JP2006264652A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a tire by preventing peeling of a carcass in a base part of a partition wall in a pneumatic tire having three air chambers. <P>SOLUTION: An outside carcass 21 wound around an outside bead part 12 and an inside carcass 22 wound around an inside bead part 24 are not overlapped each other in an under layer of a tread part 16 between a pair of right and left partition walls 18. Consequently, a peeling input for the overlapped part of the inside carcass 22 and the belt layer 40 is reduced, the peeling progress is suppressed, and an early failure of the tire can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire in which a plurality of tire air chambers are formed when mounted on a rim.

The conventional tire chamber that can be filled with air obtained when a general tire is mounted on a rim has been one chamber, but at least one partition wall is provided on the inner side of the tire and is independent from the rim. Tires in which a plurality of tire air chambers are formed have also been developed (see Patent Document 1).
JP 2003-39914 A

  By the way, in the pneumatic tire in which a plurality of air chambers (for example, a central main air chamber and its left and right sub air chambers) are formed by providing a partition wall as in the conventional example described above, Due to the bending or the like, a force that causes separation between the carcasses that overlap each other acts on the base that is the connecting portion between the partition wall and the tire case. The magnitude of this peeling input is a factor that greatly affects the durability performance of the tire, especially when the main air chamber is punctured by nailing, etc. and the internal pressure becomes 0, and it is necessary to support the load in the sub air chamber, etc. In this case, the peeling input becomes a problem.

  However, the above-described conventional example only discloses that a plurality of tire air chambers are formed by providing the partition walls, and does not suggest any countermeasure against the peeling input.

  In view of the above facts, an object of the present invention is to improve the durability of a tire in a pneumatic tire having three air chambers by preventing separation of the carcass at the base of the partition wall.

  In a pneumatic tire that has two partition walls and a total of three air chambers, one main air chamber and two sub air chambers, are formed when the rim is mounted, the main air chamber inside the tire width direction is mainly the belt tension. The first auxiliary air chamber and the second auxiliary air chamber located on both sides in the tire width direction share the carcass tension of the sidewall part, and the internal pressure of each air chamber can be set independently. It is.

  For this reason, for example, by setting the internal pressure of the main air chamber to be lower than the normal internal pressure of the conventional tire and setting the internal pressure of the first sub air chamber and the second sub air chamber to be higher than the normal internal pressure of the conventional tire, It is possible to control the balance of tire stiffness, which is impossible with conventional tires, such as increasing the lateral stiffness (lateral spring) while lowering the stiffness (vertical spring).

  However, as a result of research conducted by the inventor of the present application, in a pneumatic tire having three air chambers, at the time of high-speed traveling or the like, at least one of the sidewall portion and the tread portion and the partition wall are connected to the base portion of the partition wall. A force (peeling input) that causes the carcass to peel off acts on the overlapping portion. However, the peeling input is larger than the internal pressure combination condition in which the main air chamber pressure = the sub air chamber pressure. It was found that the internal pressure was smaller than the internal pressure combined condition of the sub-air chamber pressure, and this large separation input caused early tire failure.

  Accordingly, the invention of claim 1 includes a pair of left and right outer bead portions in which bead cores are embedded, a sidewall portion extending outward in the tire radial direction from the outer bead portion, a tread portion connected to the sidewall portion, The outer bead portion is provided between the pair of outer bead portions so as to be spaced apart in the tire width direction, and extends inward in the tire radial direction from a base portion on the tire inner surface side in at least one of the sidewall portion and the tread portion, A pair of left and right partition walls that form an independent three air chamber in the tire width direction between the inner bead portion provided at the inner end in the tire radial direction and the rim, and when the inner bead is attached to the rim. A pneumatic tire having an outer carcass wound around the outer bead portion and an inner carcass wound around the inner bead portion. Is characterized in that do not overlap each other in the lower layer of the tread portion between the partition wall.

  Here, the reason why the outer carcass and the inner carcass do not overlap each other in the lower layer of the tread portion between the pair of left and right partition walls is that, in particular, a part of the outer carcass is sandwiched between the inner carcass and the belt layer. In such a case, the peeling input to the overlapping portion of the inner carcass and the belt layer becomes large, and the peeling progress at this portion causes an early failure of the tire.

