JP4819713B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can balance steering stability and ride comfort in a high dimension.

  Conventionally, in order to improve the handling stability of a pneumatic tire, the tire flatness is reduced to secure a tread contact area, a hard rubber composition is used for the bead filler, or between the side part and the shoulder part. Techniques such as improving the lateral rigidity of the tire by additionally arranging a reinforcing material and changing the tread rubber have been taken. On the other hand, in order to improve ride comfort, a technique has been adopted in which the longitudinal rigidity of the tire is reduced by improving the envelope of the tread portion by changing the angle of the belt cord or by changing the structure of the carcass or bead filler. For example, in Patent Documents 1 and 2 listed below, tires with shoulder reinforcement layers made of textile cords or steel cords, tires with reinforcement rubber layers arranged on the inside and outside of the carcass of the shoulder portion, and improved steering stability, patents Document 3 describes that a metal cord is used for the carcass to simultaneously improve steering stability and vibration ride comfort.

However, it is generally known that the above-mentioned measures for improving steering stability and riding comfort are in a trade-off relationship with each other, and that the stiffness in the three directions of the longitudinal, lateral, and longitudinal stiffness of the tire changes with a positive relationship. That is, when the longitudinal rigidity is increased, the lateral and front-rear rigidity are also increased. Therefore, it has been difficult to balance and improve both the handling stability and the ride comfort at a high level.
JP 7-179101 A JP 2001-138708 A Japanese Patent Laid-Open No. 11-11109

  In view of the above-mentioned contradiction, the object of the present invention is to provide a pneumatic tire that can balance and improve both steering stability and riding comfort at a high level.

  The present inventor conducted intensive studies to solve the above-mentioned problems, and by changing the relationship between the longitudinal stiffness and the lateral stiffness of a conventional tire and controlling each independently, the present invention is flexible in the longitudinal direction. It has been found that the above-mentioned problems can be solved by imparting to the tire the property of being rigid in the lateral direction and being independent of each other in the longitudinal and lateral directions.

  That is, the present invention includes a bead portion including a pair of bead cores, a sidewall portion extending outward in the tire radial direction from the bead portion, and a tread portion provided between the sidewall portions. In a pneumatic tire in which a carcass composed of at least one layer of carcass ply mounted between bead portions of the belt and a belt composed of at least two layers of belt ply are arranged on the outer peripheral side of the tread portion of the carcass, both end portions of the belt A laminated structural member in which a plurality of annular plate materials and rubber materials are alternately arranged and laminated is embedded in a buttress portion on the outer side in the tire radial direction of the carcass between an outer side and a tire maximum width portion. It is a pneumatic tire.

In the present invention, the plate material preferably has a longitudinal elastic modulus in a range of 10 to 25,000 kgf / mm ² .

  Further, it is effective that the arrangement angle of the plate material in the tire radial direction is in a range of 0 ± 10 ° with respect to a vertical line lowered from the tire rotation axis to the ground contact surface.

  Further, in the pneumatic tire according to the present invention, at least one carcass ply of the carcass is divided on the circumference of the tire at the position of the laminated structural member, and the carcass ply divided end portion is annular on the tire circumference. It can be sandwiched between the gaps between the plate materials.

  According to the pneumatic tire of the present invention, since the laminated structure member having a laminated structure embedded in the buttress portion has a directionality and deforms when a load is applied, the rate of increase in the tire longitudinal rigidity and lateral rigidity when the load is applied. Can be controlled independently of each other. In other words, it is flexible with respect to the longitudinal deflection of the tire (input in the tire radial direction) and rigid with respect to the lateral deflection (input in the tire axial direction). It is possible to balance and improve both ride comfort and high dimension.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a half-sectional view showing a pneumatic tire for passenger cars (hereinafter, the pneumatic tire may be simply referred to as “tire”) 1 according to an embodiment of the present invention. FIG. 2 is an enlarged partial cross-sectional view of the buttress portion 10 of the tire 1 in FIG.

