Non-pneumatic tire

Abstract

To provide a non-pneumatic tire configured so that strength of a connection site between an inner annular part and connection parts is enhanced to improve durability of the connection part, while securing a distance between the connection parts, at the inner annular part side.SOLUTION: A non-pneumatic tire 1 comprises an outer annular part 2 having a tread 5, an inner annular part 3 provided at inside the outer annular part 2, and a connection part 4 provided along a tire circumferential direction D to connect the outer annular part 2 to the inner annular part 3. The connection part 4 is configured so that a first connection part 41 extended from one side Y1 in a tire width direction Y of the outer annular part 2 toward the other side Y2 in the tire width direction Y of the inner annular part 3 and a second connection part 42 extended from the other side Y2 in the tire width direction of the outer annular part 2 toward the one side Y1 in the tire width direction Y of the inner annular part 3 are alternately arranged along the tire circumferential direction D. Thicknesses along the tire circumferential direction D of the connection part 4 are smaller in the inner annular part 3 side than in the outer annular part 2 side, and widths along the tire width direction Y of the connection part 4 are larger in the inner annular part 3 side than in the outer annular part 2 side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a non-pneumatic tire.

Background Art

[0002] In recent years, non-pneumatic tires that do not have problems such as punctures have been known (see, for example, Patent Document 1). Generally, a non-pneumatic tire has a structure in which a space between an outer annular portion and an inner annular portion provided concentrically inside the outer annular portion is connected by a plurality of plate-like connecting portions arranged in the tire circumferential direction. When a non-pneumatic tire receives a load from a vehicle, a compressive force acts on the connecting portions arranged in the contact area, causing them to bend and deform.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a non-pneumatic tire, the distance between adjacent connecting portions in the tire circumferential direction is large on the outer annular portion side and small on the inner annular portion side due to the difference in the circumferences of the outer annular portion and the inner annular portion. Therefore, as the number of connecting portions increases, it becomes difficult to ensure the distance between adjacent connecting portions. On the other hand, if the thickness of the connecting portions along the tire circumferential direction is made smaller on the inner annular portion side than on the outer annular portion side in order to ensure the distance between adjacent connecting portions, the strength of the connecting portions differs between the connection site with the outer annular portion and the connection site with the inner annular portion, resulting in a decrease in the durability of the connecting portions and a risk of breakage of the connecting portions when repeated stress is applied during tire rolling. Therefore, a conventional non-pneumatic tire has a problem of improving the strength of the connection site between the inner annular portion and the connecting portions while ensuring the distance between adjacent connecting portions on the inner annular portion side and improving the durability of the connecting portions.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a non-pneumatic tire capable of improving the strength of the connection portion between the inner annular portion and the connecting portion and improving the durability of the connecting portion while ensuring the distance between adjacent connecting portions on the inner annular portion side.

Means for Solving the Problems

[0006] The present invention is a non-pneumatic tire including an outer annular portion having a tread on the outer periphery, an inner annular portion provided inside the outer annular portion, and a connecting portion that connects the outer annular portion and the inner annular portion and is provided along the tire circumferential direction. The connecting portion includes a first connecting portion extending from one side in the tire width direction of the outer annular portion toward the other side in the tire width direction of the inner annular portion, and a second connecting portion extending from the other side in the tire width direction of the outer annular portion toward the one side in the tire width direction of the inner annular portion, which are alternately arranged along the tire circumferential direction. The thickness of the connecting portion along the tire circumferential direction is smaller on the inner annular portion side than on the outer annular portion side, and the width of the plurality of connecting portions along the tire width direction is larger on the inner annular portion side than on the outer annular portion side.

Effects of the Invention

[0007] According to the present invention, it is possible to provide a non-pneumatic tire capable of improving the strength of the connection portion between the inner annular portion and the connecting portion and improving the durability of the connecting portion while ensuring the distance between adjacent connecting portions on the inner annular portion side.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing a non-pneumatic tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 3 is a cross-sectional view taken along line B-B in FIG. 2. The non-pneumatic tire 1 includes an outer annular portion 2, an inner annular portion 3 provided concentrically inside the outer annular portion 2, and a plurality of connecting portions 4 that connect the outer annular portion 2 and the inner annular portion 3 and are provided independently along the tire circumferential direction D. A tread 5 is provided on the outer periphery of the outer annular portion 2. The tread 5 is provided with a tread pattern similar to that of a conventional pneumatic tire.

