JP6217360B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a band-shaped sound absorbing material is bonded to a region corresponding to a tread portion on the inner surface of the tire, and more specifically, the sound absorbing material is peeled off due to bending deformation of the tread portion when the tire is removed from the wheel. The present invention relates to a pneumatic tire that can be suppressed.

  In a pneumatic tire, one of the causes for generating noise is cavity resonance sound caused by vibration of air filled in the tire. The cavity resonance sound is generated when the tread portion vibrates due to road surface irregularities when the tire rolls, and the vibration of the tread portion vibrates the air inside the tire.

  As a technique for reducing noise due to such a cavity resonance phenomenon, it has been proposed to arrange a sound absorbing material in a cavity formed between a tire and a rim of a wheel. More specifically, a band-shaped sound absorbing material is bonded to a region corresponding to the tread portion on the inner surface of the tire (see, for example, Patent Documents 1 and 2).

By the way, when removing a rim-assembled pneumatic tire from a wheel, a tire changer is generally used, but the tire changer is provided with a pressing member called a bead breaker, and the bead breaker is used to remove the bead portion of the pneumatic tire from the tire width. By pushing inward in the direction, the fitting of the bead portion to the rim is released. However, when the bead portion is pushed by the bead breaker, the tread portion is bent and deformed, so that there is a problem that the sound absorbing material adhered to the tire inner surface is easily peeled due to the bending deformation.

JP 2002-67608 A JP 2005-138760 A

  The object of the present invention is to suppress peeling of the sound absorbing material due to bending deformation of the tread portion when the tire is removed from the wheel when the band-shaped sound absorbing material is bonded to the region corresponding to the tread portion of the tire inner surface. It is to provide a pneumatic tire.

In order to solve the above-described object, the pneumatic tire of the present invention includes an annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions. And a plurality of circumferential grooves extending in the tire circumferential direction in the tread portion, and a tire circumferential direction in a region corresponding to the tread portion on the tire inner surface In the pneumatic tire in which a band-shaped sound absorbing material is bonded along an adhesive layer along a tire width direction, a first ground contact area is defined between the tire ground contact edge on one side in the tire width direction and the tire equatorial plane, When a second ground contact area is defined between the tire contact end on the other side and the tire equator plane, the center of gravity of the cross section of the plane including the tire axis of the sound absorbing material is positioned within the first ground contact area. The serial sound absorbing material disposed in a biased position in the tire width direction, the plurality of the tire equatorial plane side from the shoulder portion circumferential groove located at the outermost side in the tire width direction in the second contact region of the circumferential groove Characterized in that the other end of the sound absorbing material in the tire width direction is disposed ,
(A) the plurality of circumferential grooves include three main grooves having a width of 10 mm or more and one or two auxiliary grooves having a width of less than 10 mm;
(B) The tire flatness ratio is 55% or less, the tire ground contact width is 150 mm to 280 mm, and the tire contact direction is the maximum in the first contact region and the second contact region among the plurality of circumferential grooves. The groove width of at least one of the shoulder portion circumferential grooves located on the outside is 13 mm or more, or
(C) The ratio of the volume of the sound absorbing material to the volume of the cavity formed in the tire when the rim is assembled is greater than 20% .

  The present inventor considered the behavior of the tread portion and the sound absorbing material when the pneumatic tire in which the belt-like sound absorbing material is bonded to the region corresponding to the tread portion on the inner surface of the tire via the adhesive layer via the adhesive layer from the wheel. As a result of diligent research on the adhesion state, the tread portion is bent mainly at the shoulder portion circumferential groove located on the outermost side in the tire width direction, and when the end of the sound absorbing material is arranged at the bent portion, It has been found that the end portion is locally peeled from the inner surface of the tire, and further the peeling of the sound-absorbing material is enlarged as the tire travels, and the present invention has been achieved.