  The pneumatic tire 1 is grounded on a road surface provided between a pair of bead portions 4 that are assembled into a rim, a sidewall portion 3 that extends outward in the tire radial direction from the bead portion 4, and the sidewall portions 3, 3. And the tread portion 2 that is configured. The basic structure of the tire 1 is the same as the tire 30 having the conventional general structure shown in FIG.

  As shown in FIG. 1, the tire 1 includes two pairs of carcass plies 61 and 62 made of organic fiber cords such as polyester and rayon extending at an angle of about 90 ° with respect to the tire equator line CL. The carcass 6 is folded around from the inside of the tire to the outside around the bead core 5 embedded therein and locked with the bead filler 9 interposed therebetween, and the inside of the tread portion 2 is inclined at an angle of 15 to 35 ° with respect to the equator line CL. The belt 7 is composed of at least two layers of crossed belt plies using steel cords, aramid fibers, etc., and the outer periphery of the belt 7 is spirally wound at an angle of approximately 0 ° with respect to the tire circumferential direction. It is a tire for passenger cars with a radial structure having a cap ply 8 made of an organic fiber cord such as nylon, and the tread part 2 has the required performance and use of the tire. Ribs on the tread surface depending on the matter, various tread patterns such block is formed.

  The tire 1 includes a buttress portion 10 positioned between the outer side of the tire axial ground contact region and the maximum tire width portion W that is disengaged from the belt end portions 7a on both sides of the belt 7, and a buttress portion on the outer side in the tire radial direction of the carcass 6. In FIG. 10, a laminated structural member 11 in which a plurality of annular plate members 12 are laminated is embedded.

  As shown in the front view and the side view of the plate member 12 in FIG. 3, the laminated structural member 11 includes a plate member 12 having a circular cross-section that is continuous in the circumferential direction, and a plurality of the plate members 12 and the plate member 12. It is a laminated structure in which rubber materials are alternately arranged and laminated.

  The dimensions of the plate member 12, the rubber thickness between the plate members 12, the number of laminated layers, etc. are not particularly limited, and can be appropriately determined depending on the tire size, the cross-sectional shape of the buttress portion, the rubber thickness thereof, and the like.

  For example, in the case of a passenger car tire, the thickness W of the plate member 12 is 0.1 to 2.0 mm, preferably 0.2 to 1.5 mm. If the thickness W is too thin, the plate material will be flexible and the required vertical and lateral rigidity will not be obtained, and if it is too thick, it will be difficult to ensure steering stability and ride comfort due to high rigidity in both the vertical and horizontal directions. Further, the dynamic adhesiveness is lowered due to the difference in rigidity with the adjacent rubber material. Further, the plate width H and the outer diameter D are appropriately determined depending on the tire size, required characteristics, etc. For example, the ratio of the plate thickness W to the width H is about H / W = 5 to 30, and H / W = 8 to A range of 20 is more preferred. The upper limit of the number of stacked sheets is not particularly limited, but is about 10 in the case of passenger car tires.

  As shown in FIG. 4, the plate material 12 has a plurality of plates (in the case of four plate materials 12 a to 12 d in the figure) in which the outer diameter D and the inner diameter d are gradually reduced in accordance with the cross-sectional shape of the buttress portion 10. Are stacked in parallel in a stepped manner with gaps S1, S2 and S3 between them. In the vulcanized tire, each of the gaps S is filled with a rubber material, and a plurality of plate members 12 are bonded to each other to form a laminated structural member 11, and the laminated structural member 11 is embedded and fixed in the rubber of the buttress portion 10. The The distance between the gaps S1, S2, and S3 is not particularly limited, but is, for example, about 0.2 to 3.0 mm, preferably 0.2 to 2.0 mm. If the distance between the gaps S is narrow, sufficient displacement between adjacent plate members cannot be obtained, and the amount of deformation in the longitudinal direction of the laminated structural member 11 is particularly small, making it difficult to control the rigidity. In addition, when the gap S is widened, the displacement between the plate members 12 increases, and in particular, the displacement between the plate members 12 is likely to vary during oblique input, which may reduce the steering stability. The distances between the gaps S1 to S3 may be equal or different.