[0010] First, the outer annular portion 2 and the inner annular portion 3 will be described. Hereinafter, the thickness of the outer annular portion 2 and the inner annular portion 3 refers to the plate thickness in the direction along the tire radial direction X shown in FIGS. 1 and 2. The width of the outer annular portion 2 and the inner annular portion 3 refers to the width in the direction along the tire width direction Y shown in FIG. 2.

[0011] The outer annular portion 2 has a constant thickness in the circumferential direction and the width direction from the viewpoint of improving uniformity. The thickness of the outer annular portion 2 is not particularly limited, but from the viewpoints of sufficiently transmitting the force from the connecting portion 4 and achieving weight reduction and improved durability, it is preferably 2% or more and 7% or less of the tire cross-sectional height H shown in FIG. 2, and more preferably 2% or more and 5% or less.

[0012] The inner diameter of the outer annular portion 2 is appropriately determined according to the application and the like. For example, when assuming replacement of a general pneumatic tire, the inner diameter of the outer annular portion 2 can be 420 mm or more and 750 mm or less.

[0013] The width of the outer annular portion 2 is appropriately determined according to the intended use and the like. For example, when assuming the replacement of a general pneumatic tire, the width of the outer annular portion 2 can be 100 mm or more and 300 mm or less.

[0014] From the viewpoint of improving uniformity, the inner annular portion 3 has a constant thickness in the circumferential direction and the width direction. Although not shown, the inner circumferential surface of the inner annular portion 3 may be provided with unevenness or the like for maintaining fitting properties for mounting to an axle or a rim. The thickness of the inner annular portion 3 is not particularly limited, but from the viewpoints of sufficiently transmitting force to the connecting portion 4 and achieving weight reduction and improved durability, it is preferably 2% or more and 7% or less of the tire cross-sectional height H shown in FIG. 2, and more preferably 3% or more and 6% or less.

[0015] The inner diameter of the inner annular portion 3 is appropriately determined according to the dimensions of the rim or axle to which the non-pneumatic tire 1 is to be mounted. For example, when assuming the replacement of a general pneumatic tire, the inner diameter of the inner annular portion 3 can be 250 mm or more and 500 mm or less.

[0016] The width of the inner annular portion 3 is appropriately determined according to the intended use, the length of the axle, and the like. For example, when assuming the replacement of a general pneumatic tire, the width of the inner annular portion 3 can be 100 mm or more and 300 mm or less.

[0017] In the non-pneumatic tire 1, the connecting portion 4 is a member that functions as a spoke for connecting the outer annular portion 2 and the inner annular portion 3 so as to maintain a certain interval. A plurality of connecting portions 4 are arranged independently at regular intervals along the tire circumferential direction D, and as shown in FIG. 1, when the non-pneumatic tire 1 in the unloaded state is viewed from the front in the direction along the tire rotation axis, they extend linearly in the radial direction along the tire radial direction X.

[0018] The connecting part 4 is formed of an elastic material. The elastic material refers to a material that, when a tensile test is performed in accordance with JIS K7321, has a tensile modulus calculated from the tensile stress at 10% elongation of 100 MPa or less. Specifically, from the viewpoint of imparting appropriate rigidity while ensuring sufficient durability, the tensile modulus is preferably 5 MPa or more and 100 MPa or less, and more preferably 7 MPa or more and 50 MPa or less.

[0019] Examples of the elastic material used as the base material of the connecting part 4 include thermoplastic elastomers, crosslinked rubbers, and other resins.

[0020] Examples of the thermoplastic elastomer include polyester elastomer, polyolefin elastomer, polyamide elastomer, polystyrene elastomer, polyvinyl chloride elastomer, polyurethane elastomer, and the like.

