JP2013018462A - Non-pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-pneumatic tire which is used for a vehicle performing cornering with a camber angle, and which has improved durability by mitigating stress concentration of spokes.SOLUTION: The non-pneumatic tire T includes: an inner circular part 1; an outer circular part 3 having a tread face 6 which is provided in a concentric circle shape outside the inner circular part 1 and which has such a curvature that outer diameters decrease gradually from a center to both sides in the tire width direction; and a plurality of connection parts 4 and 5 for connecting the inner circular part 1 and the outer circular part 3. In a tire meridian cross part, an inner circumferential surface 7 of the outer circular part 3 is formed in a convex shape in which a center portion 7a in the tire width direction projects to inside in the tire diameter direction more than both side portions 7b.

Description

  The present invention includes an inner annular portion and a tread surface that is provided concentrically on the outer side of the inner annular portion and has a curvature such that the outer diameter gradually decreases from the center portion in the tire width direction toward both side portions. The present invention relates to a non-pneumatic tire including an outer annular portion that is provided and a plurality of connecting portions that connect the inner annular portion and the outer annular portion.

  The pneumatic tire has a load supporting function, a shock absorbing ability from the ground contact surface, and a transmission ability (acceleration, stop, change of direction) such as power. For this reason, many vehicles, particularly bicycles, motorcycles, automobiles, It is used in trucks.

  In particular, these capabilities greatly contributed to the development of automobiles and other motor vehicles. Furthermore, the impact absorbing ability of pneumatic tires is useful for medical equipment and electronic equipment transport carts and other applications.

  Conventional non-pneumatic tires include, for example, solid tires, spring tires, cushion tires, and the like, but do not have the superior performance of pneumatic tires. For example, solid tires and cushion tires support the load by compressing the contact portion, but this type of tire is heavy and stiff, and does not have the ability to absorb shock like a pneumatic tire. Further, in the non-pneumatic tire, it is possible to improve the cushioning property by increasing the elasticity, but there is a problem that the load supporting ability or the durability as the pneumatic tire has is deteriorated.

  Therefore, in Patent Document 1 below, for the purpose of developing a non-pneumatic tire having the same operating characteristics as a pneumatic tire, a reinforced annular band that supports a load applied to the tire, and the reinforced annular band, Non-pneumatic tires have been proposed that have a plurality of spokes that transmit load forces by tension with a wheel or hub. The non-pneumatic tire of Patent Document 1 has no fear of air leakage like a pneumatic tire, and there is no weight problem like a solid tire.

  However, the non-pneumatic tire described in Patent Document 1 has a substantially flat tread surface to be grounded, and is not suitable for a vehicle that is cornered with a camber. That is, in a non-pneumatic tire with a flat tread surface, the ground contact area with the camber attached approaches as much as zero, and the gripping force is greatly reduced to cause slipping.

  In view of this, a non-pneumatic tire having a tread surface having a curvature that gradually decreases in outer diameter from a central portion in the tire width direction toward both side portions has been developed for a vehicle that is cornered with a camber. However, as a result of repeated research by the present inventor, when the tread surface has a curvature, stress is concentrated in the central portion of the spoke in the radial direction and the width direction of the spoke, and the tire is quickly damaged by using the stress concentrated portion as a starting point. It was found that the durability was lowered.

Special Table 2005-500932 Publication

  SUMMARY OF THE INVENTION An object of the present invention is to provide a non-pneumatic tire that is used for a vehicle that is cornered with a camber and has improved durability by relaxing stress concentration of spokes.

The above object can be achieved by the present invention as described below.
That is, the non-pneumatic tire of the present invention is provided with a concentric circular shape on the inner annular portion and on the outer side of the inner annular portion so that the outer diameter gradually decreases from the center portion in the tire width direction toward both side portions. A non-pneumatic tire comprising an outer annular portion having a tread surface having a plurality of connecting portions that connect the inner annular portion and the outer annular portion, and in the tire meridian cross section, the inner circumference of the outer annular portion The surface is formed in a convex shape in which a central portion in the tire width direction protrudes inward in the tire radial direction from both side portions.