  The laminated structural member 11 can be formed by laminating a plurality of plate materials 12 and sheet-like rubber materials alternately on the buttress portion 10 during tire molding.

  The laminated structural member 11 is formed in advance with a molded body formed by alternately laminating a plurality of annular plate materials 12 and a plurality of sheet-like rubber materials, and this molded body is disposed in the buttress portion 10 during tire molding. You can also

  In the laminated structural member 11, when an external force is input to the tire 1 in the tire radial direction, the axial direction, or both directions simultaneously, the laminated plate material 12 is displaced stepwise in the longitudinal and lateral directions within the laminated structural member 11. Thus, the longitudinal and lateral rigidity of the tire can be controlled independently. In particular, by facilitating displacement with respect to the tire radial direction input, it is flexible with respect to the tire radial direction input and rigid with respect to the axial input, so that The lateral deflection (rigidity) can be controlled to achieve both tire handling stability and ride comfort.

Further, the material of the plate material 12 is not particularly limited, but a material having a longitudinal elastic modulus (Young's modulus) in the range of 10 to 25,000 kgf / mm ² is preferable, and 1,000 to 25 is particularly preferable. Those in the range of 1,000 kgf / mm ² are preferred.

  Examples of the material of the plate material 12 in the range of the Young's modulus include metals such as carbon steel, stainless steel, alloy steel such as molybdenum, nickel, and chromium, soft iron, aluminum, aluminum alloy, copper, and lead.

  Further, as resins, polyamide resins (nylon 6, nylon 66, etc.), polyester resins (PET, PBN, PEN, etc.), polynitrile resins (PAN, AS, etc.), poly (meth) acrylate resins (PMMA, EEA) Etc.), thermoplastic resins such as polyvinyl resins (EVA, PVA, PVC, etc.), cellulose resins (cellulose acetate, etc.), fluororesins (polyvinylidene fluoride, polyvinyl fluoride, etc.), styrenes, olefins, etc. , Polyester-based, urethane-based, polyamide-based thermoplastic elastomers, and the like, and blend materials of these plural resins may be used.

  In addition, thermosetting resins such as urea resins, epoxy resins, and phenol resins can be used.

  Further, the resin may be a metal filament such as stainless steel or a reinforced plastic (MRP or FRP) reinforced with organic or inorganic fibers such as nylon, PET, glass fiber, or carbon fiber.

  The laminated structural member 11 may be formed by combining the plate materials made of the above two or more kinds of materials.

  The surface of the plate material 12 is for the purpose of improving the adhesiveness to rubber, physical surface treatment by polishing or blasting, application of adhesives such as various rubber pastes and resorcin-formaldehyde-latex liquid, brass and zinc It is preferable to perform metal plating treatment such as.

Here, the larger the difference between the Young's modulus of the plate material 12 and the rubber material disposed in the gap S, the better. Thereby, each plate member 12 is easily displaced between the layers of the laminated structural member 11 with respect to the input applied to the tire 1, and as a result, the laminated structural member 11 is easily bent, thereby making it easy to control the longitudinal rigidity and the lateral rigidity. . Since the Young's modulus of the vulcanized rubber material for tires is generally in the range of 0.1 to 0.5 kgf / mm ² , the Young's modulus of the plate material 12 is not less than 1,000 kgf / mm ² from this viewpoint. It is preferable. When the Young's modulus is less than 10 kgf / mm ^2, the laminated structure member 11 moves assimilating to the movement of the rubber of the buttress portion 10 and the effect of the present invention cannot be sufficiently obtained.

  Further, the arrangement angle in the tire radial direction of the annular plate member 12 in the laminated structural member 11 is a vertical line that is lowered from the tire rotation shaft to the ground surface when a specified internal pressure and maximum load are applied using a standard rim specified by JIS. It is preferable to arrange in the range of 0 ± 10 °.

  When the arrangement angle of the plate material 12 deviates from the range of ± 10 ° with respect to the vertical line, the radial and axial inputs to the tire 1 are inclined with respect to the laminated structural member 11, Particularly, the damping performance of the laminated structural member 11 with respect to the longitudinal input is lowered, and it becomes difficult to obtain a balance between the longitudinal rigidity and the lateral rigidity of the tire 1.