  In the pneumatic tire according to claim 1, since the outer carcass and the inner carcass do not overlap with each other in the lower layer of the tread portion between the pair of left and right partition walls, the inner carcass and the belt layer are formed between the outer carcass and the inner carcass. Since the peeling input to the overlapping portion is reduced and the peeling progress is suppressed, early tire failure can be prevented.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, an overlap portion where the outer carcass and the inner carcass overlap each other is in the partition wall and / or the region on the outer bead portion side from the base portion. It is characterized by being formed inside.

  The pneumatic tire according to claim 2, wherein the overlap portion forms the first sub air chamber and the second sub air chamber in the partition wall and / or in the region from the base portion to the outer bead portion side, that is, when the rim is mounted. Since each case is located, the strength of the tire case around the auxiliary air chamber can be increased, and the internal pressure combination in which the first auxiliary air chamber pressure and the second auxiliary air chamber pressure are higher than the main air chamber pressure. Sufficient durability that can be used even under conditions can be obtained.

  According to a third aspect of the present invention, in the pneumatic tire according to the second aspect, the length of the overlap portion is 10 mm or more.

  The overlap portion increases the strength of the tire case around these auxiliary air chambers, particularly considering the internal pressure combination condition that makes the first auxiliary air chamber pressure and the second auxiliary air chamber pressure higher than the main air chamber pressure. It is intended to maintain the sub-air chamber pressure, but when a high-speed durability test was conducted with an indoor drum tester, the overlap amount was too small when the length of the overlap portion was less than 10 mm. As a result, it has been found that there are many cases in which the pressure inside the sub-air chamber cannot be maintained, and blowout failures occur from the overlap portion. For this reason, the length of an overlap part needs to be 10 mm or more. More preferably, the length of the overlap portion is 30 mm or more.

  The invention according to claim 4 is the pneumatic tire according to claim 1, wherein the outer carcass and the inner carcass are at least one continuous carcass ply.

  In the pneumatic tire according to claim 4, since the main air chamber side portion and the sub air chamber side portion of the carcass ply overlap with each other over the entire area of the partition wall, the strength of the partition wall is very high. Therefore, even when trying to increase the internal pressure of the first auxiliary air chamber and the second auxiliary air chamber above the internal pressure of the main air chamber, the partition wall does not bend and escape to the main air chamber side due to the internal pressure difference, A desired internal pressure difference can be given to each air chamber.

  Further, in the pneumatic tire according to claim 4, since the carcass ply is continuously arranged so as to straddle each bead part in order and does not have an overlap part, a blow-out failure occurs fundamentally. In addition to being difficult, there is no peeling of the carcass in the vicinity of the base, and durability during high-speed driving is outstanding.

  The invention according to claim 5 is the pneumatic tire according to any one of claims 1 to 4, wherein in the tire axial direction, the distance between the centers of the bases of the pair of left and right partition walls is KW, When the ground contact width of the tread portion immediately below the load when the normal rim is mounted and normal internal pressure is filled in the three air chambers and the normal load is applied is TW, TW <TW.

  Here, “regular rim” refers to a standard rim in the applicable size specified in the 2004 version YEAR BOOK issued by JATMA, and “normal load” and “regular internal pressure” are similarly issued by JATMA. This refers to the maximum load and the air pressure for the maximum load in the applicable size and ply rating defined in the 2004 YEAR BOOK.

  When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  The reason for KW <TW is that when KW ≧ TW, the volume of the auxiliary air chambers on both sides of the main air chamber is relatively small compared to the main air chamber located at the center of the three air chambers. This is because when the tire is punctured by nailing or the like, the amount of deflection of the tire is absolutely increased, and the overall heat generation amount of the tire is increased, resulting in a decrease in durability.

  In the pneumatic tire according to claim 5, since KW <TW, the volume of the auxiliary air chamber can be made relatively larger than that of the main air chamber, and the main air chamber is punctured by nail-stepping or the like. However, the load can be supported by the auxiliary air chamber and the amount of deflection of the tire can be reduced. Moreover, since the heat generation of the tire is suppressed by this, the durability of the tire can be ensured.

  The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 4, wherein in the tire axial direction, the distance between the centers of the bases of the pair of left and right partition walls is KW, When the ground contact width of the tread portion immediately under the load when a normal load is loaded and a normal load is applied to each of the three air chambers and a normal load is applied, KW ≧ TW, and the outer bead portion of the base portion A pair of reinforcing layers disposed on the left and right sides of the outer carcass and the inner carcass from the side to the tread portion side are provided.