  In the case of a tread surface having a curvature such that the outer diameter gradually decreases from the center portion in the tire width direction toward both side portions, stress concentrates on the tire radial direction and the width direction center portion of the connecting portion (spoke). According to the present invention, the tire radial direction length of the connecting portion is such that the central portion in the tire width direction is shorter than the both side portions, so that stress concentration in the tire radial direction and the central portion in the width direction of the connecting portion is alleviated. Can do. Thereby, the early tire breakage based on the stress concentration portion can be prevented, and the durability of the non-pneumatic tire can be improved.

  In the non-pneumatic tire according to the present invention, the inner peripheral surface of the outer annular portion is preferably formed in an arcuate convex shape. By making the inner peripheral surface of the outer annular part an arc-shaped convex shape, the connection interface between the outer annular part and the connecting part becomes smooth, the adhesiveness between them is good, and the durability of the non-pneumatic tire can be further improved. .

  In the non-pneumatic tire according to the present invention, the inner peripheral surface of the outer annular portion is formed such that the protruding height of the central portion with respect to the both side portions is 5 to 20% of the tire width. Is preferred. If the projecting height of the central portion is within this range, while reducing the stress concentration at the connecting portion, the tire radial direction length of the connecting portion is shortened and the ride comfort is deteriorated and the weight of the outer annular portion is increased. Deterioration of fuel consumption performance due to can be suppressed.

Front view showing an example of the non-pneumatic tire of the present invention Tire meridian cross-sectional view showing an example of the non-pneumatic tire of the present invention Tire meridian cross-sectional view showing a non-pneumatic tire according to another embodiment Tire meridian cross-sectional view showing a non-pneumatic tire according to another embodiment Schematic diagram for explaining the evaluation test method Tire meridian cross-sectional view showing a non-pneumatic tire of Comparative Example 1 Tire meridian cross-sectional view showing non-pneumatic tires of Comparative Examples 2 to 6 Tire meridian cross-sectional view showing non-pneumatic tires of Examples 1 to 5

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing an example of a non-pneumatic tire of the present invention. 2 is a tire meridian cross-sectional view showing an example of the non-pneumatic tire of the present invention, and is a cross-sectional view taken along the line II of FIG. Here, O indicates the shaft core, W indicates the tire width, and H indicates the tire cross-sectional height.

  The non-pneumatic tire T of the present invention is preferably used in a vehicle that is cornered with a camber. The non-pneumatic tire T according to the present embodiment includes an inner annular portion 1, an intermediate annular portion 2 provided concentrically on the outer side thereof, and a concentric outer shape provided on the outer side thereof, from the central portion in the tire width direction to both side portions. An outer annular portion 3 having a tread surface 6 having a curvature such that the outer diameter gradually decreases, a plurality of inner coupling portions 4 that couple the inner annular portion 1 and the intermediate annular portion 2, and the outer annular portion 3. And a plurality of outer connecting portions 5 that connect the intermediate annular portion 2 to each other. Although the non-pneumatic tire T of the present embodiment includes the intermediate annular portion 2, the intermediate annular portion 2 is not always necessary, the intermediate annular portion 2 is not provided, and the inner connecting portion 4 and the outer connecting portion 5 are continuous. One connecting portion may be configured. In this case, the non-pneumatic tire T is provided concentrically on the inner annular portion 1 and on the outer side of the inner annular portion 1, and the outer diameter gradually decreases from the center portion in the tire width direction toward both side portions. It becomes the structure provided with the outer side annular part 3 provided with the tread surface 6 which has a certain curvature, and the some connection part which connects the inner side annular part 1 and the outer side annular part 3. As shown in FIG.

  The inner annular portion 1 is preferably a cylindrical shape having a constant thickness from the viewpoint of improving uniformity. Moreover, it is preferable to provide the inner peripheral surface of the inner annular portion 1 with irregularities or the like for maintaining fitting properties for mounting with an axle or a rim.

  The thickness of the inner annular portion 1 is preferably 6 to 30%, and 10 to 20% of the tire cross-section height H from the viewpoint of reducing weight and improving durability while sufficiently transmitting force to the inner connecting portion 4. More preferred.