  That is, in the present invention, the sound absorbing material is disposed at a position offset in the tire width direction so that the center of gravity of the cross section of the plane including the tire axis of the sound absorbing material is located in the first ground contact region, and the sound absorbing material is arranged in the tire width direction. Since the end on the other side of the tire is disposed on the tire equatorial plane side with respect to the circumferential groove on the shoulder portion located on the outermost side in the tire width direction in the second ground contact region, the bead portion on the other side in the tire width direction is beaded. When pushed by a pressing member such as a breaker, the end portion of the sound absorbing material does not exist at the bent portion of the tread portion. Therefore, it can suppress that the edge part of a sound-absorbing material peels due to bending deformation of a tread part, and can suppress peeling as the whole sound-absorbing material by extension. As a result, the noise reduction effect based on the sound absorbing material can be maintained over a long period of time.

  Here, it is conceivable that the end of the sound absorbing material is not disposed in the vicinity of the shoulder portion circumferential groove by simply reducing the width of the sound absorbing material. However, in this case, a sufficient noise reduction effect cannot be obtained by reducing the width of the sound absorbing material. In contrast, in the present invention, the sound absorbing material is disposed at a position offset in the tire width direction so that the center of gravity of the cross section of the plane including the tire axis of the sound absorbing material is located in the first ground contact region. The other end of the material in the tire width direction is disposed closer to the tire equator than the shoulder circumferential groove in the second ground contact region, and at the same time, the width of the sound absorbing material can be sufficiently secured.

  In the present invention, the tire ground contact edge is an end portion in the tire axial direction of the ground contact area formed when a normal load is applied by placing the tire on a regular rim and filling the regular internal pressure vertically on a plane. The tire ground contact width is a width in the tire axial direction of the ground contact region. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO. Then, “Measuring Rim” is set. However, when the tire is a tire mounted on a new vehicle, the volume of the cavity is determined using a genuine wheel in which the tire is assembled. “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum air pressure is JATMA, and the table “TIRE ROAD LIMITS AT VARIOUS” is TRA. The maximum value described in “COLD INFRATION PRESURES”, “INFLATION PRESURE” if it is ETRTO, but if the tire is a new car mounted tire, the air pressure displayed on the vehicle is used. “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is JATMA, and the table “TIRE ROAD LIMITS AT VARIOUS” is TRA. The maximum value described in “COLD INFORATION PRESSURES” is “LOAD CAPACITY” if it is ETRTO, but if the tire is a passenger car, the load is equivalent to 88% of the load. When the tire is a tire mounted on a new vehicle, the wheel load obtained by dividing the longitudinal axle weight described in the vehicle verification of the vehicle by 2, respectively.

  A circumferential groove is a groove extending in the tire circumferential direction, but a groove having a width of 1.8 mm or less does not substantially affect the bending deformation of the tread portion. It shall be excluded from the circumferential groove. The width of the circumferential groove is a groove width at the tread surface of the tread portion measured in a state where the tire is assembled on a normal rim and filled with a normal internal pressure.

  In the present invention, it is preferable to display on the outer surface of the tire the mounting orientation in which the center of gravity of the sound absorbing material is disposed on the inner side of the wheel from the tire equator when the rim is assembled. That is, when the tire is removed from the wheel using the tire changer, the tread portion is greatly deformed at the outer portion of the wheel. By adopting a configuration in which the rim is arranged on the inner side of the wheel than the tire equator surface, the effect of suppressing the peeling of the sound absorbing material can be enhanced.

  Further, in the present invention, the cross-sectional areas of the shoulder portion circumferential grooves located on the outermost sides in the tire width direction in the first ground contact region and the second ground contact region among the plurality of circumferential grooves are made different from each other. The cross-sectional area of the shoulder portion circumferential groove in the region is preferably smaller than the cross-sectional area of the shoulder portion circumferential groove in the second grounding region. That is, it is preferable to arrange the shoulder portion circumferential groove having the smaller cross-sectional area and the area center of gravity of the sound absorbing material on the same side (first contact region) with respect to the tire equator plane. Since the bending deformation of the tread part is suppressed as the cross-sectional area of the shoulder part circumferential groove is small, the above arrangement prevents the end part on one side in the tire width direction of the sound absorbing material from peeling off, and the sound absorbing material is peeled off. The suppression effect can be enhanced.

