In detail, the thickness Te is the distance in the radial direction between the end point P1 and the outer end 19 of the end portion 16. In FIG. 2, the double-headed arrow T represents the radial thickness of the tread 4 at the equator. In this tire 2, the ratio of the thickness Te to the thickness T (Te/T) is 0.070 or more and 0.25 or less.

The wheel 6 has an annular shape. The wheel 6 is typically made of metal. Preferred materials for the wheel 6 include steel and aluminum alloy. The wheel 6 may also be made of synthetic resin.

The wheel 6 has an outer peripheral surface 20, an inner peripheral surface 22, a pair of side surfaces 24, and a pair of inclined surfaces 26. The outer peripheral surface 20 is covered by the tread 4. The outer peripheral surface 20 is in contact with the joint surface 10 of the tread 4. The inner peripheral surface 22 forms the inner peripheral surface of the tire 2. The outer peripheral surface 20, the inner peripheral surface 22, the side surfaces 24, and the inclined surfaces 26 each extend in the circumferential direction.

As shown in FIG. 2, each side surface 24 extends radially from the axially outer end of the inner circumferential surface 22. As shown in FIG. 3, the side surface 24 is continuous with the end 16 of the tread 4. That is, the end point P1 coincides with the radially outer end of the side surface 24 of the wheel 6. The side surface 24 is connected to the end 16 in a straight line.

Each inclined surface 26 is located between the corresponding side surface 24 and the outer peripheral surface 20. The inclined surface 26 extends from an end point P1. That is, the end point P1 is the axially outer end of the inclined surface 26. The inclined surface 26 is inclined so as to move radially outward as it moves axially inward. As shown in FIG. 3, in this embodiment, in a cross section perpendicular to the circumferential direction, the inclined surface 26 has an outwardly convex arc shape.

In FIG. 3, the reference symbol P2 represents the axially inner end of the inclined surface 26. The reference symbol P2 also represents the axially outer end of the outer peripheral surface 20. In this specification, the position represented by the reference symbol P2 is referred to as the "end point P2." At the end point P2, the inclined surface 26 connects with the outer peripheral surface 20. The inclined surface 26 is covered by the tread 4. The inclined surface 26 is in contact with the joint surface 10 of the tread 4.

The effects of this embodiment are explained below.

In the solid tire 2 according to the present disclosure, the wheel 6 has an inclined surface 26 located between the side surface 24 and the outer peripheral surface 20, which is inclined so as to move radially outward as it moves axially inward. This inclined surface 26 prevents the concentration of stress applied to the vicinity of the axial outer end of the joint surface 10 of the tread 4 (the joint surface end of the tread 4). Furthermore, in this solid tire, the ratio (Te/T) of the thickness Te to the thickness T is 0.070 or more and 0.25 or less. By providing the inclined surface 26 on the wheel 6 and appropriately setting the thickness Te of the tread 4 at the position in contact with this inclined surface 26, the concentration of stress at the joint surface end of the tread 4 is more effectively prevented. In this solid tire 2, the joint surface end of the tread 4 is prevented from peeling off from the wheel 6.

The ratio (Te/T) is more preferably 0.10 or more. By making the ratio (Te/T) 0.10 or more, the tread 4 has a thickness at the axially outer end that can withstand the load of stress. In this solid tire 2, the end of the joint surface of the tread 4 is more effectively prevented from peeling off from the wheel 6. From this viewpoint, the ratio (Te/T) is more preferably 0.14 or more. The ratio (Te/T) is more preferably 0.21 or less. By making the ratio (Te/T) 0.21 or less, the concentration of stress applied to the end of the joint surface of the tread 4 is more effectively alleviated. In this solid tire 2, the end of the joint surface of the tread 4 is more effectively prevented from peeling off from the wheel 6. From this viewpoint, the ratio (Te/T) is more preferably 0.18 or less.

In FIG. 3, the double-headed arrow Wr represents the radial width of the inclined surface 26. More specifically, the width Wr is the radial distance between the end points P1 and P2. The ratio (Wr/T) of the width Wr to the thickness T is preferably 0.050 or greater. By setting the ratio (Wr/T) to 0.050 or greater, the inclined surface 26 effectively reduces the concentration of stress at the end of the joint surface of the tread 4. From this perspective, the ratio (Wr/T) is more preferably 0.060 or greater, and even more preferably 0.080 or greater.

Increasing the ratio (Wr/T) reduces the radial thickness at the axial ends of the wheel 6. This may affect the durability of the wheel 6. To ensure the durability of the wheel 6, it may be possible to increase the radial thickness of the entire wheel 6. However, this may affect the cost of the wheel 6.

The ratio (Wr/T) is preferably 0.15 or less. By keeping the ratio (Wr/T) at 0.15 or less, it is possible to maintain excellent durability while suppressing increases in costs. From this perspective, the ratio (Wr/T) is more preferably 0.14 or less, and even more preferably 0.12 or less.

