JP2010274776A - Non-pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-pneumatic tire having the same performance characteristics as a pneumatic tire and producing a reduced impact noise at spoke position. <P>SOLUTION: The non-pneumatic tire includes a supporting structure SS which supports the load of vehicle. The supporting structure SS includes: an inside annular portion; an outside annular portion coaxially provided outside the inside annular portion; and a plurality of connecting portions connecting the inside annular portion and the outside annular portion. The outside of the outside annular portion is provided with a tread layer 7. A sipe 8 is provided at a projected portion on the outer surface of the tread layer 7 where a joint portion 5a between the connection portion and the outside annular portion is projected in the tire radial direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a non-pneumatic tire provided with a support structure that supports a load from a vehicle as a tire structural member, and preferably a non-pneumatic tire that can be used as a substitute for a pneumatic tire. It relates to tires.

  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. Further, 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 web spokes that transmit load forces by tension with a wheel or hub.

Special Table 2005-500932 Publication

  However, in the non-pneumatic tire of Patent Document 1, a hitting sound is generated when the position of the lower end of the web spoke contacts the ground, and noise with a frequency corresponding to the pitch of the web spoke becomes a problem. In addition to the hitting sound of the web spoke, the hitting sound of the tread can also cause noise. However, Patent Document 1 does not particularly disclose the relationship between the web spoke and the tread provided outside the annular band. .

  Accordingly, an object of the present invention is to provide a non-pneumatic tire that has the same operating characteristics as a pneumatic tire and has reduced impact noise at the spoke position.

The above object can be achieved by the present invention as described below.
That is, the non-pneumatic tire of the present invention is a non-pneumatic tire including a support structure that supports a load from a vehicle, and the support structure is concentrically formed on an inner annular portion and an outer side of the inner annular portion. An outer annular portion provided, and a plurality of connecting portions that connect the inner annular portion and the outer annular portion, and a tread layer is provided outside the outer annular portion, and an outer surface of the tread layer is provided on the outer surface of the tread layer. And the thin groove is provided in the projection part which projected the connection part of the said connection part and the said outer side annular part to the tire radial direction, It is characterized by the above-mentioned.

  In the non-pneumatic tire of the present invention, a tread layer is provided on the outer side of the outer annular portion, and the outer surface of the tread layer is a projection portion that projects a joint portion between the connecting portion and the outer annular portion in the tire radial direction. A narrow groove is provided. According to this configuration, even when the position of the lower end of the connecting portion is grounded, the rigidity is low because the narrow groove is provided on the outer surface of the tread layer to be grounded. As a result, the position of the connecting portion is reduced. The hitting sound can be reduced.

  In the above, the support structure includes the inner annular portion, an intermediate annular portion provided concentrically outside the inner annular portion, and the outer annular portion provided concentrically outside the intermediate annular portion. And a plurality of inner connecting portions that connect the inner annular portion and the intermediate annular portion, and a plurality of outer connecting portions that connect the outer annular portion and the intermediate annular portion.

  According to such a support structure, since the intermediate annular portion is interposed in the plurality of connecting portions that connect the inner annular portion and the outer annular portion, the rigidity variation due to the positional relationship between the spoke position and the center position of the ground plane is reduced. It can be made difficult to occur (see FIGS. 1A to 1D). That is, in a conventional non-pneumatic tire without an intermediate annular portion, when a longitudinal load is applied, as shown in FIG. 6A, the position of the lower end of the web spoke S1 is located at the center TC of the contact surface. The web spoke S1 hardly generates a bending force, and the web spoke S1 hardly buckles. On the other hand, as shown in FIG. 6B, the center position of the web spoke S3 is set to the ground contact surface center TC. When positioned, bending force is generated in the web spoke S3 due to deformation of the tread surface or displacement in the load direction, and buckling (bending deformation in the direction of the outer arrow) is likely to occur. As a result, when a longitudinal load is applied so as to have the same deflection amount, the reaction force from the tire is larger in the positional relationship shown in FIG. 6A than in the positional relationship shown in FIG. (Hard), and stiffness variation occurs in the ground contact state of both.

