Pneumatic tire

Abstract

The present invention addresses the problem of maintaining the uniformity of a tire and the durability of a muffler body in a pneumatic tire in which the muffler body is disposed in a tire cavity. A pneumatic tire according to the present invention includes a tire inner cavity (1B) and a porous silencer (10). The silencing body (10) is an annular body extending in the tire circumferential direction and is not fixed to the surface of the tire inner cavity (1B). The average thickness T (mm) and the inner cavity surface radius R (mm) of the silencing body (10) satisfy the following formula (1). In a state in which the muffler body (10) is removed from the pneumatic tire, the average circumferential length L (mm) of the muffler body (10) in the circumferential direction and the circumferential length C (mm) of the inner cavity surface satisfy the following formulae (2) and (3). 0.04 < = T / R < = 0.18 (1) 1.02-1.1 * T / R < = L / C < = 0.95-1.4 * T / R (2) L / C < = 1.1 (3).

Description

Technical Field

[0001] The present invention relates to pneumatic tires. Background Art

[0002] Patent Document 1 below proposes a pneumatic tire with a silencer having a silencer made of an annular sponge material on the inner surface of the tire. In this pneumatic tire, the silencer can be attached to the inner surface of the tire without using an adhesive. [Prior art literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2012-111382 Summary of the invention [Problems to be solved by the invention]

[0004] For example, in the tire of Patent Document 1, when the porous silencer is configured to be not fixed to the inner surface of the tire, depending on the circumferential length and thickness of the silencer, as the tire travels, part of the silencer will bulge inward in the radial direction of the tire to produce so-called buckling, which may lead to deterioration of the uniformity of the tire and reduction in the durability of the silencer.

[0005] The present invention has been proposed in view of the above-mentioned actual situation, and a main object of the present invention is to maintain the uniformity of the tire and the durability of the silencer in a pneumatic tire in which a silencer is arranged in the inner cavity of the tire.

Methods for solving the problem

[0006] The present invention is an inflatable tire, comprising an inner cavity of the tire and a porous silencer arranged in the inner cavity of the tire; the silencer is an annular body extending along the circumferential direction of the tire and is not fixed to the surface of the inner cavity of the tire; the silencer has a circumferential direction of the annular body and a thickness direction in the same direction as the radial direction of the annular body; the average thickness T (mm) and the inner cavity surface radius R (mm) of the silencer satisfy the following formula (1), the inner cavity surface radius R (mm) is the distance in the radial direction of the tire from the tire rotation axis on the tire equatorial plane to the surface of the inner cavity of the tire; when the silencer is removed from the inflatable tire, the average circumference L (mm) of the silencer in the circumferential direction and the inner cavity surface circumference C (mm) satisfy the following formulas (2) and (3), the inner cavity surface circumference C (mm) is the tire circumferential length of the surface of the inner cavity of the tire on the tire equatorial plane. 0.04≤T / R≤0.18…(1) 1.02-1.1×T / R≤L / C≤0.95+1.4×T / R…(2) L / C≤1.1…(3) [Effects of the invention]

[0007] The pneumatic tire of the present invention can maintain uniformity and durability of the silencer by adopting the above-mentioned structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008]

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Figure 8

[0009] Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings. The accompanying drawings contain and record the features of the present invention, but in order to facilitate understanding of the present invention, the accompanying drawings sometimes include exaggerated expressions or expressions that are different from the actual structural dimension ratios. In addition, in each embodiment, the same or common elements are represented by the same symbols, and repeated descriptions are omitted.

[0010] Figure 1 1 is a tire meridian cross-sectional view showing a pneumatic tire (hereinafter sometimes simply referred to as a "tire") 1 in a normal state according to an embodiment of the present invention. Figure 1 1 shows a cross-sectional view of the tire 1 when the tire 1 extending in a circular shape passes through the tire rotation axis and is cut in a virtual plane orthogonal to the tire circumferential direction. Figure 1As shown, in this embodiment, a pneumatic tire 1 for a passenger car is shown. However, the present invention can also be applied to a pneumatic tire 1 for heavy loads, for example.