  The sound absorbing material is preferably disposed between the tire ground contact edge on one side in the tire width direction and the tire ground contact edge on the other side in the tire width direction. Since the curvature of the inner surface of the tire is larger outside the tire ground contact end, it is difficult for the end of the sound absorbing material to peel off by accommodating the sound absorbing material within the above range.

  It is preferable to arrange each end of the sound absorbing material in a region immediately below the land portion defined by the circumferential groove. Thus, by excluding each end of the sound absorbing material from the region directly below the circumferential groove, the end of the sound absorbing material becomes difficult to peel off.

  The plurality of circumferential grooves preferably include three main grooves having a width of 10 mm or more and one or two auxiliary grooves having a width of less than 10 mm. In this case, the necessary tire performance can be ensured based on the plurality of circumferential grooves including the main groove and the auxiliary groove while ensuring the degree of freedom in selecting the attachment position of the sound absorbing material.

  The tire flatness ratio is 55% or less, the tire contact width is 150 mm to 280 mm, and each of the plurality of circumferential grooves is located on the outermost side in the tire width direction in the first contact area and the second contact area. It is preferable that the width of at least one of the shoulder portion circumferential grooves is 13 mm or more. Since the pneumatic tire having such characteristics tends to bend and deform at the tread portion when it is removed from the wheel, it is important to suppress peeling of the sound absorbing material.

  The sound-absorbing material is a single sound-absorbing material extending in the tire circumferential direction, and has a uniform thickness at least in a range corresponding to the adhesive surface in a cross section orthogonal to the longitudinal direction, and the cross-sectional shape thereof extends along the longitudinal direction. And constant. Thereby, the capacity | capacitance of the sound-absorbing material per adhesion area can be maximized, and the outstanding noise reduction effect can be acquired. Moreover, since the sound absorbing material having such a shape is easy to process, the manufacturing cost is also low.

  The ratio of the volume of the sound absorbing material to the volume of the cavity formed in the tire when the rim is assembled is preferably larger than 20%. Thus, by increasing the volume of the sound absorbing material, an excellent noise reduction effect can be obtained, and even in the case of a large sound absorbing material, a good adhesion state can be ensured over a long period of time. The volume of the cavity is the volume of the cavity formed between the tire and the rim in a state where the tire is assembled on the regular rim and filled with the regular internal pressure.

  The sound absorbing material has a hardness of 60N to 170N, and the sound absorbing material preferably has a tensile strength of 60 kPa to 180 kPa or more. The sound absorbing material having such physical properties is excellent in durability against shear strain. The hardness of the sound absorbing material is measured in accordance with JIS-K6400-2 “Soft foam material—physical characteristics—Part 2: Determination of hardness and compressive stress—strain characteristics”. It is measured by the method (a method for obtaining a force after 20 seconds after a constant compression of 25%). The tensile strength of the sound absorbing material is measured in accordance with JIS-K6400-5 “Soft foam material—physical properties—Part 5: Determination of tensile strength, elongation and tear strength”.