  On the other hand, in the non-pneumatic tire in which the intermediate annular portion 2 is interposed, when a longitudinal load is applied, the position of the lower end of the outer connecting portion 5 is positioned at the ground contact surface center TC as shown in FIG. 1 (a), the outer connecting portion 5 and the inner connecting portion 4 are unlikely to buckle, and as shown in FIG. 1 (d), the center position of the outer connecting portion 5 is the ground plane. Even in the case of being located at the center TC, the intermediate annular portion 2 is reinforced by tension (tension of an inward arrow on the inside) and reinforcement by compression (outer side of the outer coupling portion 5 and the inner coupling portion 4). (Compression force of an inward arrow) makes it difficult for the outer connecting portion 5 and the inner connecting portion 4 to buckle. As a result, the non-pneumatic tire of the present invention is less likely to buckle in the ground contact state compared to the prior art, and the amount of deflection and longitudinal load until buckling occurs (that is, buckling is reduced). A break point that starts to occur becomes high), and a region in which the rigidity variation is small can be set widely between the positional relationship shown in FIG. 1C and the positional relationship shown in FIG.

  FIG. 2A to FIG. 2B show the above as specific data. According to this, in the non-pneumatic tire in which the intermediate annular portion 2 is not interposed, as shown in FIG. 2 (a), the web spoke S is buckled (the state shown in FIG. 1 (b)) with a small deflection amount, and the break Whereas the point cannot be set high (a difference in rigidity occurs from the initial stage of load application), in the non-pneumatic tire in which the intermediate annular portion 2 is interposed as in the present invention, buckling occurs in the positional relationship shown in FIG. Can be made difficult to occur, so the breakpoint can be set high. In this manner, since the region where the rigidity variation is small can be set widely between the positional relationship shown in FIG. 1C and the positional relationship shown in FIG. It is possible to provide a non-pneumatic tire that hardly changes in rigidity depending on the positional relationship with the position.

  In the above, it is preferable that the depth of the narrow groove is 1/3 or more of the thickness of the tread layer, and the width of the narrow groove does not exceed the width of the projection unit. If the depth of the narrow groove is smaller than 1/3 of the thickness of the tread layer, the effect of reducing the rigidity tends to be small. In addition, when the width of the narrow groove exceeds the width of the projection portion, that is, the width of the coupling portion between the outer connecting portion and the outer annular portion, the air in the narrow groove is compressed when grounding at the position of the coupling portion, A pumping sound is generated as a result of being emitted, which causes noise. Moreover, if the width of the narrow groove is too large, the durability of the tire will also be reduced.

In the above, on the outer surface of the tread layer, a plurality of pitches having a pitch length ratio with respect to the basic pitch length of the tread pattern is within ± 10% are arranged in a variable pitch in the tire circumferential direction, and one round of the tire The total number n of the connecting portions and the total number N of the pitches preferably satisfy the following formulas (1) to (3).
1.25n ≦ N ≦ 1.325n (1)
0.625n ≦ N ≦ 0.6625n (2)
0.3125n ≦ N ≦ 0.33125n (3)

  In the non-pneumatic tire of the present invention, a plurality of pitches are arranged in a variable pitch array in the tire circumferential direction on the outer surface of the tread layer. In the present invention, one land portion and one lateral groove arranged in the tire circumferential direction of the tread pattern are collectively referred to as one pitch. Here, the basic pitch length is obtained by dividing the outer peripheral length of the tire by the total number N of pitches, and all pitches of the present invention have a pitch length ratio with respect to the basic pitch length within ± 10%. . By arranging a plurality of pitches having such a pitch length as a variable pitch in the tire circumferential direction, it is possible to disperse the frequency of pattern noise during tire running and reduce the pitch peak level of pattern noise. Furthermore, under the tread pattern in which such pitches are arranged on the outer surface of the tread layer, when the total number n of the connecting portions and the total number N of the pitches satisfy the formulas (1) to (3), the connecting portions ( The frequency at the first, second, and 0.5th order of the noise peak due to the impact sound of the spokes does not match the frequency of the noise peak due to the impact sound of the pitch, and the noise due to the impact sound of both does not increase.

Explanatory drawing for demonstrating the effect of the non-pneumatic tire of this invention The graph for demonstrating the effect of the non-pneumatic tire of this invention The front view and side view which show an example of the non-pneumatic tire of this invention Front view of the tread layer viewed from the outer periphery The figure which shows the variable pitch arrangement | sequence of Example 2. Explanatory drawing for demonstrating the subject of the conventional non-pneumatic tire

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a front view showing an example of the non-pneumatic tire of the present invention, where (a) is a front view showing the whole, and (b) is a front view showing the main part. Here, O indicates the axial center, and H1 indicates the tire cross-sectional height.