  An inner diameter of the inner annular portion 1 is appropriately determined in accordance with a rim on which the non-pneumatic tire T is mounted, a size of an axle, and the like. However, in the present embodiment, the inner annular portion 1 is provided with an inner diameter of the inner annular portion 1. It is possible to make it smaller. The inner annular portion 1 has an inner diameter of preferably 50 to 560 mm, and more preferably 80 to 200 mm.

  The width in the tire width direction of the inner annular portion 1 is appropriately determined according to the use, the length of the axle, and the like, but is preferably 30 to 100 mm, and more preferably 40 to 80 mm.

  The tensile modulus of the inner annular portion 1 is preferably from 1 to 180000 MPa, more preferably from 1 to 50000 MPa, from the viewpoint of reducing weight, improving durability, and wearing properties while sufficiently transmitting force to the inner connecting portion 4. In addition, the tensile modulus in this invention is a value of the tensile stress at the time of 10% elongation when a tensile test is performed according to JIS K7312.

  The intermediate annular portion 2 is preferably a cylindrical shape with a constant thickness from the viewpoint of improving uniformity, but may be a polygonal cylindrical shape or the like.

  The thickness of the intermediate annular portion 2 is preferably 3 to 10% of the tire cross-section height H from the viewpoint of reducing the weight and improving the durability while sufficiently reinforcing the inner connecting portion 4 and the outer connecting portion 5. -9% is more preferable.

  The inner annular portion 2 has an inner diameter that exceeds the inner diameter of the inner annular portion 1 and less than the inner diameter of the outer annular portion 3. However, the inner ring portion 2 has an inner diameter of 20 to a value obtained by subtracting the inner ring portion 1 from the inner ring portion 3 from the viewpoint of improving the reinforcing effect of the inner connecting portion 4 and the outer connecting portion 5. The value of 80% is preferably the inner diameter added to the inner diameter of the inner annular portion 1, and the value of 30 to 60% is more preferably the inner diameter added to the inner diameter of the inner annular portion 1.

  The width in the tire width direction of the intermediate annular portion 2 is appropriately determined according to the use and the like, but is preferably 30 to 100 mm, and more preferably 40 to 80 mm.

  The tensile modulus of the intermediate annular portion 2 is preferably 1 to 180000 MPa, and more preferably 1 to 50000 MPa.

  The outer annular portion 3 has a cylindrical shape whose thickness changes in the tire width direction. The outer peripheral surface of the outer annular portion 3 is a tread surface 6. As shown in FIG. 2, the tread surface 6 has an arc shape having a curvature such that the outer diameter gradually decreases from the center in the tire width direction toward both sides in the tire meridian cross section. Since the tread surface 6 has a curvature, the ground contact area does not become too small even when cornering with a camber, and the variation of the ground contact area between straight traveling and cornering is reduced. The radius of curvature R of the tread surface 6 is preferably 40 to 100 mm, and more preferably 40 to 65 mm. When the curvature radius R is smaller than 40 mm, the ground contact area at the time of camber becomes excessive, and the grip performance increases rapidly, resulting in a situation close to a sudden stop. Moreover, when the curvature radius R is larger than 100 mm, the ground contact area at the time of camber becomes too small, and the grip performance is drastically lowered, so that slip occurs. The tread surface 6 can be provided with the same pattern as a conventional pneumatic tire as a tread pattern.

  In the tire meridian cross section, the inner peripheral surface 7 of the outer annular portion 3 is formed in an arcuate convex shape in which a central portion 7a in the tire width direction protrudes inward in the tire radial direction from both side portions 7b. The inner peripheral surface 7 is preferably formed such that the protruding height h of the central portion 7a with respect to both side portions 7b is 5 to 20% of the tire width W, so that it becomes 5 to 10%. More preferably, it is formed. When the protrusion height h is 5% or less of the tire width W, it is difficult to obtain the effect of relaxing the stress concentration of the outer connecting portion 5. In addition, when the protruding height h is 20% or more of the tire width W, the weight of the outer annular portion 3 increases, leading to deterioration of fuel consumption performance, or the outer connecting portion 5 is shortened and is not easily deformed. It gets worse.

  Although the internal diameter of the outer side annular part 3 is suitably determined according to the use etc., for example, 100-600 mm is preferable and 120-300 mm is more preferable.