  In the pneumatic tire according to claim 6, since the reinforcing layers overlapping the outer carcass and the inner carcass are arranged from the outer bead portion side to the tread portion side of the base portion, the separation between the carcass is suppressed. In addition, even if the main air chamber is punctured due to nagging or the like under the condition of KW ≧ TW where the volume of the sub air chamber is relatively smaller than that of the main air chamber, the load is supported by the sub air chamber And the amount of deflection of the tire can be reduced.

  The invention according to claim 7 is the pneumatic tire according to any one of claims 1 to 6, wherein the inner end in the tire radial direction of the partition wall extends from the base portion of the outer bead portion in the tire width direction. It is characterized by being inside the tire radial direction from the extended virtual line.

  When the inner radial end of the partition wall (base portion of the inner bead portion) is on a virtual line extending inward in the tire width direction from the base portion of the outer bead portion, the outer side in the tire axial direction of the inner bead portion formed on the partition wall It is necessary to use a rim provided with a tall hump portion for preventing movement to the position, and the assembling work must be very difficult.

  In the pneumatic tire according to claim 7, the inner side in the tire radial direction of the partition wall (the base portion of the inner bead portion) is on the inner side in the tire radial direction from the imaginary line extending inward in the tire width direction from the base portion of the outer bead portion. Therefore, it is not necessary to use a rim provided with a tall hump as described above, and the assembly workability is good.

  As described above, according to the pneumatic tire of the present invention, in the pneumatic tire having three air chambers, it is possible to prevent the carcass from peeling off at the base portion of the partition wall and to improve the durability of the tire. Has an excellent effect.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
In FIG. 1, a pneumatic tire 100 according to the present embodiment includes an outer bead portion 12, a sidewall portion 14, a tread portion 16 connected to the sidewall portion 14, a partition wall 18, an outer carcass 21, and an inner side. The belt layer 40 is provided in the lower layer (inner side in the tire radial direction) of the tread portion 16 in the same manner as a general tire.

  A pair of outer bead portions 12 are provided on the left and right sides of the tire equatorial plane CL, and the bead cores 30 are embedded therein.

  The sidewall portions 14 are formed so as to extend outward from the pair of left and right outer bead portions 12 in the tire radial direction.

  In the tire axial direction, the center-to-center distance of each base 20 in the pair of left and right partition walls 18 is KW, and is mounted on a regular rim to be attached to three air chambers (the main air chamber 28 and the first sub air chamber 31 and the second sub air chamber on both sides thereof). It is preferable that KW <TW, where TW is the ground contact width of the tread portion 16 immediately under the load when the air chamber 32) is filled with a normal internal pressure and a normal load is applied.

  This is because, when KW ≧ TW, the volumes of the first sub-air chamber 31 and the second sub-air chamber 32 on both sides of the main air chamber 28 located at the center of the three air chambers are relative to each other. Therefore, when the main air chamber 28 is punctured by a nail pedal or the like, the amount of tire deflection becomes absolutely large, and the overall heat generation amount of the tire increases, resulting in a decrease in durability. Because it will end up.

  The partition walls 18 are provided between the pair of left and right outer bead portions 12 so as to be spaced apart from the outer bead portions 12 in the tire width direction, for example, on the left and right sides of the tire equatorial plane CL. At least one is formed to extend inward in the tire radial direction from the base portion 20 on the tire inner surface side. When the pneumatic tire 100 is attached to the rim 26 and the inner bead portion 24 provided at the inner end in the tire radial direction is brought into contact with the rim 26, the partition wall 18 is independent of the tire rim 26. Chambers (a total of three air chambers including the main air chamber 28 and the first sub air chamber 31 and the second sub air chamber 32 on both sides thereof) are formed in the tire width direction.

  The inner carcass 22 is disposed between the inner bead portions 24 formed at the inner ends in the tire radial direction of the pair of left and right partition walls 18 in a toroidal shape, and with respect to the bead core 34 disposed on the inner bead portion 24. Each end is rolled back from the inside to the outside. The inner carcass 22 may be wound around the bead core 34 from the outside to the inside.

  The outer carcass 21 on the first auxiliary air chamber 31 side is wound back from the inner side to the outer side by a bead core 30 disposed in the outer bead portion 12 on the left side of the drawing, and the first auxiliary air chamber 31 adjacent to the outer carcass 21 is provided. 1, extends to the partition wall 18 through the outer bead portion 12, the sidewall portion 14, and the base portion 20 and terminates, and overlaps with the inner carcass 22 in the partition wall 18 (in FIG. Part is represented by OL). The same applies to the outer carcass 21 on the second auxiliary air chamber 32 side.