[0011] In the case of pneumatic tires with various specifications specified, the "normal state" refers to a state in which the tire is mounted on a normal rim, filled with a normal internal pressure, and is unloaded. In the case of tires with various specifications not specified, the normal state refers to a standard usage state corresponding to the intended use of the tire, a state in which the tire is not mounted on a vehicle and is unloaded. In this specification, unless otherwise specified, the dimensions of various parts of the tire are values ​​measured under the normal state. In addition, the dimensions of structures that cannot be measured under the normal state (for example, the internal materials of the tire 1) are values ​​measured in a state in which the tire 1 is as close to the normal state as possible.

[0012] "Regular rim" refers to the rim specified for each tire in the specification system including the specification to which the tire is based. For example, it refers to "standard rim" in JATMA, "design rim" in TRA, and "measuring rim" in ETRTO.

[0013] "Normal internal pressure" refers to the air pressure specified for each tire in the specification system that includes the specifications to which the tire is based. In JATMA, it refers to the "maximum air pressure", in TRA, it refers to the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLDINFLATION PRESSURES", and in ETRTO, it refers to "INFLATION PRESSURE".

[0014] The tire 1 of the present embodiment is installed on a vehicle equipped with a puncture repair kit including a puncture sealant, for example. The puncture repair kit performs puncture repair by injecting a puncture sealant from the air valve of the tire with a puncture. The puncture sealant injected into the interior of the tire can solidify when passing through the puncture hole to block it. In addition, the tire 1 of the present invention can perform puncture repair by injecting the puncture sealant into the interior of the tire from the air valve as described above. Therefore, the tire 1 of the present embodiment has a degree of rigidity on the tread portion 2 that the blocked puncture hole will not open again even if the vehicle is driven after the puncture repair. Specifically, it has at least the following carcass 6 and belt layer 7.

[0015] The carcass 6 extends from the bead portion 4 on one side through the sidewall portion 3 on one side, the tread portion 2, and the sidewall portion 3 on the other side to the bead portion 4 on the other side. In addition, the carcass 6 has at least one carcass cord 6A, and in this embodiment, two carcass cords. The carcass cords are formed by, for example, covering the arrangement of carcass cords with topping rubber. The carcass cords are arranged at an angle of 75 to 90 degrees relative to the tire circumferential direction. For example, organic fibers such as polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers can be used for the carcass cords.

[0016] The carcass ply 6A includes, for example, a main body 6a and a folded portion 6b. The main body extends from the tread portion 2 through the sidewall portion 3 to the bead core 5. The folded portion 6b is connected to the main body 6a, folded around the bead core 5 from the inner side to the outer side in the tire axial direction, and extends outward in the tire radial direction.

[0017] The belt layer 7 is arranged on the tread portion 2 on the outer side of the carcass 6 in the tire radial direction. The belt layer 7 includes at least one belt ply, and the belt layer 7 of this embodiment is composed of two belt plies 7A and 7B. The belt plies 7A and 7B are formed by, for example, covering an array of belt cords with a topping rubber.

[0018] The tire 1 of the present invention includes a tire inner cavity 1B, a pneumatic tire body 1A that fixes the tire inner cavity 1B, and a porous sound absorbing body 10 disposed in the tire inner cavity 1B. Figure 2 Displayed Figure 1 An enlarged perspective view of the pneumatic tire body 1A and the muffler 10. Figure 1 and Figure 2 As shown, the silencer 10 can absorb air vibrations inside the tire 1 during running, and helps reduce the noise generated by the tire.

[0019] The silencer 10 of the present invention is an annular body extending in the circumferential direction of the tire and is not fixed to the surface 1s of the tire inner cavity 1B. That is, the tire 1 of the present invention does not use an adhesive for fixing the silencer 10, so it is light in weight and the installation workability of the silencer 10 is excellent when the tire is manufactured. Moreover, when the tire 1 of the present invention is punctured, when trying to repair the puncture with a puncture sealant, since the silencer 10 is not fixed to the surface of the tire inner cavity 1B, the puncture sealant easily enters the puncture hole, and can exert excellent puncture repairability.