  Further, in the present invention, as in the tire 20 shown in FIG. 5, at least one carcass ply of the carcass 6 is divided on the tire circumference at the position of the laminated structure member 11, and the carcass ply divided end portion is the tire circumference. It may be sandwiched in the gap S between the annular plate members 12 of the laminated structural member 11.

  The tire 20 shown in FIG. 5 is a tire in which the carcass 6 has a two-ply structure, and in the carcass ply, the 2nd ply 62 is divided on the tire circumference at the position of the laminated structural member 11 on both sides of the tire. The ply split end portion 62a is sandwiched between the plate members 12b and 12c on the tire circumference, and the ply split end portion 62b on the side wall portion 3 side is sandwiched between the plate members 12c and 12d. The 2nd ply 62 of the carcass 6 is integrally formed through the. In the example shown in the figure, the 1st ply 61 forms a continuous carcass without being divided at the position of the laminated structure member 11, but the 1st ply 61 can also have a divided structure in the same manner as the 2nd ply. .

  As described above, the carcass ply is divided at the portion of the laminated structural member 11, so that the ride comfort can be further improved by increasing the amount of deformation of the buttress portion 10 in the vertical direction.

  Further, in the tires 1 and 20 of the present invention, the laminated structural member 11 has a side portion in the vicinity of the maximum tire width W that has contributed to the conventional tire deformation by making the longitudinal deformation amount of the buttress portion 10 larger than the conventional one. Thus, the effect of suppressing the decrease in the carcass tension of the side portion can be obtained, and the handle responsiveness during cornering is excellent.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the examples.

Laminated structure member in which the tire size is 215 / 60R16 (rib pattern of 4 main grooves), and a rubber material having a thickness of 0.5 mm is alternately arranged between four plate materials having a thickness of 0.5 mm. Tires of Examples 1 to 4 shown in FIG. 2 and FIG. In the plate materials of Examples 1 and 2, a carbon steel sheet containing 0.33% carbon (Young's modulus 210,000 kgf / mm ² ), the plate material of Example 3 is an aluminum alloy (Young's modulus 6,000 kgf / mm ² ), As the plate material of Example 4, nylon 6 resin (Young's modulus 110 kgf / mm ² ) was used. The comparative example tire is a tire having a conventional structure shown in FIG.

  The longitudinal stiffness and lateral stiffness were measured under the conditions of a used rim 16 × 6.5 JJ, an air pressure of 200 kPa, a longitudinal load of 480 kgf, and a lateral load of 120 kgf. Longitudinal and lateral rigidity can be obtained by adding load in the direction (kgf) / deformation amount in the direction (mm).

  Further, as the ground contact characteristics, the tread contact length and the average contact pressure on the tire contact surface when a longitudinal load was applied and when a (longitudinal load + lateral load) was applied were measured. The tread grounding shapes of Examples 1 and 2 are illustrated in FIGS. 6 shows a tread contact shape when a longitudinal load of 480 kgf is applied, and FIG. 7 shows a tread contact shape when a longitudinal load of 480 kgf and a lateral load of 120 kgf (the lateral load is added from the right side in the figure) are applied simultaneously. The grounding length) and average grounding pressure (additional load / grounding area) are based on these grounding shapes, tread center part (indicated as C part) and shoulder part (the lateral load addition side is A part, and the opposite side is B part. Display). All are shown in index notation with index 100 based on the comparative example.

  Next, four tires were mounted on a vehicle (a domestic passenger car with a displacement of 2500 cc, FR type), and steering stability and ride comfort were evaluated under the following conditions. The results are shown in Table 1.

  The carcass of each tire is 2 plies of polyester cord 1,100 dtex / 2 (drive density 23/25 mm), the belt is steel cord 2 + 2 × 0.25 mm (drive density 25/25 mm) 2 plies, and the cap ply is One ply of nylon 66 cord 940 dtex / 2 (injection density of 21/25 mm) was used, and was the same in the examples and comparative examples.