  As illustrated, the inner carcass 22 and the left and right outer carcass 21 are disposed as separate carcass, and the inner carcass 22 and the outer carcass 21 do not overlap in the lower layer of the tread portion 16 between the pair of left and right partition walls 18. . Specifically, the inner carcass 22 and the belt layer 40 exist between the pair of left and right partition walls 18, but the outer carcass 21 does not exist. That is, the outer carcass 21 is not sandwiched between the inner carcass 22 and the belt layer 40, and the outer carcass 21 is so-called hollowed out.

  The length of the overlap part OL is, for example, 10 mm or more. The overlap portion OL takes the first sub-air chamber 31 and the first sub-chamber 31 into consideration, particularly in consideration of the internal pressure combination condition that makes the internal pressure of the first sub-air chamber 31 and the internal pressure of the second sub-air chamber 32 higher than the main air chamber pressure. 2 This is to increase the strength of the tire case around the secondary air chamber 32 so that the secondary air chamber pressure can be maintained. When the high-speed durability test was conducted using an indoor drum tester, the overlap portion It has been found that if the OL length is less than 10 mm, the amount of overlap is too small to maintain the sub-air chamber pressure, and there are many cases where blow-through failure occurs from the overlap portion OL.

  For this reason, the length of the overlap part OL needs to be 10 mm or more. More preferably, the length of the overlap portion OL is 30 mm or more.

  An inner end (inner bead portion 24) in the tire radial direction of the partition wall 18 is on the inner side in the tire radial direction from a virtual line (rim base line BLO) extending from the base portion of the outer bead portion 12 in the tire width direction. Specifically, assuming that the radius from the tire center (not shown) to the rim base line BLO of the outer bead portion 12 is RO and the radius from the tire center to the rim base line BLI of the inner bead portion 24 is RI, for example, 0 <RO -RI <50 mm.

  When the relationship between the radius RO of the outer bead portion 12 and the radius RI of the inner bead portion 24 is RO = RI, the inner bead portion 24 formed on the partition wall 18 is prevented from moving outward in the tire axial direction. A rim provided with a tall hump portion must be used, and the assembly work must be very difficult. Further, when RO-RI ≧ 50 mm, it is difficult and unrealistic to manufacture a tire using the current tire manufacturing method.

  Furthermore, when the relationship between the radius RO of the outer bead portion 12 and the radius RI of the inner bead portion 24 is RO−RI ≧ 50 mm, the radius of the inner bead portion 24 becomes too small with respect to the radius of the outer bead portion 12, Accordingly, the radius of the rim is reduced, and as a result, the diameter of the brake that can be mounted on the inner side of the rim is reduced. This is not preferable because it may cause a decrease in vehicle motion performance.

  Therefore, it is preferable to satisfy 0 <RO-RI <50 mm because it is possible to prevent inconvenience as described above.

  In the pneumatic tire 100, since the inner diameter of the inner bead portion 24 is smaller than the inner diameter of the outer bead portion 12, the rim 26 for mounting the pneumatic tire 100 is provided with the pneumatic tire 100. It is necessary to be configured so that the tire 100 can be correctly mounted.

  For this reason, the rim 26 is provided with a pair of left and right outer bead seats 26A that respectively contact the inner peripheral surfaces of the pair of left and right outer bead portions 12, and a step portion 26D on the inner side in the rim axial direction of each of the outer bead sheets 26A. A pair of left and right inner bead sheets 26B which are set to have a smaller diameter than the outer bead sheet 26A and come into contact with the inner peripheral surfaces of the pair of left and right inner bead parts 24, and one of the pair of left and right inner bead sheets 26B. A drop portion 26C provided between the other and set to have a smaller diameter than the inner bead sheet 26B is provided.

  The configuration of the rim 26 will be described in more detail. The outer bead sheet 26 </ b> A is formed according to the inner diameter of the outer bead portion 12, and the inner bead sheet 26 </ b> B is formed according to the inner diameter of the inner bead portion 24. In this example, as described above, since the inner diameter of the outer bead portion 12 is larger than the inner diameter of the inner bead portion 24, the inner bead sheet 26B is set to have a smaller diameter than the outer bead sheet 26A. Has been.