[0020] The silencer 10 includes the circumferential direction of the annular body, the thickness direction in the same direction as the radial direction of the annular body, and the width direction orthogonal to the thickness direction and the circumferential direction. In the present embodiment, the circumferential direction of the silencer 10 is substantially consistent with the circumferential direction of the tire. In addition, the thickness direction of the silencer 10 is substantially consistent with the radial direction of the tire. In addition, the width direction of the silencer 10 is substantially consistent with the axial direction of the tire. Here, the "substantially consistent" includes that the angle difference between the circumferential direction, the thickness direction or the width direction and the circumferential direction of the tire, the radial direction of the tire or the axial direction of the tire is less than 5°.

[0021] like Figure 1 As shown, in the present invention, the average thickness T (mm) and the inner cavity surface radius R (mm) of the muffler 10 satisfy the following formula (1), wherein the inner cavity surface radius R (mm) is the distance in the tire radial direction from the tire rotation axis in the tire equatorial plane Cs to the surface 1s of the tire inner cavity 1B. In addition, the average thickness T is obtained by virtually dividing the muffler 10 into a plurality of micro-areas including the outer side surface and the inner side surface in the thickness direction, measuring the thickness of each micro-area, and dividing the sum of the thicknesses of each micro-area by the number of the micro-areas. 0.04≤T / R≤0.18…(1)

[0022] In addition, in the present invention, when the silencer 10 is removed from the tire 1, the average circumference L (mm) of the silencer 10 in the circumferential direction and the inner cavity surface circumference C (mm) satisfy the following equations (2) and (3), wherein the inner cavity surface circumference C (mm) is the tire circumferential length of the surface 1s of the tire inner cavity 1B in the tire equatorial plane Cs. In addition, the circumference L is the circumference L obtained by virtually dividing the silencer 10 into a plurality of micro-annular bodies, measuring the circumference of each micro-annular body, and dividing the sum of the circumferences of the obtained micro-annular bodies by the number of the micro-annular bodies. 1.02-1.1×T / R≤L / C≤0.95+1.4×T / R…(2) L / C≤1.1…(3)

[0023] The tire 1 of the present invention can maintain the uniformity of the tire and the durability of the silencer 10 by having the above-mentioned features. The reason for this is as follows.

[0024] Generally speaking, if the length of the silencer is small, the position in the tire cavity is unstable, and it is difficult to maintain the shape of the silencer. In addition, if the length of the silencer is large, it is easy to deform such as buckling. Due to such defects, the uniformity of the tire may deteriorate, or the silencer may be damaged by friction with the surface of the tire cavity and the rim. Therefore, in order to maintain the uniformity of the tire and the durability of the silencer, it is important to control the length of the silencer within an appropriate range.

[0025] In addition, if the thickness of the silencer is small, it is difficult to maintain its shape (ring-shaped body). In addition, if the thickness of the silencer is large, it is easy to apply a large stress to the silencer, so as the tire runs, it is easy to cause defects such as damage and wear of the silencer. Therefore, in order to maintain the uniformity of the tire and the durability of the silencer, it is important to consider not only the length of the silencer but also the thickness of the silencer and control these dimensions within an appropriate range.

[0026] The inventors conducted various experiments based on the above findings. Figure 3 As a graph showing the above experimental results, the relationship between the size of the silencer and the occurrence of damage to the silencer, etc. is shown. Figure 3 In the figure, the horizontal axis is the ratio T / R of the average thickness T of the muffler to the radius R of the inner cavity surface. The vertical axis is the ratio L / C of the circumference L of the muffler to the circumference C of the inner cavity surface.

[0027] The inventors prepared silencers with appropriately changed T / R and L / C, and test tires equipped with these silencers. In addition, the inventors evaluated the durability of the silencers in these test tires. This evaluation was performed by dropping the tire equipped with the silencer from a height of 1m to the ground to confirm whether the silencer fell off (hereinafter referred to as the "drop test"), and then using a drum tester to drive the test tire for a certain distance to confirm whether the silencer was misaligned or damaged. This is a comprehensive evaluation. Figure 3 In the figure, "○", "△" and "×" are the evaluation results of the durability of each test tire. "○" means that the silencer has no misalignment or damage and is in good condition. "△" means that the silencer has no problem in use, but has slight misalignment or damage. "×" means that the silencer is easy to fall off in the drop test, or the silencer is too large and damages the durability and uniformity, etc., which need to be improved.