  The adhesive layer is composed of a double-sided adhesive tape, and the peel adhesive strength thereof is preferably in the range of 8 N / 20 mm to 40 N / 20 mm. As a result, it is possible to easily perform the attaching operation of the sound absorbing material and the dismantling operation at the time of discarding the tire while keeping the fixing strength of the sound absorbing material good. The peel adhesive strength of the double-sided adhesive tape is measured according to JIS-Z0237. That is, the double-sided PSA sheet is lined with a 25 μm thick PET film. The backed adhesive sheet is cut into a 20 mm × 200 mm square to produce a test piece. The release liner is peeled from the test piece, and the exposed adhesive surface is attached to a stainless steel (SUS304, surface finish BA) plate as an adherend by reciprocating a 2 kg roller. After maintaining this in an environment of 23 ° C. and 50% RH for 30 minutes, using a tensile tester, in accordance with JIS Z 0237, in an environment of 23 ° C. and RH 50%, a peeling angle of 180 ° and a tensile speed of 300 mm / min. Under the conditions described above, the 180 ° peeling adhesion to the SUS plate is measured.

1 is a perspective sectional view showing a pneumatic tire according to an embodiment of the present invention. 1 is an equatorial line cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. It is an expanded view which shows the tread pattern of the pneumatic tire which consists of embodiment of this invention. It is meridian sectional drawing which shows a state when the pneumatic tire which consists of embodiment of this invention is removed from a wheel. It is meridian sectional drawing which shows the pneumatic tire which consists of other embodiment of this invention. It is meridian sectional drawing which shows the pneumatic tire which consists of other embodiment of this invention. It is meridian sectional drawing which shows the pneumatic tire which consists of other embodiment of this invention. It is sectional drawing which expands and shows the circumferential groove | channel in the pneumatic tire of this invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 5 show a pneumatic tire according to an embodiment of the present invention. 1 to 3, the pneumatic tire of the present embodiment includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions 2 that are disposed on both sides of the tread portion 1. A pair of bead portions 3 are provided inside the sidewall portions 2 in the tire radial direction.

  As shown in FIG. 4, four circumferential grooves 21 (21 a, 21 b, 21 c, 21 d) that extend in the tire circumferential direction are formed in the tread portion 1, and five rows of land portions 22 are formed by these circumferential grooves 21. Is partitioned. Further, a lug groove 23, an inclined groove 24, and a notch groove 25 extending in the tire width direction are formed in the land portions 22.

  In the pneumatic tire, a band-shaped sound absorbing material 6 is bonded to a region corresponding to the tread portion 1 of the tire inner surface 4 via an adhesive layer 5 along the tire circumferential direction. The sound absorbing material 6 is made of a porous material having open cells, and has predetermined sound absorbing characteristics based on the porous structure. As the porous material of the sound absorbing material 6, foamed polyurethane may be used. On the other hand, as the adhesive layer 5, a paste adhesive or a double-sided adhesive tape can be used.

  As shown in FIG. 3, a first ground contact area A1 is defined between the tire ground contact edge E1 on one side in the tire width direction (left side in FIG. 3) and the tire equatorial plane E0, and the other side in the tire width direction (FIG. 3). 3), when the second ground contact area A2 is defined between the tire ground contact edge E2 and the tire equatorial plane E0, the area center of gravity G of the cross section (meridian cross section) by the plane including the tire axis of the sound absorbing material 6 is the first. The sound absorbing material 6 is arranged at a position deviated in the tire width direction so as to be located in the ground contact area A1. And the edge part 61 of the one side of the tire width direction of the sound-absorbing material 6 is arrange | positioned in the tire width direction outer side rather than the shoulder part circumferential groove | channel 21a located in the outermost side of a tire width direction in 1st grounding area | region A1. On the other hand, the end 62 on the other side in the tire width direction of the sound absorbing material 6 is disposed closer to the tire equatorial plane E0 than the shoulder portion circumferential groove 21d located on the outermost side in the tire width direction in the second ground contact area A2. ing. The tread portion 1 is provided with a single sound absorbing material 6 in the tire meridian cross section, and the plurality of sound absorbing materials 6 are not arranged in the tire width direction.

  When removing the pneumatic tire constituted in this way from the rim R of the wheel, as shown in FIG. 5, the bead portion 3 of the pneumatic tire is moved to the inner side in the tire width direction by a pressing member such as a bead breaker. , The fitting of the bead portion 3 to the rim R is released. At that time, the tread portion 1 is bent and deformed particularly at the shoulder portion circumferential groove 21d.