[0021] As the rubber material constituting the crosslinked rubber, either natural rubber or synthetic rubber can be used. Examples of the synthetic rubber include styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IIR), nitrile rubber (NBR), hydrogenated nitrile rubber (hydrogenated NBR), chloroprene rubber (CR), ethylene-propylene rubber (EPDM), fluororubber, silicone rubber, acrylic rubber, urethane rubber, and the like. These rubber materials may be used in combination of two or more as necessary.

[0022] Examples of the other resins include thermoplastic resins and thermosetting resins. Examples of the thermoplastic resins include polyethylene resin, polystyrene resin, polyvinyl chloride resin, and the like. Examples of the thermosetting resins include epoxy resin, phenol resin, polyurethane resin, silicone resin, polyimide resin, melamine resin, and the like.

[0023] Among the above elastic materials, polyurethane resin is preferably used for the connecting portion 4 from the viewpoints of molding, workability, and cost. Note that a foamed material can also be used as the elastic material. That is, it is possible to use a foamed material of the above-mentioned thermoplastic elastomer, crosslinked rubber, or other resin. Further, when the outer annular portion 2 and the inner annular portion 3 are made of resin, the connecting portion 4 may be integrally formed using the same resin material as the outer annular portion 2 and the inner annular portion 3.

[0024] In the connecting portion 4, the first connecting portion 41 and the second connecting portion 42 are alternately arranged along the tire circumferential direction D. As shown in FIG. 2, the first connecting portion 41 extends from one side Y1 in the tire width direction Y of the outer annular portion 2 toward the other side Y2 in the tire width direction Y of the inner annular portion 3. On the other hand, the second connecting portion 42 extends from the other side Y2 in the tire width direction Y of the outer annular portion 2 toward the one side Y1 in the tire width direction Y of the inner annular portion 3. The first connecting portion 41 and the second connecting portion 42 adjacent to each other in the tire circumferential direction D are arranged so as to intersect in a substantially X shape when viewed from the tire circumferential direction D. The first connecting portion 41 and the second connecting portion 42 viewed from the tire radial direction X extend in a direction parallel to the tire width direction Y and perpendicular to the tire equatorial plane S.

[0025] As shown in FIG. 2, the first connecting portion 41 and the second connecting portion 42 viewed from the tire circumferential direction D have the same shape that is symmetric with respect to the tire equatorial plane S. Therefore, the first connecting portion 41 will be used to describe the specific shape of each connecting portion 4. The tire equatorial plane S is a plane perpendicular to the tire rotation axis (tire meridian) and located at the center in the tire width direction Y.

[0026] The connecting part 4 is formed in a long plate shape that extends obliquely from the outer annular part 2 toward the inner annular part 3. As shown in FIGS. 2 and 3, the connecting part 4 has a plate thickness T smaller than the plate width W, and the plate thickness direction PT faces the tire circumferential direction D. That is, the connecting part 4 is formed in a plate shape that extends in the tire radial direction X and the tire width direction Y. Note that the plate thickness T of the connecting part 4 is the thickness of the connecting part 4 along the tire circumferential direction D. The plate width W of the connecting part 4 is the width of the connecting part 4 in the direction along the tire width direction Y. Since the connecting part 4 is such a long plate shape, even if the plate thickness T is made thin, by setting the plate width W wide, the durability of the connecting part 4 when the plate thickness T is thin can be improved. Furthermore, by increasing the number of the first connecting part 41 and the second connecting part 42 while making the plate thickness T thin, the gap between the adjacent connecting parts 4, 4 in the tire circumferential direction D can be made small while maintaining the rigidity of the entire tire. Thereby, the ground pressure dispersion during tire rolling can be reduced. The more detailed configuration of the plate thickness T and the plate width W of this connecting part 4 will be described later.

[0027] As shown in FIG. 2, the connecting part 4 has a shape in which the connection part 401 with the outer annular part 2 and the connection part 402 with the inner annular part 3 each gently expand along the tire width direction Y. The connection part 401 of the first connecting part 41 with the outer annular part 2 is provided over a region that is half of the outer annular part 2 in the tire width direction.