[0028] The results showed that Figure 3 As shown, within a certain range ( Figure 3 Good results were obtained in the coordinates within the range of 1.5°. Further analysis of the results revealed that the specific range was caused by Figure 3 The area surrounded by the dotted curves G1 to G5 in FIG. Curve G1: T / R = 0.04 Curve G2: T / R = 0.18 Curve G3: L / C = 1.02-1.1×T / R Curve G4: L / C = 0.95 + 1.4 × T / R Curve G5: L / C = 1.1

[0029] In addition, the inventors have experimentally confirmed that even if the type of silencer, tire size and other conditions are changed, good results can be obtained within the specific range, thereby completing the present invention. That is, in the present invention, by setting the size of the silencer 10 to a specific range (satisfying the range of the above formulas (1) to (3)), the uniformity of the tire 1 and the durability of the silencer 10 can be maintained.

[0030] In a preferred embodiment, any one of the following formulas (4) to (6) is satisfied, and any two of them are more preferably satisfied. In a further preferred embodiment, all of the following formulas (4) to (6) are satisfied. Thus, the above-mentioned effects can be surely exerted. 0.06≤T / R≤0.16…(4) 1.04-1.1×T / R≤L / C≤0.94+1.4×T / R…(5) L / C≤1.08…(6)

[0031] The following describes a more detailed structure of the present embodiment. It should be noted that the various structures described below show specific aspects of the present embodiment. Therefore, even if the present invention does not have the structures described below, it can still achieve the effects described above. In addition, in the tire of the present invention having the above characteristics, even if only any one of the various structures described below is applied alone, it can be expected that the performance corresponding to each structure will be improved. Furthermore, when several of the various structures described below are applied in combination, it can be expected that the composite performance corresponding to each structure will be improved.

[0032] Unless otherwise specified, the dimensions of the silencer 10 described below are measured when the tire 1 is not mounted on the rim, the distance between the pair of bead cores 5 is consistent with the normal state, and the silencer 10 is arranged in the tire inner cavity 1B.

[0033] like Figure 1 As shown, the muffler 10 is made of, for example, a porous sponge material. For example, a sponge material having continuous bubbles formed by foaming rubber or synthetic resin is used. In a preferred embodiment, the muffler 10 is made of a polyurethane sponge having both an ether bond and an ester bond. However, the present invention is not limited to this embodiment.

[0034] When the air permeability of the muffler 10 reaches a certain range, when the tire 1 is repaired with a puncture sealant, the muffler 10 will continue to absorb the puncture sealant, making it difficult for the puncture sealant to reach the puncture hole. Based on this viewpoint, the air permeability of the muffler 10 is preferably 27 ml / cm 2 / s or less. Thus, the above-mentioned defects can be suppressed. In addition, the air permeability is measured in accordance with JIS K6400-7.

[0035] If the air permeability of the silencer 10 is high, even if the silencer 10 absorbs the puncture sealant, it is easy to discharge it again, which can suppress the above-mentioned defects. Based on this point of view, the air permeability of the silencer 10 can also be, for example, 62 ml / cm 2 / s or more.

[0036] The density of the silencer 10 is, for example, 5 to 60 kg / m 3 , preferably 10 to 50 kg / m 3 . Such a silencer 10 can exert an excellent silencer effect while suppressing an increase in tire weight. In addition, the hardness of the silencer 10 is 20 to 120 N, preferably 40 to 100 N. Thus, it is possible to suppress the misalignment of the silencer 10 while maintaining the installation workability of the silencer 10 during tire manufacturing. Here, the hardness of the silencer 10 refers to the value measured by the D method in Item 6.7 of the measurement method in Item 6 of JIS K6400.

[0037] like Figure 2 As shown, the silencer 10 is positioned to intersect with the tire equatorial plane Cs. The silencer 10 is in contact with (but not fixed to) the surface of the tread portion 2 on the tire inner cavity 1B side. In addition, in the silencer 10, the cross section orthogonal to the tire circumferential direction is a rectangle. In a preferred embodiment, the cross section of the silencer 10 is a transverse rectangle in the tire axial direction. In addition, almost the entirety (more than 80%) of the silencer 10 in the circumferential direction is in contact with the tire inner cavity 1B. Such a silencer 10 can exert excellent noise reduction effect and durability.