  The non-pneumatic tire T of the present invention includes a support structure SS that supports a load from a vehicle. The non-pneumatic tire T of the present invention only needs to be provided with such a support structure SS, and a member corresponding to a tread on the outer side (outer peripheral side) or inner side (inner peripheral side) of the support structure SS, A reinforcing layer, a member for fitting with an axle or a rim, and the like may be provided.

  As shown in FIG. 3, the non-pneumatic tire T of the present invention includes an inner annular portion 1, an outer annular portion 3 provided concentrically outside the inner annular portion 1, and an inner annular portion. A plurality of connecting portions for connecting the portion 1 and the outer annular portion 3 are provided. In the illustrated example, the connecting portion includes an inner connecting portion 4 and an outer connecting portion 5. In this embodiment, in this way, the support structure SS includes the inner annular portion 1, the intermediate annular portion 2 provided concentrically on the outer side thereof, and the outer annular portion 3 provided concentrically on the outer side thereof. An example in which a plurality of inner connecting portions 4 that connect the inner annular portion 1 and the intermediate annular portion 2 and a plurality of outer connecting portions 5 that connect the outer annular portion 3 and the intermediate annular portion 2 is shown.

  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 2 to 7%, and 3 to 6% of the tire cross-section height H1 from the viewpoint of reducing weight and improving durability while sufficiently transmitting force to the inner connecting portion 4. More preferred.

  The inner annular portion 1 has an inner diameter that is appropriately determined in accordance with the dimensions of the rim on which the non-pneumatic tire T is mounted, the axle, and the like. It can be made much smaller. However, when an alternative to a general pneumatic tire is assumed, 250 to 500 mm is preferable, and 330 to 440 mm is more preferable.

  The axial width of the inner annular portion 1 is appropriately determined according to the application, the length of the axle, and the like, but when an alternative to a general pneumatic tire is assumed, it is preferably 100 to 300 mm, more preferably 130 to 250 mm. preferable.

  The tensile modulus of the inner annular portion 1 is preferably 5 to 180000 MPa, more preferably 7 to 50000 MPa, from the viewpoint of reducing weight, improving durability, and wearing properties while sufficiently transmitting force to the inner connecting portion 4. The tensile modulus in the present invention is a value calculated from a tensile stress at 10% elongation by conducting a tensile test according to JIS K7312.

  As the material of the inner annular portion 1, thermoplastic elastomer, crosslinked rubber, other resins, fiber reinforcing materials obtained by reinforcing these with reinforcing materials such as fibers, metals, and the like can be used. However, from the viewpoint of enabling integral molding when manufacturing the support structure SS, the material of the inner annular portion 1 may be thermoplastic elastomer, crosslinked rubber, other resin, or fiber reinforced with fibers or the like. Reinforcing materials are preferred.

  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. A foamed material may be used, and the above-mentioned thermoplastic elastomer, crosslinked rubber, or other resin foamed can be used.

  Examples of the reinforcing material include reinforcing fibers such as long fibers, short fibers, woven fabrics, and non-woven fabrics, and granular fillers. It is preferable to use reinforcing fibers such as long fibers, short fibers, woven fabrics, and non-woven fabrics. Or, a woven fabric (including a suede-like woven fabric and a mesh-like woven fabric) using long fibers is more preferable. Examples of the 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, steel cords, and the like. Examples of the particulate filler include ceramics such as carbon black, silica, and alumina, and other inorganic fillers.

  The shape of the intermediate annular portion 2 is not limited to a cylindrical shape, and may be a polygonal cylindrical shape.

  The thickness of the intermediate annular portion 2 is preferably 3 to 10% of the tire cross-section height H1 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, as the inner diameter of the intermediate annular portion 2, the inner diameter of the inner annular portion 1 is subtracted from the inner diameter of the outer annular portion 3 from the viewpoint of improving the reinforcing effect of the inner connecting portion 4 and the outer connecting portion 5 as described above. A value of 20 to 80% of the value is preferably the inner diameter added to the inner diameter of the inner annular portion 1, and a value of 30 to 60% is more preferably the inner diameter added to the inner diameter of the inner annular portion 1. .

  The axial width of the intermediate annular portion 2 is appropriately determined according to the application and the like, but is preferably 100 to 300 mm, more preferably 130 to 250 mm, assuming an alternative to a general pneumatic tire.