In FIG. 3, the double-headed arrow Wa represents the axial width of the inclined surface 26. In detail, the width Wa is the axial distance between the end points P1 and P2. The ratio (Wa/Wr) of the width Wa to the width Wr is preferably 0.50 or more. By setting the ratio (Wa/Wr) to 0.50 or more, the portion of the tread 4 that is present axially outside the inclined surface 26 has a size that can withstand the stress applied. In this solid tire 2, the end of the joint surface of the tread 4 is prevented from peeling off from the wheel 6. From this viewpoint, the ratio (Wa/Wr) is more preferably 0.60 or more, and even more preferably 0.80 or more. The ratio (Wa/Wr) is preferably 1.5 or less. By setting the ratio (Wa/Wr) to 1.5 or less, the inclined surface 26 effectively relieves the concentration of stress on the end of the joint surface of the tread 4. From this viewpoint, the ratio (Wa/Wr) is more preferably 1.4 or less, and even more preferably 1.2 or less.

In FIG. 3, the symbol V represents an imaginary line that passes through the end point P2 and extends in the radial direction. The double-headed arrow Ti represents the radial thickness of the tread 4 at the end point P2. The thickness Ti is the thickness of the tread 4 measured along the imaginary line V.

The ratio (Ti/Te) of the thickness Ti to the thickness Te is preferably 0.70 or more. By setting the ratio (Ti/Te) to 0.70 or more, the tread 4 has a thickness that can withstand the stress applied at the axial inner end of the inclined surface 26. In this solid tire 2, the end of the joint surface of the tread 4 is prevented from peeling off from the wheel 6. From this viewpoint, the ratio (Ti/Te) is more preferably 0.90 or more, and even more preferably 1.1 or more. The ratio (Ti/Te) is preferably 2.0 or less. By setting the ratio (Ti/Te) to 2.0 or less, the concentration of the stress applied to the end of the joint surface of the tread 4 is effectively alleviated. In this solid tire 2, the end of the joint surface of the tread 4 is prevented from peeling off from the wheel 6. From this viewpoint, the ratio (Ti/Te) is more preferably 1.7 or less, and even more preferably 1.5 or less.

In FIG. 3, the arrow R indicates the radius of curvature of the curved portion 18. The radius of curvature R is preferably 10 mm or more. By making the radius of curvature R 10 mm or more, the concentration of stress applied to the joint surface end of the tread 4 is effectively alleviated. From this viewpoint, the radius of curvature R is more preferably 15 mm or more, and even more preferably 20 mm or more. The radius of curvature R is preferably 40 mm or less. By making the radius of curvature R 40 mm or less, the tread 4 has a thickness that can withstand the applied stress near the outer end in the axial direction. The tread 4 has excellent durability. From this viewpoint, the radius of curvature R is more preferably 35 mm or less, and even more preferably 30 mm or less.

Figure 4 is a cross-sectional view showing a solid tire 30 according to another embodiment. This tire 30 has a tread 32 and a wheel 34. The wheel 34 has an inclined surface 40 between an outer peripheral surface 36 and a side surface 38. In this tire 30, the shape of the inclined surface 40 of the wheel 34 is different from that of the tire 2 in Figure 3.

The inclined surface 40 is inclined so as to move radially outward as it moves axially inward. As shown in FIG. 4, in this embodiment, the inclined surface 40 is linear in a cross section perpendicular to the circumferential direction. The linear inclined surface 40 effectively relieves the concentration of stress applied to the joint surface end of the tread 32. In this solid tire 30, the joint surface end of the tread 32 is prevented from peeling off from the wheel 34.

In addition, in the solid tire 30 of the embodiment of FIG. 4, the preferred ranges of the ratios (Te/T), (Wr/T), (Wa/Wr), (Ti/Te), and the radius of curvature R are the same as those in the solid tire 2 of the embodiment of FIG. 3.

The effects of the solid tire according to the embodiment will be explained below, but the scope of the present specification should not be interpreted as being limited based on the description of the embodiment.

[Example 1]
A solid tire of Example 1 was obtained with the specifications shown in Table 1 below. The outer diameter of this tire measured at the equatorial plane was 267 mm, and the tread thickness T was 42 mm. The inner diameter of the wheel was 165 mm. The base rubber of the tread was natural rubber.

[Comparative Example 1]
In this tire, the wheel does not have an inclined surface. The side surface of the wheel is connected to the outer circumferential surface. The ratio (Te/T) of this tire is as shown in Table 1. Other than these, the tire of Comparative Example 1 was obtained in the same manner as Example 1.

[Comparative Example 2-3, Example 2-4]
Tires of Comparative Example 2-3 and Example 2-4 were obtained in the same manner as in Example 1 except that the ratio (Te/T) was as shown in Table 1.