[0038] Figure 4 Shown is an enlarged cross-sectional view of the muffler body 10. Figure 4 As shown, the maximum thickness t1 of the silencer 10 in the radial direction of the tire is 10 to 40 mm. In addition, the maximum width W1 of the silencer 10 is the cross-sectional width Wt of the tire 1 ( Figure 1 The muffler 10 is 20% to 80% of the pneumatic tire body 1A, preferably 20% to 40%. The muffler 10 is difficult to separate from the pneumatic tire body 1A during tire running. Therefore, the wear of the muffler 10 is suppressed.

[0039] The cross-sectional area of ​​the muffler 10 (cross-sectional area in the tire meridian cross section) is 3 to 20% of the cross-sectional area of ​​the tire 1 excluding the muffler 10. Therefore, an excellent muffler effect can be obtained while suppressing an increase in tire weight.

[0040] Figure 5 A conceptual diagram of the side view of a tire 1 is shown. Figure 5 In FIG. 1 , the muffler 10 is indicated by a dotted line. Figure 5 As shown, the two ends of the silencer 10 in the tire circumferential direction of the present embodiment are bonded to each other to form the annular body. Figure 5In the embodiment, glue is applied to the bonding portions 13 at both ends. Such a silencer 10 can suppress wear caused by contact between the ends of the silencer 10 and the rim, etc., and can obtain excellent durability.

[0041] Both ends of the muffler 10 are fixed by, for example, an adhesive. In other embodiments, the two ends may be welded (bonded by heating and melting the sponge material).

[0042] Figure 6 FIG. 2 further shows an enlarged view of the circumferential ends of the muffler 10 according to another embodiment. Figure 6 As shown, the muffler 10 of this embodiment has a fitting portion 20 that fits the convex portion 16 provided at one circumferential end and the concave portion 17 provided at the other circumferential end. Therefore, the muffler 10 can be made into an annular body without using an adhesive or the like, and the uniformity of the tire is further improved.

[0043] Figure 7 FIG. 2 further shows an enlarged view of the circumferential ends of the muffler 10 according to another embodiment. Figure 7 As shown, in the muffler 10 of this embodiment, a plurality of convex portions 16 are provided at one end in the circumferential direction, and a plurality of concave portions 17 are provided at the other end in the circumferential direction. The convex portion 16 is, for example, cylindrical, and the concave portion 17 has an inner shape corresponding to the convex portion 16. The fitting portion 20 having such convex portions 16 and concave portions 17 can suppress deformation of the muffler 10 in the thickness direction.

[0044] Figure 8 The enlarged view of the two ends of the circumferential direction of the muffler 10 of another embodiment is shown. Figure 8 As shown, in the muffler 10 of this embodiment, the convex portion 16 and the concave portion 17 are respectively provided at one end and the other end in the circumferential direction. The convex portion 16 is, for example, cylindrical, and the concave portion 17 has an internal shape corresponding to the convex portion 16. In this embodiment, even if multi-directional stress acts on the fitting portion 20, the convex portion 16 is difficult to be separated from the concave portion 17, and excellent durability can be exhibited.

[0045] Although some embodiments of the pneumatic tire of the present invention have been described in detail above, the present invention is not limited to the above embodiments and can be implemented by changing into various forms.

[0046] [Notes] The present invention includes the following aspects.