  The tensile modulus of the intermediate annular portion 2 is preferably 8000 to 18000 MPa, more preferably 10,000 to 50000 MPa from the viewpoint of sufficiently reinforcing the inner connecting portion 4 and the outer connecting portion 5 to improve durability and load capacity. preferable.

  As the material of the intermediate annular portion 2, the same material as that of the inner annular portion 1 can be used, such as a thermoplastic elastomer, a crosslinked rubber, other resins, or a fiber reinforcing material obtained by reinforcing these with a reinforcing material such as a fiber, a metal, or the like. Can be used. However, when manufacturing the support structure SS, it is preferable to use the same material or base material as the material of the inner annular portion 1 from the viewpoint of enabling integral molding.

  In order to increase the tensile modulus of the intermediate annular portion 2, a fiber reinforced material in which a thermoplastic elastomer, a crosslinked rubber, or other resin is reinforced with fibers or the like is preferable. That is, as shown in FIG. 3B, the intermediate annular portion 2 is preferably reinforced by the reinforcing fibers 2a. The reinforcing fiber 2a can be provided as a single layer or a plurality of layers.

  Examples of the reinforcing fibers include long fibers, short fibers, woven fabrics, non-woven fabrics, and the like, but long fibers or woven fabrics using long fibers (including suede-like woven fabrics) are more preferable. As the reinforcing fiber at that time, for example, rayon cord, polyamide cord such as nylon-6, 6, polyester cord such as polyethylene terephthalate, aramid cord, glass fiber cord, carbon fiber, steel cord and the like are preferable.

  The shape of the outer annular portion 3 is preferably a cylindrical shape with a constant thickness from the viewpoint of improving uniformity. The thickness of the outer annular portion 3 is preferably 2 to 7% of the tire cross-section height H1, and preferably 2 to 5% from the viewpoint of reducing the weight and improving the durability while sufficiently transmitting the force from the outer connecting portion 5. Is more preferable.

  The inner diameter of the outer annular portion 3 is appropriately determined according to its use and the like, but since the intermediate annular portion 2 is provided in the present invention, the inner diameter of the outer annular portion 3 can be made larger than before. However, when an alternative to a general pneumatic tire is assumed, 420 to 750 mm is preferable, and 480 to 680 mm is more preferable.

  The axial width of the outer annular portion 3 is appropriately determined according to the application and the like, but is preferably 100 to 300 mm, and more preferably 130 to 250 mm when an alternative to a general pneumatic tire is assumed.

  The tensile modulus of the outer annular portion 3 can be set to the same level as that of the inner annular portion 1 when the reinforcing layer 6 is provided on the outer periphery of the outer annular portion 3 as shown in FIG. In the case where such a reinforcing layer 6 is not provided, 5 to 180000 MPa is preferable, and 7 to 50000 MPa is more preferable from the viewpoint of reducing the weight and improving the durability while sufficiently transmitting the force from the outer connecting portion 5. .

  As the material of the outer annular portion 3, the same material as the inner annular portion 1 can be used, such as a thermoplastic elastomer, a crosslinked rubber, other resins, or a fiber reinforcing material obtained by reinforcing these with a reinforcing material such as a fiber, a metal, or the like. Can be used. However, when manufacturing the support structure SS, it is preferable to use the same material or base material as the material of the inner annular portion 1 from the viewpoint of enabling integral molding.

  When the tensile modulus of the outer annular portion 3 is increased without providing the reinforcing layer 6, a fiber reinforced material in which a thermoplastic elastomer, a crosslinked rubber, or other resin is reinforced with fibers or the like is preferable. That is, when the reinforcing layer 6 is not provided, the outer annular portion 3 is preferably reinforced with reinforcing fibers.

  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 that each is independent in the circumferential direction, for example, by providing an appropriate interval therebetween. The inner connecting parts 4 are preferably provided with a certain interval 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, 10 to 80 are preferable, and 40 to 60 are more preferable. FIG. 3 shows an example in which 40 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 ± 25 ° in the tire radial direction in the front sectional view. The tire radial direction is more preferably within ± 15 °.

  The thickness of the inner connecting portion 4 is preferably 4 to 12% of the tire cross-sectional height H1 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. 6 to 10% is more preferable.

  In the case where a single inner connecting portion 4 is provided in the axial direction, the axial width of the inner connecting portion 4 is appropriately determined according to the application and the like, but when an alternative to a general pneumatic tire is assumed, 100 to 300 mm is Preferably, 130 to 250 mm is more preferable.