[0028] That is, one side Y1 of the connection part 401 of the first connecting part 41 extends to the end 2a on one side Y1 of the outer annular part 2. The other side Y2 of the connection part 401 of the first connecting part 41 extends to the tire equatorial plane S disposed at the center of the outer annular part 2 in the tire width direction. The other side Y2 of the connection part 401 of the first connecting part 41 extends to the end 3b on the other side Y2 of the inner annular part 3. One side Y1 of the connection part 402 of the first connecting part 41 extends to the tire equatorial plane S disposed at the center of the inner annular part 3 in the tire width direction.

[0029] Similarly, the other side Y2 of the connection part 401 of the second connecting part 42 extends to the end 2b of the other side Y2 of the outer annular part 2. One side Y1 of the connection part 401 of the second connecting part 42 extends to the tire equatorial plane S disposed at the center in the tire width direction of the outer annular part 2. One side Y1 of the connection part 402 of the second connecting part 42 extends to the end 3a of one side Y1 of the inner annular part 3. The other side Y2 of the connection part 402 of the second connecting part 42 extends to the tire equatorial plane S disposed at the center in the tire width direction of the inner annular part 3.

[0030] The pitch p between the first connecting part 41 and the second connecting part 42 adjacent to each other in the tire circumferential direction D is preferably constant and small in the tire circumferential direction D. Specifically, the pitch p is preferably 1 mm or more and 10 mm or less, and more preferably 1 mm or more and 5 mm or less. When the pitch p is larger than 10 mm, the contact pressure tends to be non-uniform in the tire circumferential direction D, and there is a possibility of generating vehicle exterior noise.

[0031] The number of the connecting parts 4 provided in the non-pneumatic tire 1 is preferably 80 or more and 300 or less, and more preferably 100 or more and 200 or less, from the viewpoints of sufficiently supporting the load from the vehicle while achieving weight reduction, improvement in power transmission, and durability. FIG. 1 shows an example in which 50 first connecting parts 41 and 50 second connecting parts 42 are provided respectively.

[0032] As shown in FIG. 4, the plate thickness T of the connecting part 4 is different between the outer annular part 2 side and the inner annular part 3 side. Specifically, the plate thickness Tr of the connecting part 4 on the inner annular part 3 side is smaller than the plate thickness Tt of the connecting part 4 on the outer annular part 2 side. Therefore, even if the plate thickness of the connecting part 4 is increased as a whole, or the number of the connecting parts 4 along the tire circumferential direction D is increased, the distance between the adjacent connecting parts 4, 4 in the tire circumferential direction D can be ensured on the inner annular part 3 side. Specific plate thicknesses Tt and Tr are not limited. For example, the plate thickness Tt of the connecting part 4 on the outer annular part 2 side can be 18% or more and 22% or less of the tire section height H, and the plate thickness Tr of the connecting part 4 on the inner annular part 3 side can be 13% or more and 17% or less of the tire section height H.

[0033] As shown in FIG. 2, the plate width W of the connecting portion 4 is different between the outer annular portion 2 side and the inner annular portion 3 side. Specifically, the plate width Wr on the inner annular portion 3 side of the connecting portion 4 is larger than the plate width Wt on the outer annular portion 2 side. Therefore, even if the plate thickness Tr on the inner annular portion 3 side is smaller than the plate thickness Tt on the outer annular portion 2 side, the difference in the cross-sectional area of each when the connecting portion 4 is cut by a plane orthogonal to the tire diameter direction X on the outer annular portion 2 side and the inner annular portion 3 side can be reduced. As a result, the strength of the connection portion between the inner annular portion 3 side of the connecting portion 4 where the plate thickness Tr is small and the inner annular portion 3 can be improved, and the durability of the connecting portion 4 can be improved.

[0034] Note that the plate width Wt on the outer annular portion 2 side and the plate width Wr on the inner annular portion 3 side of the connecting portion 4 are the plate widths of the portions that are bent and deformed when a load is applied to the connecting portion 4, respectively, and are the plate widths at positions as close as possible to the outer annular portion 2 and the inner annular portion 3. As shown in FIG. 2, when the connection portion 401 between the connecting portion 4 and the outer annular portion 2 and the connection portion 402 between the connecting portion 4 and the inner annular portion 3 are in a shape that spreads in the tire width direction Y, the plate width Wt on the outer annular portion 2 side of the connecting portion 4 is at a position on the inner annular portion 3 side from the connection portion 401 and is the width of the portion adjacent to the connection portion 401. This portion is located on the outer annular portion 2 side of the tire cross-sectional height H / 2. Also, the plate width Wr on the inner annular portion 3 side of the connecting portion 4 is at a position on the outer annular portion 2 side from the connection portion 402 and is the width of the portion adjacent to the connection portion 402. This portion is located on the inner annular portion 3 side of the tire cross-sectional height H / 2.