[Steering stability]
In the test course (asphalt dry road surface) for handling stability evaluation owned by the applicant, it is possible for three test drivers to feel the straightness, lane change, and cornering handling at 80-100 km / h. Overall evaluation and averaged. The comparative example is indicated by an index display with an index of 100. The higher the index, the better.

[Ride comfort]
Drive the three types of test courses of the applicant's good road, rough road and bump step road at a speed of 60 km / h. Overall, they were evaluated by the feeling of three test drivers, and the average was taken. The comparative example is indicated by an index display with an index of 100. The higher the index, the better.

  As shown in Table 1, in the comparative example tire, when the longitudinal stiffness is increased, the lateral stiffness is also increased accordingly (the lateral stiffness / longitudinal stiffness is a value close to 0.5). In the tire No. 4, the increase rate of the longitudinal rigidity and the lateral rigidity can be changed, and the increase in the lateral rigidity is obtained with respect to the increase in the longitudinal rigidity, and the lateral rigidity / the longitudinal rigidity can be controlled.

  That is, from Table 1 and FIGS. 6 and 7, there is no significant change in the grounding characteristics with only the longitudinal load applied in each example, and the tire characteristics during normal running of the vehicle are similar between the tires of the comparative example and the examples. It is judged that On the other hand, when the vertical and lateral loads are applied, the ground contact shape of the tire generally changes to a trapezoidal shape. However, in the example tire, the contact length of the comparative tire becomes shorter (the B portion side shoulder portion). The contact length is maintained, and similarly, the increase in the contact length on the side where the contact length of the comparative tire becomes longer (the A-side shoulder portion) is kept small compared to the comparative example. This indicates that the cornering characteristics of the example tires are excellent.

  As a result, as can be seen from the evaluation results of steering stability and riding comfort, a significant increase in handling stability can be obtained, while there is a small reduction in riding comfort, with a good balance between handling stability and riding comfort. The tire to be made compatible can be easily estimated by adopting the laminated structure member according to the present invention and designing the Young's modulus, dimension and shape of the plate material, the number of laminated sheets, and the like.

  The present invention can be applied to pneumatic tires for various sizes and uses such as for passenger cars, light trucks, large tires for buses and trucks.

It is a half sectional view of the pneumatic tire of an embodiment. It is an expanded sectional view of the buttress part of a tire same as the above. It is the front view and side view of a plate material. It is a side view of a laminated structure member. It is an expanded sectional view of the buttress part of the tire of other embodiments. It is explanatory drawing of the tread grounding shape at the time of a longitudinal load addition. It is explanatory drawing of the tread grounding shape at the time of a vertical load and a lateral load addition. It is a half sectional view of a pneumatic tire of a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire 2 ... Tread part 3 ... Side wall part 4 ... Bead part 5 ... Bead core 6 ... Carcass 7 ... Belt 10 ... Buttress part 11 ... Laminated structural member 12 ... Plate material W: Maximum width of tire

Claims (4)

A bead portion having a pair of bead cores, a sidewall portion extending outward in the tire radial direction from the bead portion, and a tread portion provided between the sidewall portions, and between the pair of bead portions In a pneumatic tire in which a carcass composed of at least one layer of carcass ply mounted and a belt composed of at least two layers of belt ply are arranged on the outer peripheral side of the tread portion of the carcass,
A laminated structural member in which a plurality of annular plate materials and rubber materials are alternately arranged and laminated in the buttress portion on the outer side in the tire radial direction of the carcass between the outer ends of both ends of the belt and the maximum tire width portion. Pneumatic tire characterized by that. ^2. The pneumatic tire according to claim 1, wherein the plate member has a longitudinal elastic modulus in a range of 10 to 25,000 kgf / mm ² . 3. The pneumatic according to claim 1, wherein an arrangement angle of the plate material in a tire radial direction is in a range of 0 ± 10 ° with respect to a vertical line extending from the tire rotation axis to the ground contact surface. tire. At least one carcass ply of the carcass is divided on the tire circumference at the position of the laminated structural member, and the carcass ply dividing end portion is sandwiched between the annular plate members on the tire circumference. The pneumatic tire according to any one of claims 1 to 3.

Images