  A flange 26F that prevents the outer bead portion 12 from being pushed outward in the tire width direction is formed on the outer side in the axial direction of the outer bead sheet 26A, and is formed between the inner bead sheet 26B and the outer bead sheet 26A. Is formed with a step portion 26D that functions to prevent the inner bead portion 24 from being pushed outward in the tire width direction.

  Further, at the center in the axial direction of the rim 26, a drop portion (well) 26C in which the diameter of the groove bottom is smaller than that of the inner bead sheet 26B is provided.

  Although not shown, the rim 26 has an air valve for filling the first auxiliary air chamber 31 with gas, an air valve for filling the second auxiliary air chamber 32 with gas, and the main air chamber 28. Air valves for filling the gas are provided.

The tire / rim assembly 51 is configured by mounting the pneumatic tire 100 on the rim 26.
(Function)
In the rim 26 in the tire / rim assembly 51, the radius RO of the outer bead portion 12 is set larger than the radius RI of the inner bead portion 24, and the drop portion 26C is provided in the middle portion. When mounting 100, the outer bead portion 12 and the inner bead portion 24 can be dropped into the drop portion 26C, and the assembly of the pneumatic tire 100 to the rim 26 is performed in the same manner as the assembly of a conventional pneumatic tire. Installation is easy.

  Further, the tire width of the inner bead portion 24 is determined by the difference in diameter between the outer bead seat 26A to which the outer bead portion 12 is attached and the inner bead seat 26B to which the inner bead portion 24 is attached. Since the step portion 26D that prevents the movement outward in the direction is formed, the inner bead portion 24 is caught when the rim is assembled, and the tall hump portion that deteriorates workability is placed outside the inner bead portion 24 in the tire width direction. There is no need to form the rim, and rim assembly is facilitated.

  Further, in the tire / rim assembly 51 of the present embodiment, the first auxiliary air chamber 31, the main air chamber 28, and the second auxiliary air chamber defined by the partition wall 18 are provided between the pneumatic tire 100 and the rim 26. Since 32 is formed in the tire width direction, no other puncture occurs in any of the puncture on the ground contact surface due to the nailing of the tread portion 16 or the puncture of the sidewall portion 14 due to curb rubbing or the like 2 Since the two air chambers support the load, it is possible to continue running safely without any problems, although there is a slight decrease in tire height, a slight deterioration in steering stability, and vibration ride comfort.

  Here, the internal pressure of the first sub-air chamber 31, the internal pressure of the second sub-air chamber 32, and the internal pressure of the main air chamber 28 can be set to different arbitrary pressures. The internal pressure of the second sub-air chamber 32 and the internal pressure of the main air chamber 28 may be the same or different from each other.

  For example, if the internal pressure of the first sub air chamber 31, the internal pressure of the second sub air chamber 32, and the internal pressure of the main air chamber 28 are the same, the same characteristics as those of a conventional pneumatic tire can be obtained.

  Further, from the state in which the internal pressures of the three air chambers are set to be the same as described above, the air in the main air chamber 28 is extracted and the main air is higher than the internal pressure in the first sub air chamber 31 and the internal pressure in the second sub air chamber 32. When the internal pressure of the chamber 28 is reduced, the rigidity in the longitudinal direction of the tire is lowered and the contact area is increased, so that it is possible to improve the vibration riding comfort when traveling on rough roads and the grip performance when traveling on icy and snowy roads.

  Furthermore, if the first sub-air chamber 31 and the second sub-air chamber 32 are filled with air to increase the internal pressure, it is possible to increase the lateral rigidity and the longitudinal rigidity of the tire. Steering stability can be improved while improving ride comfort and grip performance when running on icy and snowy roads.

  In the pneumatic tire 100, KW <TW, and the outer carcass 21 and the inner carcass 22 do not overlap each other in the lower layer of the tread portion 16 between the pair of left and right partition walls. In particular, the peeling input to the overlapping portion between the inner carcass 22 and the belt layer 40 is reduced. Since progress of peeling is suppressed by this, an early failure of the tire can be prevented.

  Further, in the tire case in which the overlap portion OL forms the first auxiliary air chamber 31 and the second auxiliary air chamber 32 when the rim is mounted, the tire case around the auxiliary air chamber is located in the partition wall 18. The durability of the first sub-air chamber 31 and the second sub-air chamber 32 can be increased even when the internal pressure is higher than the internal pressure of the main air chamber 28. Can be obtained. Since the length of the overlap portion OL is secured to 10 mm or more, even if the high-speed traveling is performed under the above internal pressure combination condition, the blow-through failure does not occur from the overlap portion OL.