  However, the pneumatic tire includes a tire shaft of the sound absorbing material 6 when the band-shaped sound absorbing material 6 is bonded to the region corresponding to the tread portion 1 of the tire inner surface 4 via the adhesive layer 5 along the tire circumferential direction. The sound absorbing material 6 is arranged at a position offset in the tire width direction so that the center of gravity G of the cross section of the plane is located in the first ground contact region A1, and the end 62 on the other side of the sound absorbing material 6 in the tire width direction is the first. 2 Since the tire equator plane E0 side is disposed on the tire equator plane E0 side than the shoulder portion circumferential groove 21d located on the outermost side in the tire width direction in the ground contact area A2, the bead portion 3 on the other side in the tire width direction is pressed by a bead breaker or the like. The end portion 62 of the sound absorbing material 6 does not exist in the bent portion of the tread portion 1 when pushed by the member. Therefore, it can suppress that the edge part 62 of the sound-absorbing material 6 peels resulting from the bending deformation of the tread part 1, and can suppress the peeling of the sound-absorbing material 6 as a whole. As a result, the noise reduction effect based on the sound absorbing material 6 can be maintained over a long period of time.

  Further, in the pneumatic tire, the sound absorbing material 6 is not trapped by the symmetrical arrangement of the sound absorbing material 6 so that the center of gravity G of the cross section of the plane including the tire axis of the sound absorbing material 6 is located in the first ground contact area A1. Is disposed at a position offset in the tire width direction, the end 62 on the other side of the sound absorbing material 6 in the tire width direction is closer to the tire equatorial plane E0 than the shoulder circumferential groove 21d of the second ground contact area A2. A sufficient width of the sound absorbing material 6 can be secured simultaneously with the placement. Therefore, a good noise reduction effect can be obtained based on the wide sound absorbing material 6.

  FIG. 6 shows a pneumatic tire according to another embodiment of the present invention. In FIG. 3, the sound absorbing material 6 is disposed so as to straddle both sides of the tire equatorial plane E0. However, in FIG. 6, the sound absorbing material 6 is disposed only on one side of the tire equatorial plane E0. That is, the sound absorbing material 6 is stored in the first ground contact area A1. Such a sound absorbing material 6 can be arranged, but in this case, it is difficult to ensure a sufficient width of the sound absorbing material 6.

  FIG. 7 shows a pneumatic tire according to another embodiment of the present invention. This pneumatic tire has a designated mounting direction with respect to the vehicle, IN is an inner side when the vehicle is mounted (that is, the inside of the wheel), and OUT is an outer side when the vehicle is mounted (that is, the outside of the wheel). As shown in FIG. 7, in the pneumatic tire, a display portion 8 that displays the mounting direction is formed on the tire outer surface of the sidewall portion 2. For example, “outside” is displayed on the display unit 8 disposed on the side wall 2 that is outside when the vehicle is mounted. When the pneumatic tire is assembled on the rim based on the mounting direction displayed on the display unit 8, the area gravity center G of the sound absorbing material 6 is arranged on the wheel inner side (IN) than the tire equatorial plane E0. Yes. When the tire is removed from the wheel using the tire changer, the tread portion 1 is largely deformed on the outer side (OUT) of the wheel. Therefore, in the pneumatic tire in which the mounting direction with respect to the vehicle is specified, the area of the sound absorbing material 6 By adopting a configuration in which the center of gravity G is arranged on the wheel inner side (IN) than the tire equatorial plane E0 when the rim is assembled, peeling of the sound absorbing material 6 can be effectively suppressed.