  The width of the outer annular portion 3 in the tire width direction is appropriately determined according to the application and the like, but is preferably 30 to 100 mm, and more preferably 40 to 80 mm.

  The tensile modulus of the outer annular portion 3 is preferably 1 to 180000 MPa, and more preferably 1 to 50000 MPa.

  The inner connecting portion 4 connects the inner annular portion 1 and the intermediate annular portion 2, and a plurality of inner connecting portions 4 are provided so as to be independent from each other in the tire circumferential direction, for example, by providing an appropriate interval therebetween. The inner connecting portion 4 is preferably provided regularly in the tire circumferential direction from the viewpoint of improving uniformity.

  As for the number of inner connection parts 4 provided over the entire circumference (when a plurality of inner connection parts 4 are provided in the axial direction, it is counted as one), while supporting the load from the vehicle sufficiently, weight reduction, improvement of power transmission, durability From the viewpoint of improving the quality, 20 to 60 are preferable, and 20 to 50 are more preferable. FIG. 1 shows an example in which 30 inner connecting portions 4 are provided.

  Examples of the shape of each inner connecting portion 4 include a plate-like body and a columnar body. In this embodiment, an example of a plate-like body is shown. These inner connection parts 4 are extended in the tire radial direction or the direction inclined from the tire radial direction in the front sectional view. In the present invention, from the viewpoint of improving the durability by increasing the break point and making it difficult to change the rigidity, the extending direction of the inner connecting portion 4 is preferably within ± 30 ° in the tire radial direction in the front sectional view. The tire radial direction is more preferably within ± 15 °. FIG. 1 shows an example in which the inner connecting portion 4 is extended in the tire radial direction.

  The thickness of the inner connecting portion 4 is preferably 3 to 12% of the tire cross-sectional height H from the viewpoint of reducing the weight, improving the durability, and improving the lateral rigidity while sufficiently transmitting the force from the inner annular portion 1. 4 to 10% is more preferable.

  The tensile modulus of the inner connecting portion 4 is preferably 1 to 50 MPa, more preferably 1 to 30 MPa from the viewpoint of reducing weight, improving durability, and improving lateral rigidity while sufficiently transmitting the force from the inner annular portion 1. preferable.

  The outer connecting portion 5 connects the outer annular portion 3 and the intermediate annular portion 2, and a plurality of outer connecting portions 5 are provided so that each is independent in the tire circumferential direction, for example, by providing an appropriate interval therebetween. The outer connecting portion 5 is preferably provided regularly in the tire circumferential direction from the viewpoint of improving uniformity.

  In addition, the outer side connection part 5 and the inner side connection part 4 may be provided in the same position of a perimeter, and may be provided in a different position. That is, the outer connecting portion 5 and the inner connecting portion 4 do not necessarily extend so as to be continuous in the same direction as shown in FIG.

  As for the number of outer connecting parts 5 provided over the entire circumference (when a plurality of outer connecting parts 5 are provided in the axial direction, they are counted as one), while supporting the load from the vehicle sufficiently, weight reduction, improvement of power transmission, durability From the viewpoint of improving the quality, 20 to 60 are preferable, and 20 to 50 are more preferable. FIG. 1 shows an example in which 30 outer connecting parts 5 are provided in the same manner as the inner connecting part 4. In addition, the number of the outer side connection parts 5 and the number of the inner side connection parts 4 do not necessarily need to be the same, and you may provide more outer side connection parts 5 than the inner side connection parts 4. FIG.

  Examples of the shape of each outer connecting portion 5 include a plate-like body and a columnar body. In this embodiment, an example of a plate-like body is shown. These outer connecting portions 5 extend in a tire radial direction or a direction inclined from the tire radial direction in a front sectional view. In the present invention, from the viewpoint of improving the durability by increasing the break point and making it difficult to change the rigidity, the extending direction of the outer connecting portion 5 is preferably within ± 30 ° in the tire radial direction in the front sectional view. The tire radial direction is more preferably within ± 15 °. FIG. 1 shows an example in which the outer connecting portion 5 is extended in the tire radial direction.

  The thickness of the outer connecting portion 5 is preferably 3 to 12% of the tire cross-section height H from the viewpoint of reducing weight, improving durability, and improving lateral rigidity while sufficiently transmitting the force from the inner annular portion 1. 4 to 10% is more preferable.