  The tensile modulus of the inner connecting portion 4 is preferably 5 to 50 MPa, more preferably 7 to 20 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.

  As the material of the inner connecting portion 4, the same material as that of the inner annular portion 1 can be used, such as a thermoplastic elastomer, a crosslinked rubber, other resins, or a fiber reinforcing material obtained by reinforcing these with a reinforcing material such as a fiber, a metal, or the like. Can be used. However, when manufacturing the support structure SS, it is preferable to use the same material or base material as the material of the inner annular portion 1 from the viewpoint of enabling integral molding.

  When the tensile modulus of the inner connecting portion 4 is increased, a fiber reinforced material in which a thermoplastic elastomer, a crosslinked rubber, or other resin is reinforced with fibers or the like is 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 of them is independent in the circumferential direction, for example, by providing an appropriate interval therebetween. The outer connecting portions 5 are preferably provided at regular intervals from the viewpoint of improving uniformity.

  The outer connecting portion 5 and the inner connecting portion 4 may be provided at the same position on the entire circumference or at different positions. However, from the viewpoint of improving the reinforcing effect of the intermediate annular portion 2, the outer connecting portion 5 and the inner connecting portion 4 are provided. The connecting portion 4 is preferably provided at the same position on the entire circumference.

  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, 10 to 80 are preferable, and 40 to 60 are more preferable. FIG. 3 shows an example in which 40 outer connecting portions 5 are provided in the same manner as the inner connecting portions 4.

  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 ± 25 ° in the tire radial direction in the front sectional view. The tire radial direction is more preferably within ± 15 °.

  The thickness of the outer connecting portion 5 is preferably 4 to 12% of the tire cross-sectional height H1 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. 6 to 10% is more preferable.

  In the case where a single outer connecting portion 5 is provided in the axial direction, the axial width of the outer connecting portion 5 is appropriately determined according to the application and the like, but assuming an alternative to a general pneumatic tire, 100 to 300 mm is Preferably, 130 to 250 mm is more preferable.

  The tensile modulus of the outer connecting portion 5 is preferably 5 to 50 MPa, more preferably 7 to 20 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.

  As the material of the outer connecting portion 5, the same material as that of the inner annular portion 1 can be used, such as a thermoplastic elastomer, a crosslinked rubber, other resins, or a fiber reinforcing material obtained by reinforcing these with a reinforcing material such as a fiber, a metal, or the like. Can be used. However, when manufacturing the support structure SS, it is preferable to use the same material or base material as the material of the inner annular portion 1 from the viewpoint of enabling integral molding.

  When the tensile modulus of the outer connecting portion 5 is increased, a fiber reinforced material in which a thermoplastic elastomer, a crosslinked rubber, or other resin is reinforced with fibers or the like is preferable.

  In the present embodiment, as shown in FIG. 3, an example is shown in which a reinforcing layer 6 that reinforces bending deformation of the outer annular portion 3 is provided outside the outer annular portion 3 of the support structure SS. The reinforcing layer 6 can be the same as the belt layer of a conventional pneumatic tire.

  The reinforcing layer 6 is composed of one or a plurality of layers. For example, a steel cord, an aramid cord, a rayon cord, etc. rubberized layers arranged in parallel at an inclination angle of about 20 ° with respect to the tire circumferential direction are used as a steel cord. Etc. can be formed so as to cross in the opposite direction. In this embodiment, the reinforcement layer 6 shows the example comprised from 3 layers 6a, 6b, 6c. Further, a layer made of various cords arranged in parallel in the tire circumferential direction may be provided on the upper layer of both layers.

  In the present embodiment, as shown in FIG. 3, a tread layer 7 is provided on the outer side of the reinforcing layer 6. As the tread layer 7, it is possible to provide the same tread layer as that of a conventional pneumatic tire.

  For example, the raw material of the tread rubber forming the tread layer 7 includes natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR) and the like. These rubbers are reinforced with fillers such as carbon black and silica, and a vulcanizing agent, a vulcanization accelerator, a plasticizer, an antiaging agent, and the like are appropriately blended.