Also, when the main air chamber 28 is punctured due to nailing, etc., run flat with the load supported by either one or both of the first sub air chamber 31 and the second sub air chamber 32. Thus, a large peeling input is applied between the inner carcass 22 and the outer carcass 21, but even in such a severe use condition, the peeling progress of the overlapping portion between the inner carcass 22 and the belt layer 40 is suppressed, Its durability is extremely high.
[Second Embodiment]
In FIG. 2, in the pneumatic tire 200 according to the present embodiment, after the inner carcass 22 is wound back by the bead core 34, the tread portion 16 or the sidewall portion 14 extends from the partition wall 18 to the outer side in the tire axial direction through the base portion 20. The outer carcass 21 terminates before reaching the base portion 20 and overlaps with the inner carcass 22 below the side wall portion 14 and / or the tread portion 16 to form an overlap portion OL. That is, since the overlap portion OL is formed in a region closer to the outer bead portion 12 than the base portion 20, the outer carcass 21 does not overlap the belt layer 40.

  The tire / rim assembly 52 is configured by mounting the pneumatic tire 200 on the rim 26.

Since other parts are the same as those in the first embodiment, the same parts are denoted by the same reference numerals in the drawings, and description thereof is omitted.
(Function)
In the pneumatic tire 200, in the tire case in which the overlap portion OL forms the first sub air chamber 31 and the second sub air chamber 32 when the rim is mounted, in the region on the outer bead portion 12 side of the base portion 20 (for example, Since the tire case around the auxiliary air chamber is positioned, the inner pressure of the first auxiliary air chamber 31 and the inner pressure of the second auxiliary air chamber 32 can be increased. Sufficient durability that can be used even under the internal pressure combination conditions higher than the internal pressure of 28 can be obtained. Since the length of the overlap portion OL is secured to 10 mm or more, even if the high-speed traveling is performed under the above internal pressure combination condition, the blow-through failure does not occur from the overlap portion OL.

Also, when the main air chamber 28 is punctured due to nailing, etc., run flat with the load supported by either one or both of the first sub air chamber 31 and the second sub air chamber 32. Thus, a large peeling input is applied between the inner carcass 22 and the outer carcass 21, but even in such a severe use condition, the peeling progress of the overlapping portion between the inner carcass 22 and the belt layer 40 is suppressed, Its durability is extremely high.
[Third Embodiment]
In FIG. 3, in the pneumatic tire 300 according to the present embodiment, the outer carcass and the inner carcass are at least one continuous carcass ply 42. The carcass ply 42 is continuously arranged so as to straddle the left outer bead portion 12, the left inner bead portion 24, the right inner bead portion 24, and the right outer bead portion 12 in order. The end is rolled back from the inside to the outside. Therefore, in the carcass ply 42, the main air chamber side portion 42 </ b> A from the base portion 20 toward the bead core 34 and the auxiliary air chamber side portion 42 </ b> B that is rewound by the bead core 34 and returns to the base portion 20 are formed in the entire partition 18. Exists over.

  The tire / rim assembly 53 is configured by mounting the pneumatic tire 300 on the rim 26.

Since other parts are the same as those in the first embodiment, the same parts are denoted by the same reference numerals in the drawings, and description thereof is omitted.
(Function)
In the pneumatic tire 300, since the main air chamber side portion 42A and the sub air chamber side portion 42B of the carcass ply 42 overlap each other over the entire area of the partition wall 18, the strength of the partition wall 18 is very high. Therefore, even when the internal pressure of the first sub-air chamber 31 and the second sub-air chamber 32 is made higher than the internal pressure of the main air chamber 28, the partition wall 18 bends and escapes toward the main air chamber 28 due to the internal pressure difference. A desired internal pressure difference can be given to each air chamber.

Further, in the pneumatic tire 400, the carcass ply 42 is continuously disposed so as to straddle each bead portion in order, and does not have the overlap portion OL as in the first embodiment and the second embodiment. Therefore, it is difficult for a blow-out failure to occur fundamentally, and there is no peeling of the carcass in the vicinity of the base 20, so that durability during high-speed driving is outstanding.
[Fourth Embodiment]
In FIG. 4, in the pneumatic tire 400 according to the present embodiment, there is no inner carcass, and the outer bead portion 12 and the inner bead portion are surrounded by the first auxiliary air chamber 31 and the second auxiliary air chamber 32, respectively. 24, the outer carcass 21 straddles each other, and both ends of the outer carcass 21 are wound around the bead cores 30 and 34 from the inner side to the outer side as viewed from the first auxiliary air chamber 31 and the second auxiliary air chamber 32, respectively. is doing. That is, in the pneumatic tire 400, the carcass is hollowed out.