  The tensile modulus of the outer connecting portion 5 is preferably 1 to 50 MPa, more preferably 1 to 30 MPa from the viewpoint of reducing weight, improving durability, and improving lateral rigidity while sufficiently transmitting the force from the inner annular portion 1. preferable.

  The non-pneumatic tire T is formed of an elastic material. The elastic material in the present invention refers to a material having a tensile modulus calculated from a tensile stress at 10% elongation by a tensile test according to JIS K7312 and 100 MPa or less. The elastic material of the present invention preferably has a tensile modulus of 0.1 to 100 MPa, more preferably 0.1 to 50 MPa, from the viewpoint of imparting adequate rigidity while obtaining sufficient durability. Examples of the elastic material used as the base material include thermoplastic elastomers, crosslinked rubbers, and other resins.

  Examples of the thermoplastic elastomer include polyester elastomer, polyolefin elastomer, polyamide elastomer, polystyrene elastomer, polyvinyl chloride elastomer, polyurethane elastomer and the like. Rubber materials constituting the crosslinked rubber material include natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IIR), nitrile rubber (NBR), hydrogenated nitrile rubber (hydrogenated NBR). And synthetic rubbers such as chloroprene rubber (CR), ethylene propylene rubber (EPDM), fluorine rubber, silicon rubber, acrylic rubber, and urethane rubber. These rubber materials may be used in combination of two or more as required.

  Examples of other resins include thermoplastic resins and thermosetting resins. Examples of the thermoplastic resin include polyethylene resin, polystyrene resin, and polyvinyl chloride resin, and examples of the thermosetting resin include epoxy resin, phenol resin, polyurethane resin, silicon resin, polyimide resin, and melamine resin.

  Of the above elastic materials, a polyurethane resin is preferably used from the viewpoint of moldability / workability and cost. In addition, as an elastic material, you may use a foaming material, and what used said thermoplastic elastomer, crosslinked rubber, and other resin foamed can be used.

  The inner annular portion 1, the intermediate annular portion 2, the outer annular portion 3, the inner connecting portion 4, and the outer connecting portion 5 formed of an elastic material are preferably reinforced by reinforcing fibers.

  Examples of the reinforcing fibers include reinforcing fibers such as long fibers, short fibers, woven fabrics, and non-woven fabrics. As a form using long fibers, fibers arranged in the tire axial direction and fibers arranged in the tire circumferential direction It is preferable to use a net-like fiber assembly composed of:

  Examples of the types of reinforcing fibers include rayon cords, polyamide cords such as nylon-6,6, polyester cords such as polyethylene terephthalate, aramid cords, glass fiber cords, carbon fibers, and steel cords.

  In the present invention, in addition to reinforcement using reinforcing fibers, it is possible to perform reinforcement with a granular filler or reinforcement with a metal ring or the like. Examples of the particulate filler include ceramics such as carbon black, silica, and alumina, and other inorganic fillers.

  The non-pneumatic tire T in the present invention is formed of an elastic material. From the viewpoint of enabling integral molding when manufacturing the non-pneumatic tire T, the inner annular portion 1, the intermediate annular portion 2, the outer annular portion 3, The inner connecting portion 4 and the outer connecting portion 5 are preferably made of basically the same material except for the reinforcing structure.

<Another embodiment>
The inner peripheral surface 7 of the outer annular portion 3 only needs to be formed in a convex shape in which the central portion 7a in the tire width direction protrudes inward in the tire radial direction from both side portions 7b in the tire meridian cross section. It does not have to be the arc shape described above. For example, a triangular shape as shown in FIG. 3A or a trapezoidal shape as shown in FIG. 3B may be used. In this case, the triangular and trapezoidal corners are preferably rounded to prevent stress concentration. In addition, if there is an angular portion in the convex shape, stress concentrates, and breakage or peeling is likely to occur at the connection interface between the outer annular portion 3 and the outer coupling portion 5, so it is particularly preferable to make the convex shape an arc shape. preferable.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation item in an Example etc. measured as follows. First, the maximum stress value of the stress concentration portion generated in the connecting portion in a state where a longitudinal load of 500 N was applied to the non-pneumatic tire was obtained. Next, the durability of the non-pneumatic tire was evaluated based on the travel distance until the tire breakage was confirmed under the condition of 6 km / h. As shown in the schematic diagram of FIG. 4, 500N was loaded on the evaluation target tire and rotated on the drum. Table 1 shows the dimensions of the outer annular portion, the maximum stress value of the stress concentration portion, and the travel distance until the tire breaks for each non-pneumatic tire.