[0047] [Present invention 1] A pneumatic tire, The invention comprises a tire inner cavity and a porous sound-absorbing body arranged in the tire inner cavity. The muffler is an annular body extending along the circumferential direction of the tire and is not fixed to the surface of the inner cavity of the tire. The muffler includes a circumferential direction of the annular body and a thickness direction which is the same direction as the radial direction of the annular body. The average thickness T (mm) and the inner cavity radius R (mm) of the muffler satisfy the following formula (1), wherein the inner cavity radius R (mm) is the distance in the tire radial direction from the tire rotation axis of the tire equatorial plane to the surface of the tire inner cavity, When the silencer is removed from the pneumatic tire, the average circumference L (mm) of the silencer in the circumferential direction and the inner cavity surface circumference C (mm) satisfy the following equations (2) and (3), wherein the inner cavity surface circumference C (mm) is the tire circumferential length of the surface of the tire inner cavity on the tire equatorial plane. 0.04≤T / R≤0.18…(1) 1.02-1.1×T / R≤L / C≤0.95+1.4×T / R…(2) L / C≤1.1…(3) [Present invention 2] According to the pneumatic tire of the present invention 1, the silencer has a width direction orthogonal to the thickness direction and the circumferential direction of the annular body. The maximum width of the muffler is 20% to 80% of the cross-sectional width of the pneumatic tire. [Present invention 3] In the pneumatic tire according to Invention 2, the noise absorbing body is positioned to intersect with the tire equatorial plane. [Present invention 4] In the pneumatic tire according to any one of Inventions 1 to 3, both ends of the silencer in the circumferential direction are bonded to each other to form the annular body. [Present invention 5] According to the pneumatic tire of any one of Inventions 1 to 3, the silencer has a fitting portion in which a convex portion provided at one end in the circumferential direction fits with a concave portion provided at the other end in the circumferential direction. [Present invention 6] In the pneumatic tire according to any one of Inventions 1 to 5, the sound absorbing body has a rectangular cross section. [Present invention 7] According to any one of the first to sixth aspects of the present invention, the density of the silencer is 5 to 60 kg / m 3 . [Present invention 8] In the pneumatic tire according to any one of Inventions 1 to 7, the hardness of the silencer is 20 to 120N. [Present invention 9] In the pneumatic tire according to any one of Inventions 1 to 3, the cross-sectional area of ​​the silencer is 3 to 20% of the cross-sectional area of ​​the pneumatic tire after removing the silencer.

Claims

1. A pneumatic tire, characterized in that: The invention comprises a tire inner cavity and a porous sound-absorbing body arranged in the tire inner cavity. The muffler is an annular body extending along the circumferential direction of the tire and is not fixed to the surface of the inner cavity of the tire. The silencer has: a circumferential direction of the annular body and a thickness direction which is the same direction as the radial direction of the annular body. The average thickness T and the inner cavity radius R of the muffler satisfy the following formula (1), wherein the inner cavity radius R is the distance from the tire rotation axis of the tire equatorial plane to the surface of the tire inner cavity in the tire radial direction, and the average thickness T and the inner cavity radius R of the muffler are in units of mm, When the silencer is removed from the pneumatic tire, the average circumference L of the silencer in the circumferential direction and the circumference C of the inner cavity surface satisfy the following equations (2) and (3), wherein the circumference C of the inner cavity surface is the circumferential length of the surface of the tire inner cavity on the tire equatorial plane, and the units of the average circumference L of the silencer in the circumferential direction and the circumference C of the inner cavity surface are mm. 0.04≤T / R≤0.18…(1) 1.02-1.1×T / R≤L / C≤0.95+1.4×T / R…(2) L / C≤1.1…(3).

2. The pneumatic tire according to claim 1, wherein: The muffler has a width direction perpendicular to the thickness direction and the circumferential direction of the annular body. The maximum width of the muffler is 20% to 80% of the cross-sectional width of the pneumatic tire.

3. The pneumatic tire according to claim 2, wherein: The muffler is positioned to intersect the tire equatorial plane.

4. The pneumatic tire according to claim 1 or 2, wherein: Both ends of the muffler in the circumferential direction are bonded to each other to form the annular body.

5. The pneumatic tire according to claim 1 or 2, wherein: The muffler has a fitting portion in which a convex portion provided at one end in the circumferential direction is fitted with a concave portion provided at the other end in the circumferential direction.

6. The pneumatic tire according to claim 1 or 2, wherein: The cross section of the muffler is rectangular.

7. The pneumatic tire according to claim 1 or 2, wherein: The density of the muffler is 5 to 60 kg / m 3 .

8. The pneumatic tire according to claim 1 or 2, wherein: The hardness of the silencer is 20 to 120 N. The hardness of the silencer is a value measured by the D method in accordance with the measurement method in item 6.7 of JIS K6400.

9. The pneumatic tire according to claim 1 or 2, wherein the cross-sectional area of ​​the silencer body is 3 to 20% of the cross-sectional area of ​​the pneumatic tire after removing the silencer body.

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