  FIG. 8 shows a pneumatic tire according to another embodiment of the present invention. In FIG. 8, the cross-sectional areas of the shoulder circumferential grooves 21a and 21d located on the outermost sides in the tire width direction in the first ground contact area A1 and the second ground contact area A2 among the plurality of circumferential grooves 21 are different from each other. The cross-sectional area of the shoulder portion circumferential groove 21a in the first grounding area A is made smaller than the cross-sectional area of the shoulder portion circumferential groove 21d in the second grounding area A2. That is, the shoulder portion circumferential groove 21a having the smaller cross-sectional area and the area gravity center G of the sound absorbing material 6 are arranged in the first ground contact area A1 on the same side with respect to the tire equator plane E0. Since the bending deformation of the tread portion 1 is suppressed as the cross-sectional areas of the shoulder portion circumferential grooves 21a and 21d are smaller, the end portion 61 on one side of the sound absorbing material 6 in the tire width direction is peeled off by such an arrangement. The effect of suppressing and suppressing peeling of the sound absorbing material 6 can be enhanced.

  In the pneumatic tire of each of the embodiments described above, the sound absorbing material 6 is preferably disposed between the tire ground contact end E1 on one side in the tire width direction and the tire ground contact end E2 on the other side in the tire width direction. Since the inner surface 4 of the tire has a larger curvature outside the tire ground contact ends E1 and E2, the sound absorbing material 6 is accommodated within a range defined between the tire contact end E1 on one side and the tire contact end E2 on the other side. This makes it difficult for the end portions 61 and 62 of the sound absorbing material 6 to peel off.

  In the pneumatic tire according to each of the embodiments described above, it is preferable that the end portions 61 and 62 of the sound absorbing material 6 are arranged in a region directly below the land portion 22 defined by the circumferential groove 21. As described above, by removing the end portions 61 and 62 of the sound absorbing material 6 from the region directly below the circumferential groove 21, the end portions 61 and 62 of the sound absorbing material 6 are difficult to peel off.

  Further, as shown in FIG. 8, the plurality of circumferential grooves 21 include three main grooves (21b, 21c, 21d) having a width of 10 mm or more and one or two auxiliary grooves (21a) having a width of less than 10 mm. ) Is preferably included. In this case, necessary tire performance can be ensured based on the plurality of circumferential grooves 21 including the main grooves and the auxiliary grooves, while ensuring the degree of freedom in selecting the position where the sound absorbing material 6 is attached.

  Furthermore, in the pneumatic tire of each embodiment described above, the tire flatness ratio is 55% or less, the tire ground contact width is 150 mm to 280 mm, and the first ground contact region A1 and the second ground contact region among the plurality of circumferential grooves 21. It is preferable that at least one of the shoulder portion circumferential grooves 21a and 21d positioned on the outermost side in the tire width direction in the contact area A2 is 13 mm or more. A pneumatic tire having such characteristics tends to be bent and deformed greatly when the tread portion 1 is removed from the wheel. Therefore, suppressing the peeling of the sound absorbing material 6 based on the arrangement structure of the sound absorbing material 6 is significant in the pneumatic tire as described above.

  As shown in FIG. 9, the width Gw of the circumferential groove 21 is the groove width on the tread surface of the tread portion 1, but when the circumferential groove 21 has a chamfered portion, the circumferential groove 21 in the tire meridian cross section. The width Gw is measured with reference to a virtual point where the extension line of the groove wall and the extension line of the tread intersect. When the width Gw of the circumferential groove 21 changes along the tire circumferential direction, the average value is used.

  In the pneumatic tire, a single sound absorbing material 6 extends in the tire circumferential direction, and the sound absorbing material 6 has a uniform thickness in a range corresponding to at least an adhesive surface in a cross section perpendicular to the longitudinal direction. The cross-sectional shape is preferably constant along the longitudinal direction. In particular, the cross-sectional shape of the cross section orthogonal to the longitudinal direction of the sound absorbing material 6 is preferably a rectangle (including a square), but depending on the case, it may be an inverted trapezoid so that the bonding surface side becomes narrow. . Thereby, the capacity | capacitance of the sound-absorbing material 6 per adhesion area can be maximized, and an excellent noise reduction effect can be obtained. Further, since the sound absorbing material 6 having such a shape is easy to process, the manufacturing cost is also low.