  A front view of the tread layer 7 viewed from the outer peripheral side is shown in FIG. The arrow A direction indicates the tire circumferential direction, the arrow B direction indicates the tire width direction, and the direction perpendicular to the paper surface indicates the tire radial direction. In the drawing, a portion indicated by a broken line in the tire width direction B indicates a coupling portion 5 a between the outer annular portion 3 and the outer coupling portion 5 on the inner peripheral side of the outer annular portion 3. On the outer surface of the tread layer 7, a projected portion obtained by projecting the coupling portion 5 a in the tire radial direction, that is, on the opposite side of the coupling portion 5 a across the tread layer 7, a sipe (thin groove) as shown in the figure. 8) is formed. The sipe 8 may be formed linearly in the entire region in the tire width direction B, or may be formed in a broken line shape as shown in FIG. Moreover, the depth of the sipe 8 is 1/3 or more of the thickness of the tread layer 7, and it is preferable that the width of the sipe 8 does not exceed the width of the projection part (joining part 5a). Specifically, the width of the sipe 8 is preferably 0.5 to 2.0 mm, and more preferably 1.0 to 1.5 mm.

  The tread pattern is composed of a plurality of grooves (lateral grooves) 10 formed in the tire circumferential direction A and land portions 11 divided by the grooves 10. The pitch 9 includes a pair of land portions 11 and groove portions 10. In the present embodiment, on the outer surface of the tread layer 7, a so-called variable pitch arranged tread pattern in which a plurality of pitches 9 having different pitch lengths are arranged in the tire circumferential direction A is formed. FIG. 4 shows an example in which three types of pitches 9a, 9b, and 9c are arranged in the tire circumferential direction A, and the pitch lengths are Pa, Pb, and Pc, respectively. In addition, the pitch length of the pitch 9 was made into the distance of the center positions of the groove part 10 adjacent to the tire circumferential direction A as shown in the figure for convenience.

  In the example shown in FIG. 4, three types of pitches 9a, 9b, and 9c are arranged on the left side of the figure, and four types of pitches 9a ′, 9b ′, 9c ′, and 9d ′ are arranged on the right side. The rows of pitches 9 adjacent to each other in the tire width direction B may be different as described above or the same. Further, the pitches 9 arranged in the tire circumferential direction A may be three types, four types, or five or more types as shown in the figure.

  Further, when the rows of pitches 9 adjacent to each other in the tire width direction B are the same, they may be arranged at the same position in the tire circumferential direction A or may be arranged shifted from each other in the tire circumferential direction A. Furthermore, three or more rows of pitch 9 may be provided in the tire width direction B.

  As a variable pitch arrangement of the tread pattern, a method of randomly arranging a plurality of pitches 9 having different pitch lengths in the tire circumferential direction A is used. Generally, by arranging the variable pitch, it is possible to disperse the frequency of the pattern noise during tire running and reduce the pitch peak level of the pattern noise.

  By the way, in this invention, when arranging the several pitch 9, it is necessary to consider the impact sound to the road surface by the outer side connection part 5 (spoke). That is, since the frequency noise determined by the number of tire pitches and the number of revolutions appears remarkably in the pattern noise, it is necessary that the noise peak due to this pitch does not match the noise peak due to the impact sound of the spokes.

  Below, an example at the time of arranging the several pitch 9 in variable pitch is shown. In the present embodiment, an example in which three types of pitches 9a, 9b, and 9c are used as the plurality of pitches 9 having different pitch lengths. Here, assuming that the pitch lengths of the pitch 9a, the pitch 9b, and the pitch 9c are Pa, Pb, and Pc, respectively, Pa is 90 to 100% of Pb, and Pc is 100 to 110% of Pb. That is, in this embodiment, the pitch length Pb of the pitch 9b is the basic pitch length.

  The tread pattern is configured by arranging a plurality of pitches 9a, 9b, 9c in the tire circumferential direction A. The total number of pitches 9a, 9b, 9c arranged in the tread pattern is determined as follows. Is done.

First, assuming that the frequency of the impact sound on the road surface by the outer connecting portion 5 (spoke) is Fs,
Fs = V / L × n
It can be expressed as. Here, V is the speed (m / s), L is the tire circumference (m), and n is the total number of tires of the outer connecting portion 5 for one circumference.

Moreover, when the frequency of the hitting sound on the road surface with the pitches 9a, 9b, and 9c is Fp,
Fp = V / L × N
It can be expressed as. Here, V is the speed (m / s), L is the tire circumference (m), and N is the total number of tires of one pitch 9a, 9b, 9c.

  Next, the noise peak due to the impact sound of the spoke 5 and the noise peak due to the impact sound of the pitch 9a, 9b, 9c are not matched, that is, the primary, secondary, tertiary, 0.5th order, etc. of the spoke 5 And the frequency Fp of the pitches 9a, 9b, and 9c are set so as not to coincide with each other.