  The tire / rim assembly 54 is configured by mounting the pneumatic tire 400 on the rim 26.

Since other parts are the same as those in the first embodiment, the same parts are denoted by the same reference numerals in the drawings, and description thereof is omitted.
(Function)
In the pneumatic tire 400, the carcass is hollowed out, and the carcass does not exist on the outer side in the tire radial direction of the main air chamber 28, so that the riding comfort is excellent, and the first auxiliary air chamber 31 and the second air chamber 31 Since the periphery of the auxiliary air chamber 32 is reinforced by the outer carcass 21, even if the internal pressure of the first auxiliary air chamber 31 and the second auxiliary air chamber 32 is made higher than the internal pressure of the main air chamber 28, The partition wall 18 does not bend toward the main air chamber 28 due to the internal pressure difference and escape, and a desired internal pressure difference can be given to each air chamber.

Further, in the pneumatic tire 400, the outer carcass 21 is disposed around the first sub air chamber 31 and the second sub air chamber 32, respectively, and the overlap portion as in the first embodiment and the second embodiment. Since it does not have an OL, it is difficult to cause a blow-by failure fundamentally, and there is no peeling of the carcass near the base 20, which is excellent in durability during high-speed traveling.
[Fifth Embodiment]
In FIG. 5, the pneumatic tire 500 according to the present embodiment is such that KW ≧ TW in the pneumatic tire 100 according to the first embodiment, and further, the tread portion from the outer bead portion 12 side of the base portion 20. At least one layer of the reinforcing layers 36 is arranged in a pair on the left and right sides so as to overlap the outer sides of the outer carcass 21 and the inner carcass 22 toward the 16th side.

  Here, the reinforcing layer 36 refers to a layer that is not moored by any of the outer bead portion 12 and the inner bead portion 24 (not rewound by the bead cores 30 and 34), and is different from a so-called carcass. Therefore, although the reinforcing layer 36 extends to the tread portion 16 side with respect to the partition wall 18 and overlaps the inner carcass 22, this portion is not included in the overlap portion OL between the carcasses described above.

  The tire / rim assembly 55 is configured by mounting the pneumatic tire 500 on the rim 26.

Since other parts are the same as those in the first embodiment, the same parts are denoted by the same reference numerals in the drawings, and description thereof is omitted.
(Function)
In the pneumatic tire 500, the reinforcing layer 36 that overlaps the outer carcass 21 and the inner carcass 22 is disposed from the outer bead 12 side to the tread part 16 side of the base portion 20, so that separation between the carcass is suppressed. Can do.

Further, under the condition of KW ≧ TW, the volume of the first sub-air chamber 31 and the second sub-air chamber 32 is relatively smaller than that of the main air chamber 28. Then, although the load burden of the 1st sub-air chamber 31 and the 2nd sub-air chamber 32 becomes large, since the base 20 is reinforced with the reinforcement layer 36, at least the 1st sub-air chamber 31 or the 2nd sub-air chamber 32 is used. The load can be supported by either one of these, and the amount of deflection of the tire can be reduced. For this reason, the heat generation of the tire can be suppressed, and the durability of the tire can be sufficiently ensured.
(Test example)
Under the conditions shown in Table 1, tires according to conventional examples, comparative examples 1 and 2 and examples 1 to 5 were made as prototypes and tested for high-speed durability. The tire sizes are all 225 / 55R17.

  The evaluation of high-speed durability is based on the speed at the time of tire failure under the JIS standard high-speed performance test B condition, and is indicated by an index with the conventional example set to 100. The larger the value, the better the result. Show.

  A tire according to a conventional example (not shown) is a three-chamber tire having a pair of left and right partition walls, but unlike the present invention, KW> TW, and straddles the inner bead portion in a toroidal shape. A tire having a configuration in which an outer carcass straddling the outer bead portion in a toroidal shape is disposed on the outer side in the tire radial direction of the inner carcass, and the outer carcass is sandwiched between the belt layer located between the left and right partition walls and the inner carcass. .