[0035] The plate width W of the connecting portion 4 shown in FIG. 2 gradually increases from the outer annular portion 2 side toward the inner annular portion 3 side. Specifically, the inner line 4a and the outer line 4b in the tire width direction Y of the connecting portion 4 are formed so as to spread in the tire width direction Y at a constant ratio from the connection portion 401 side with the outer annular portion 2 toward the connection portion 402 side with the inner annular portion 3. According to this, the cross-sectional area of the connecting portion 4 can be made substantially uniform over the entire tire cross-sectional height H.

[0036] Note that when viewing the connecting portion 4 extending obliquely from the outer annular portion 2 toward the inner annular portion 3 in the tire circumferential direction D, as shown in FIG. 2, the inner line 4a is a line on the side where the intersection angle θ1 with the outer annular portion 2 becomes an obtuse angle, and the outer line 4b is defined as a line on the side where the intersection angle θ2 with the outer annular portion 2 becomes an acute angle. Therefore, in the first connecting portion 41 shown in FIG. 2, the inner line 4a is a line on the other side Y2 in the tire width direction Y, and the outer line 4b is a line on one side Y1 in the tire width direction Y. In the second connecting portion 42, the inner line 4a is a line on one side Y1 in the tire width direction Y, and the outer line 4b is a line on the other side Y2 in the tire width direction Y.

[0037] As shown in FIG. 5, the plate width W of the connecting portion 4 may gradually increase from the middle portion in the tire diameter direction X in the connecting portion 4 toward the inner annular portion 3 side. In the connecting portion 4 shown in FIG. 5, the plate width Wt on the outer annular portion 2 side is a constant width compared to the position of half of the tire cross-sectional height H, while the plate width Wr on the inner annular portion 3 side is formed to increase as it goes toward the inner annular portion 3 side from the position of half of the tire cross-sectional height H. According to this, it is possible to prevent the breakage of the connecting portion 4 on the inner annular portion 3 side without impairing the ease of deformation of the connecting portion 4 on the outer annular portion 2 side.

[0038] As shown in FIG. 6, the plate width W of the connecting portion 4 may increase stepwise from the outer annular portion 2 side toward the inner annular portion 3 side. In the connecting portion 4 shown in FIG. 6, by forming only the inner line 4a on the inner annular portion 3 side of the connecting portion 4 in a stepped manner from more than half of the tire cross-sectional height H, the plate width Wr on the inner annular portion 3 side of the connecting portion 4 increases stepwise. However, the outer line 4b may also be formed in a stepped manner in the same way. Further, by forming the inner line 4a and the outer line 4b of the connecting portion 4 in a stepped manner over the entire tire cross-sectional height H, the plate width W of the connecting portion 4 may be increased stepwise.

[0039] In addition, when increasing the plate width Wr of the connecting portion 4 on the inner annular portion 3 side, it is not limited to changing the angles and shapes of both the inner line 4a and the outer line 4b of the connecting portion 4. It is also possible to change only the angle and shape of either one of the inner line 4a and the outer line 4b. For example, in FIG. 6, without changing the shape of the outer line 4b of the connecting portion 4, the inner line 4a is formed in a stepped shape, thereby increasing the plate width Wr of the connecting portion 4 on the inner annular portion 3 side. Conversely, without changing the shape of the inner line 4a of the connecting portion 4, the plate width Wr of the connecting portion 4 on the inner annular portion 3 side may be increased.

[0040] According to the non-pneumatic tire 1 of the present embodiment, the following effects are obtained.