Here, the relationship between n and N is, for example,
1.25n ≦ N ≦ 1.325n (1)
0.625n ≦ N ≦ 0.6625n (2)
0.3125n ≦ N ≦ 0.33125n (3)
If the total number of pitches 9a, 9b, and 9c is set so as to satisfy the condition, none of the frequencies of the pitches 9a, 9b, and 9c matches the frequency Fs of the spoke 5. In the present embodiment, the total number N of the plurality of pitches 9a, 9b, 9c is determined as described above. Based on this total number N, a plurality of pitches 9a having a pitch length of Pa, pitches 9b having a pitch length of Pb, and pitches 9c having a pitch length of Pc are arranged, and the total pitch length matches the tire circumferential length L. Like that. As long as the total pitch length matches the tire circumferential length L, the arrangement order of the pitches 9a, 9b, and 9c is not limited.

  The non-pneumatic tire T of the present invention can be manufactured by forming the support structure SS by molding, injection molding, or the like, and then forming the reinforcing layer 6, the tread layer 7 or the like as necessary. When reinforcing fibers are used as the reinforcing structure of the support structure SS, the fiber reinforcing structure can be formed by arranging the reinforcing fibers in the mold in advance.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below.

Example 1 (with sipes)
Inner ring part (inner ring) 1, intermediate ring part (intermediate ring) 2, outer ring part (outer ring) 3, inner connection part (inner spoke) 4, outer connection part in the dimensions and physical properties shown in Table 1 A non-pneumatic tire T including a support structure SS including (outside spokes) 5, three reinforcing layers 6 provided on the outer periphery thereof, and a tread layer 7 was produced, and noise evaluation was performed. The outer diameters of the non-pneumatic tires T of Example 1 and the following examples and comparative examples were all 540 mm.

  The non-pneumatic tire T of Example 1 is shown in Table 2 on a projection portion which is an outer surface of the tread layer 7 and is a projection portion in which a joint portion 5a between the outer connecting portion 5 and the outer annular portion 3 is projected in the tire radial direction. A sipe 8 is provided in size. Also, the pitch lengths are all equal. The results of noise evaluation are shown in Table 2.

  In addition, noise evaluation was evaluated by stand-alone tire noise. The stand-alone tire noise was tested according to JASO-C606. The speed was 40 km / h, a longitudinal load of 2500 N was applied, and the pitch peak level (dB) at this time was evaluated.

Comparative Example 1 (no sipes)
A non-pneumatic tire T including the support structure SS, the three reinforcing layers 6 provided on the outer periphery of the support structure SS, and the tread layer 7 with the same dimensions and physical properties as in Example 1 of Table 1 is manufactured, and noise evaluation is performed. Was done. However, unlike the first embodiment, the non-pneumatic tire T of the first comparative example is not provided with the sipe 8. The results of noise evaluation are shown in Table 2.

Comparative Example 2 (Sipe position shift)
A non-pneumatic tire T including the support structure SS, the three reinforcing layers 6 provided on the outer periphery of the support structure SS, and the tread layer 7 with the same dimensions and physical properties as in Example 1 of Table 1 is manufactured, and noise evaluation is performed. Was done. However, in the non-pneumatic tire T of the comparative example 2, the position of the sipe 8 is changed from that of the first embodiment, and the sipe 8 is provided off the projection unit. The results of noise evaluation are shown in Table 2.

Comparative example 3 (wide sipe)
A non-pneumatic tire T including the support structure SS, the three reinforcing layers 6 provided on the outer periphery of the support structure SS, and the tread layer 7 with the same dimensions and physical properties as in Example 1 of Table 1 is manufactured, and noise evaluation is performed. Was done. However, in the non-pneumatic tire T of Comparative Example 3, the width of the sipe 8 is changed from that of Example 1 and is 2.5 mm. The results of noise evaluation are shown in Table 2.

Example 2 (with sipe and variable pitch)
A non-pneumatic tire T including the support structure SS, the three reinforcing layers 6 provided on the outer periphery thereof, and the tread layer 7 with the same dimensions and physical properties as those of Example 1 in Table 1 is manufactured, and noise evaluation is performed. Was done. In the non-pneumatic tire T of the second embodiment, the tread pattern is formed in a variable pitch arrangement with respect to the non-pneumatic tire T of the first embodiment. As the variable pitch arrangement, the pitch lengths Pa, Pb and Pc of the above-mentioned three types of pitches 9a, 9b and 9c are 29.475 mm, 32.750 mm and 36.025 mm, respectively, and the tire circumferential direction of the pitch 9a, 9b and 9c The arrangement of was as shown in FIG. The results of noise evaluation are shown in Table 2.