  On the other hand, in FIG. 6, the pneumatic tire 600 according to the comparative example has an overlap portion OL formed by the outer carcass 21 extending and terminating to a position sandwiched between the inner carcass 22 and the belt layer 40. By attaching to the rim 26, the tire / rim assembly 56 is obtained. Comparative Example 1 is a tire having the configuration shown in FIG. 1, but the length of the overlap portion OL is less than 10 mm.

  According to this test example, both the comparative examples 1 and 2 have lower high-speed durability than the conventional example. This is considered to be because the length of the overlap portion OL is too short for Comparative Example 1, and for Comparative Example 2, the outer carcass is sandwiched between the inner carcass and the belt layer between the left and right partition walls. This is considered to be because peeling easily occurs at that portion.

  In each of the examples according to the present invention, it was confirmed that the high-speed durability was improved as compared with the conventional example.

It is sectional drawing of the cross section of the tire and rim assembly formed by mounting | wearing the rim with the pneumatic tire which concerns on 1st Embodiment. It is sectional drawing of the cross section of the tire and rim assembly formed by mounting | wearing the rim with the pneumatic tire which concerns on 2nd Embodiment. It is sectional drawing of the cross section of the tire and rim assembly formed by mounting | wearing the rim with the pneumatic tire which concerns on 3rd Embodiment. It is sectional drawing of the cross section of the tire and rim assembly formed by mounting | wearing the rim with the pneumatic tire which concerns on 4th Embodiment. It is sectional drawing of the cross section of the tire and rim assembly formed by mounting | wearing the rim with the pneumatic tire which concerns on 5th Embodiment. It is sectional drawing of the cross section of the tire and rim assembly formed by mounting | wearing the rim with the pneumatic tire which concerns on a comparative example.

Explanation of symbols

12 Outer bead part 14 Side wall part 16 Tread part 18 Bulkhead 20 Base part 21 Outer carcass 22 Inner carcass 24 Inner bead part 26 Rim 28 Main air chamber (3 air chambers)
30 Bead core 31 Vice chamber (3 chambers)
32 Secondary air chambers (3 air chambers)
34 Bead core 36 Reinforcement layer 100 Pneumatic tire 200 Pneumatic tire 300 Pneumatic tire 400 Pneumatic tire 500 Pneumatic tire BLO Rim baseline (virtual line)

Claims (7)

A pair of left and right outer bead parts with embedded bead cores;
Sidewall portions extending outward from the outer bead portion in the tire radial direction,
A tread portion connected to the sidewall portion;
The outer bead portion is provided between the pair of left and right outer bead portions so as to be spaced apart in the tire width direction, and extends inward in the tire radial direction from a base portion on the tire inner surface side in at least one of the sidewall portion and the tread portion. A pair of left and right partition walls that form an independent three air chamber in the tire width direction when the inner bead portion provided at the inner end in the tire radial direction contacts the rim and is attached to the rim. A pneumatic tire having
The pneumatic car characterized in that the outer carcass wound around the outer bead part and the inner carcass wound around the inner bead part do not overlap each other in the lower layer of the tread part between the pair of left and right partition walls. tire.   2. The air according to claim 1, wherein an overlap portion where the outer carcass and the inner carcass overlap each other is formed in the partition wall and / or in a region on the outer bead portion side from the base portion. Enter tire.   The pneumatic tire according to claim 2, wherein a length of the overlap portion is 10 mm or more.   The pneumatic tire according to claim 1, wherein the outer carcass and the inner carcass are at least one continuous carcass ply.   In the tire axial direction, the distance between the centers of the bases of the pair of left and right partition walls is KW, and is mounted on a normal rim and filled with a normal internal pressure in each of the three air chambers and loaded with a normal load. The pneumatic tire according to any one of claims 1 to 4, wherein KW <TW when the ground contact width of the tread portion is TW. In the tire axial direction, the distance between the centers of the bases of the pair of left and right partition walls is KW, and is mounted on a normal rim and filled with a normal internal pressure in each of the three air chambers and loaded with a normal load. If the ground contact width of the tread is TW, KW ≧ TW.
The left and right pairs of reinforcing layers arranged to overlap the outer side of the outer carcass and the inner carcass from the outer bead portion side to the tread portion side of the base portion, respectively. 5. The pneumatic tire according to any one of items 4.   7. The tire radial direction inner end of the partition wall is located on the tire radial direction inner side than a virtual line extending in a tire width direction from a base portion of the outer bead portion. The pneumatic tire according to item 1.

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