[0041] (1) The non-pneumatic tire 1 according to the present embodiment includes an outer annular portion 2 having a tread 5 on the outer periphery, an inner annular portion 3 provided inside the outer annular portion 2, and a connecting portion 4 that connects the outer annular portion 2 and the inner annular portion 3 and is provided along the tire circumferential direction D. The connecting portion 4 includes a first connecting portion 41 extending from one side Y1 in the tire width direction Y of the outer annular portion 2 toward the other side Y2 in the tire width direction Y of the inner annular portion 3, and a second connecting portion 42 extending from the other side Y2 in the tire width direction Y of the outer annular portion 2 toward the one side Y1 in the tire width direction Y of the inner annular portion 3, which are alternately arranged along the tire circumferential direction D. The thickness T of the connecting portion 4 along the tire circumferential direction D is smaller on the inner annular portion 3 side than on the outer annular portion 2 side, and the width W of the connecting portion 4 along the tire width direction Y is larger on the inner annular portion 3 side than on the outer annular portion 2 side. Thus, even if the overall plate thickness T of the connecting portion 4 is increased, or the number of the connecting portions 4 along the tire circumferential direction D is increased, the distance between the adjacent connecting portions 4, 4 in the tire circumferential direction D can be ensured on the inner annular portion 3 side. Also, even if the plate thickness Tr on the inner annular portion 3 side is smaller than the plate thickness Tt on the outer annular portion 2 side, the difference in the cross-sectional area of each when the connecting portion 4 is cut by a plane orthogonal to the tire radial direction X on the outer annular portion 2 side and the inner annular portion 3 side can be reduced. Thereby, the strength of the connection portion between the inner annular portion 3 with a small plate thickness Tr and the connecting portion 4 can be improved, and the durability of the connecting portion 4 can be improved.

[0042] (2) In the non-pneumatic tire 1 according to the present embodiment, the width W along the tire width direction Y of the connecting portion 4 may gradually or stepwise increase from the outer annular portion 2 side toward the inner annular portion 3 side. According to this, the cross-sectional area of the connecting portion 4 can be made substantially uniform over the entire tire cross-sectional height H.

[0043] (3) In the non-pneumatic tire 1 according to the present embodiment, the width W along the tire width direction Y of the connecting portion 4 may gradually or stepwise increase from the middle portion in the tire radial direction X in the connecting portion 4 toward the inner annular portion 3 side, and may have a constant width from the middle portion toward the outer annular portion 2 side. According to this, it is possible to prevent the connecting portion 4 on the inner annular portion 3 side from breaking without impairing the ease of deformation of the connecting portion 4 on the outer annular portion 2 side.

Explanation of reference numerals

[0044] 1 Non-pneumatic tire 2 Outer annular portion 3 Inner annular portion 4 Connecting portion 41 First connecting portion 42 Second connecting portion 5 Tread D Tire circumferential direction T Plate thickness Tt Plate thickness on the outer annular portion side Tr Plate thickness on the inner annular portion side W Plate width Wt Plate width on the outer annular portion side Wr Plate width on the inner annular portion side X Tire radial direction Y Tire width direction Y1 One side Y2 The other side

Claims

Claim 1 an outer annular portion having a tread on the outer periphery, an inner annular portion provided inside the outer annular portion, a non-pneumatic tire comprising a connecting portion that connects the outer annular portion and the inner annular portion and is provided along the tire circumferential direction, the connecting portion includes a first connecting portion extending from one side in the tire width direction of the outer annular portion toward the other side in the tire width direction of the inner annular portion, and a second connecting portion extending from the other side in the tire width direction of the outer annular portion toward the one side in the tire width direction of the inner annular portion, which are alternately arranged along the tire circumferential direction, and a connection portion with the outer annular portion has a shape that widens in the tire width direction toward the outer annular portion, the thickness of the connecting portion along the tire circumferential direction is smaller on the inner annular portion side than on the outer annular portion side, the width of the connecting portion along the tire width direction is larger on the inner annular portion side than on the outer annular portion side, and is a constant width from a portion adjacent to the connection portion to a position of 1 / 2 of the tire cross-sectional height, and is formed to gradually or stepwise increase from the position of 1 / 2 of the tire cross-sectional height toward the inner annular portion side. A non-pneumatic tire.

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