[Example 5]
A tire of Example 5 was obtained in the same manner as in Example 1, except that the shape of the inclined surface was made to be an arc.

[Examples 6-7]
The tires of Examples 6 and 7 were obtained in the same manner as in Example 3, except that the values of the ratio (Wr/T), ratio (Wr/T), ratio (Ti/Te), radius R, and the shape of the inclined surface were as shown in Table 2.

[Example 8]
A tire of Example 8 was obtained in the same manner as in Example 1, except that the value of the ratio (Ti/Te), the value of the radius R, and the shape of the inclined surface were as shown in Table 2.

[Tread peeling]
This tire was mounted on the drive wheels of a vehicle (a 2.5 ton counterweight type forklift). The vehicle was loaded so that a load of 28.5 kN was applied to the tire. This vehicle was repeatedly driven in a slalom run on a flat asphalt road surface. The speed of the vehicle at this time was 8 km/h. The running time until peeling occurred at the end of the tread joint surface was measured. The results are shown in Table 1-2 on a scale of 1 to 10. The higher the value, the longer the running time. The higher the value, the more preferable it is.

As shown in Table 1-2, the tire of the embodiment has less tread separation than the tire of the comparison example. The superiority of this solid tire is clear from these evaluation results.

[Disclosure items]
The following section discloses preferred embodiments.

[Item 1]
A solid tire comprising: an annular wheel; and a tread having a tread surface located radially outward of the wheel and in contact with a road surface, the wheel having a side surface, an outer peripheral surface, and an inclined surface located between the side surface and the outer peripheral surface, the inclined surface inclining radially outward as it moves axially inward, the ratio (Te/T) of a radial thickness Te at an axially outer end of the tread to a radial thickness T at the equator being 0.070 or greater and 0.25 or less.

[Item 2]
2. The solid tire according to item 1, wherein a ratio (Wr/T) of a radial width Wr of the inclined surface to the thickness T is 0.050 or greater and 0.15 or less, and a ratio (Wa/Wr) of an axial width Wa of the inclined surface to the width Wr is 0.50 or greater and 1.5 or less.

[Item 3]
3. The solid tire according to item 1 or 2, wherein the inclined surface is linear in a cross section perpendicular to the circumferential direction.

[Item 4]
4. The solid tire according to any one of items 1 to 3, wherein a ratio (Ti/Te) of a radial thickness Ti of the tread at an axially inner end of the inclined surface to the thickness Te is 0.70 or greater and 2.0 or less.

[Item 5]
5. A solid tire according to any one of items 1 to 4, wherein the tread has a side surface, the side surface of the tread has an end portion extending radially from an inner end of the side surface and a curved portion extending from an outer end of the end portion, the curved portion having an inwardly convex arc shape in a cross section perpendicular to the circumferential direction, and a radius of curvature of the curved portion is 10 mm or more and 40 mm or less.

The solid tires described above can be mounted on conveying equipment in production lines and industrial vehicles.

2, 30: Solid tire 4, 32: Tread 6, 34: Wheel 8: Tread surface 10: Joint surface 12: Side surface of tread 14: Groove 16: End 18: Curved portion 20, 36: Outer peripheral surface 22: Inner peripheral surface 24, 38: Side surface of wheel 26, 40: Inclined surface

Claims (5)

The tire comprises an annular wheel and a tread located radially outward of the wheel and having a tread surface that contacts a road surface,
The wheel has a side surface, an outer circumferential surface, and an inclined surface located between the side surface and the outer circumferential surface, the inclined surface inclining toward the radially outward direction as it moves toward the axially inward direction,
The solid tire has a ratio (Te/T) of a radial thickness Te at an axially outer end of the tread to a radial thickness T at the equator of the tread, which is 0.070 or greater and 0.25 or less. a ratio (Wr/T) of a radial width Wr of the inclined surface to the thickness T is 0.050 or more and 0.15 or less,
2. The solid tire according to claim 1, wherein a ratio (Wa/Wr) of an axial width Wa of said inclined surface to said width Wr is equal to or greater than 0.50 and equal to or less than 1.5. The solid tire according to claim 1 or 2, wherein the inclined surface is linear in a cross section perpendicular to the circumferential direction. A solid tire according to any one of claims 1 to 3, wherein the ratio (Ti/Te) of the radial thickness Ti of the tread at the axially inner end of the inclined surface to the thickness Te is 0.70 or more and 2.0 or less. the tread has a side surface;
a side surface of the tread having an end portion extending radially from an inner end of the side surface and a curved portion extending from an outer end of the end portion;
5. The solid tire according to claim 1, wherein the curved portion has an inwardly convex arc shape in a cross section perpendicular to the circumferential direction, and the curved portion has a radius of curvature of 10 mm or more and 40 mm or less.

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