Comparative Example 4 (the relationship between the total number n of spokes and the total number N of pitches is other than the formulas (1) to (3))
In the same manner as in Example 2, a non-pneumatic tire T including the support structure SS, the three reinforcing layers 6 provided on the outer periphery thereof, and the tread layer 7 was produced, and noise evaluation was performed. However, in the comparative example 4, the total number n of the outer coupling portions 5 and the total number N of the pitches 9 are different from those of the second embodiment so that none of the above formulas (1) to (3) is satisfied. . The results of noise evaluation are shown in Table 2.

  The following can be understood from the results of Tables 1 and 2. The pitch peak level in Table 2 is based on the value of Example 1. As shown in Table 2, the non-pneumatic tire of Example 1 has a reduced pitch peak level as compared with the non-pneumatic tire of Comparative Example 1. This is presumably because the sipe 8 is provided on the outer surface of the tread layer 7 to be grounded, so that the rigidity is lowered, and as a result, the impact sound at the position of the outer connecting portion 5 is reduced.

  Compared with Comparative Example 1, the non-pneumatic tire of Comparative Example 2 shows a reduction in noise due to the provision of the sipe 8, but when compared with the non-pneumatic tire of Example 1, the sipe 8 deviates from the projection unit. Therefore, it can be seen that the effect of noise reduction by sipes is small.

  Compared with the non-pneumatic tire of Example 1, the non-pneumatic tire of Comparative Example 3 shows a worsening of noise. This indicates that if the width of the sipe is too wide, a pumping sound of the outer connecting portion 5 (spoke) is generated, causing noise.

  The non-pneumatic tire of Example 2 has a reduced pitch peak level as compared with the non-pneumatic tire of Example 1. By arranging the variable pitch, it is considered that the frequency of the pattern noise at the time of running the tire is dispersed and the pitch peak level of the pattern noise is reduced.

  The non-pneumatic tire of Comparative Example 4 has a higher pitch peak level than the non-pneumatic tire of Example 2. This is because the total number n of the outer coupling parts 5 and the total number N of the pitches 9 do not satisfy any of the above formulas (1) to (3), so the frequency of the outer coupling parts 5 and the frequency of the pitch 9 match. Then, it is considered that the pitch peak level is increasing.

DESCRIPTION OF SYMBOLS 1 Inner ring part 2 Middle ring part 3 Outer ring part 4 Inner connection part 5 Outer connection part 6 Reinforcement layer 7 Tread layer 8 Sipe 9 Pitch 10 Groove part 11 Land part

Claims (4)

A non-pneumatic tire comprising a support structure for supporting a load from a vehicle,
The support structure includes an inner annular portion, an outer annular portion provided concentrically on the outer side of the inner annular portion, and a plurality of connecting portions that connect the inner annular portion and the outer annular portion,
A tread layer is provided on the outer side of the outer annular portion, and a narrow groove is provided on a projection portion that is an outer surface of the tread layer and projects a joint portion between the connecting portion and the outer annular portion in a tire radial direction. Non-pneumatic tire that has been.   The support structure includes the inner annular portion, an intermediate annular portion provided concentrically outside the inner annular portion, the outer annular portion provided concentrically outside the intermediate annular portion, 2. The non-pneumatic tire according to claim 1, further comprising: a plurality of inner connecting portions that connect the inner annular portion and the intermediate annular portion; and a plurality of outer connecting portions that connect the outer annular portion and the intermediate annular portion.   The depth of the narrow groove is 1/3 or more of the thickness of the tread layer, and the width of the narrow groove does not exceed the width of the projection unit. Non-pneumatic tire. On the outer surface of the tread layer, a plurality of pitches having a pitch length ratio with respect to the basic pitch length of the tread pattern within ± 10% are arranged in a variable pitch in the tire circumferential direction, and the tire for one round of the tire is arranged. The non-pneumatic tire according to any one of claims 1 to 3, wherein a total number n of connecting portions and a total number N of the pitches satisfy the following formulas (1) to (3).
1.25n ≦ N ≦ 1.325n (1)
0.625n ≦ N ≦ 0.6625n (2)
0.3125n ≦ N ≦ 0.33125n (3)

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