Comparative Example 1
A non-pneumatic tire having a maximum tire outer diameter of 156 mm, a tire width of 57 mm, and a tire cross-section height H of 33 mm was produced. The radius of curvature of the tread surface was 55 mm. The distance α in the tire radial direction from the position of the maximum outer diameter of the tread surface 6 at the center in the tire width direction to the inner peripheral surface 7 is 20% of the tire width W, and the maximum outside of the tread surface 6 at both sides in the tire width direction. The distance β from the radial position to the inner peripheral surface 7 was 20% of the tire width W. That is, as shown in FIG. 5, the inner peripheral surface 7 of the outer annular portion 3 was formed so that the inner diameter was constant in the tire width direction.

Comparative Examples 2-6
As shown in FIG. 6, Comparative Example 2 is the same as Comparative Example 1 except that the distance α and the distance β are increased by the same distance. α / W and β / W were 25% in Comparative Example 2, 27.5% in Comparative Example 3, 30% in Comparative Example 4, 35% in Comparative Example 5, and 37.5% in Comparative Example 6. Thereby, the tire radial direction length of the outer connection part 5 of Comparative Examples 2 to 6 is uniformly shorter than the Comparative Example 1 in the tire width direction.

Examples 1-5
As shown in FIG. 7, the inner peripheral surface 7 of the outer annular portion 3 is compared except that the central portion 7a in the tire width direction is formed in an arcuate convex shape that protrudes inward in the tire radial direction from both side portions 7b. Examples 1 to 5 were the same as Example 1. The protrusion height h is a value obtained by subtracting the distance β from the distance α. α / W was 25% in Example 1, 27.5% in Example 2, 30% in Example 3, 35% in Example 4, and 37.5% in Example 5. As a result, h / W is 5% in Example 1, 7.5% in Example 2, 10% in Example 3, 15% in Example 4, and 17.5% in Example 5.

  As shown in Table 1, in Examples 1 to 5, compared to Comparative Example 1, the maximum stress value of the stress concentration portion of the connecting portion is reduced, and the running distance until the tire is damaged is increased and the durability is improved. I understand that I can do it. In Comparative Examples 2 to 6, the maximum stress value of the stress concentration portion is reduced and the durability is improved as compared with Comparative Example 1, but the length of the outer connecting portion in the tire radial direction is constant in the tire width direction. Compared to Examples 1 to 5, the effect of alleviating stress concentration at the center in the tire width direction of the outer connecting portion is small. Furthermore, since the weight increase of an outer side annular part becomes large in Comparative Examples 2-6, there exists a possibility that a fuel consumption performance may deteriorate compared with Examples 1-5.

DESCRIPTION OF SYMBOLS 1 Inner annular part 2 Middle annular part 3 Outer annular part 4 Inner coupling part 5 Outer coupling part 6 Tread surface 7 Inner peripheral surface of outer annular part 7a Center part in tire width direction 7b Both side parts in tire width direction T Non-pneumatic tire h Projection height

Claims (3)

An outer annular portion provided with an inner annular portion and a tread surface provided concentrically outside the inner annular portion and having a curvature such that the outer diameter gradually decreases from the central portion in the tire width direction toward both side portions. And a non-pneumatic tire comprising a plurality of connecting portions that connect the inner annular portion and the outer annular portion,
In the tire meridian cross section, the inner peripheral surface of the outer annular portion is formed in a convex shape in which a center portion in the tire width direction protrudes inward in the tire radial direction from both side portions.   The non-pneumatic tire according to claim 1, wherein an inner peripheral surface of the outer annular portion is formed in an arcuate convex shape. The inner peripheral surface of the outer annular portion is formed such that the protruding height of the central portion with respect to the both side portions is 5 to 20% of the tire width. Non-pneumatic tire described in.