  When the rim of the pneumatic tire is assembled, a cavity 7 is formed between the tire inner surface 4 and the rim, and the volume ratio of the sound absorbing material 6 to the volume of the cavity 7 is larger than 20%. preferable. Thus, by increasing the volume of the sound absorbing material 6, an excellent noise reduction effect can be obtained, and even in the case of the large sound absorbing material 6, a good adhesion state can be secured for a long period of time. The width of the sound absorbing material 6 is preferably in the range of 30% to 90% of the tire ground contact width. The sound absorbing material 6 is preferably non-annular.

  The sound absorbing material 6 has a hardness (JIS-K6400-2) of 60N to 170N, and the sound absorbing material 6 preferably has a tensile strength (JIS-K6400-5) of 60 kPa to 180 kPa. The sound absorbing material 6 having such physical properties has excellent durability against shear strain. If the hardness or tensile strength of the sound absorbing material 6 is too small, the durability of the sound absorbing material 6 will be reduced. In particular, the hardness of the sound absorbing material 6 is preferably 70N to 160N, and more preferably 80N to 140N. The tensile strength of the sound absorbing material 6 is preferably 75 kPa to 165 kPa, more preferably 90 kPa to 150 kPa.

  The adhesive layer 5 preferably has a peel adhesive strength (JIS-Z0237: 2009) in the range of 8 N / 20 mm to 40 N / 20 mm. Thereby, it is possible to easily perform the attaching operation of the sound absorbing material 6 and the dismantling operation at the time of discarding the tire while keeping the fixing strength of the sound absorbing material 6 good. That is, if the peeling force of the adhesive layer 5 is too weak, the fixed state of the sound absorbing material 6 becomes unstable. Conversely, if the peeling force of the adhesive layer 5 is too strong, the attaching position is changed in the attaching operation of the sound absorbing material 6. It becomes difficult to peel off the sound absorbing material 6 when the tire is discarded. In particular, the peel adhesive strength of the adhesive layer 5 is preferably 9 N / 20 mm to 30 N / 20 mm, more preferably 10 N / 20 mm to 25 N / 20 mm.

  The tire size is 275 / 35R20 and extends in the tire circumferential direction to form an annular tread portion, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions disposed on the inner side in the tire radial direction. And a plurality of circumferential grooves extending in the tire circumferential direction in the tread portion, and a belt-like shape is formed in the region corresponding to the tread portion on the inner surface of the tire via an adhesive layer along the tire circumferential direction. In the pneumatic tire to which the sound absorbing material was bonded, tires of Comparative Example 1 and Examples 1 to 3 having different arrangements of the sound absorbing material were manufactured.

  In Comparative Example 1, the sound absorbing material was disposed symmetrically with respect to the tire equatorial plane, and as a result, both end portions of the sound absorbing material were respectively disposed immediately below the shoulder portion circumferential grooves.

  In Example 1, as shown in FIG. 3, the sound absorbing material is disposed at a position offset in the tire width direction so that the center of gravity of the cross section of the plane including the tire axis of the sound absorbing material is located in the first ground contact region. The other end of the sound absorbing material in the tire width direction is disposed on the tire equatorial plane side with respect to the shoulder circumferential groove located on the outermost side in the tire width direction in the second ground contact region. As the circumferential main grooves, four main grooves (width 13 mm) were arranged.

  In Example 2, as shown in FIG. 6, the sound absorbing material is disposed at a position offset in the tire width direction so that the center of gravity of the cross section of the plane including the tire axis of the sound absorbing material is located in the first ground contact region. The other end of the sound absorbing material in the tire width direction is disposed on the tire equatorial plane side with respect to the shoulder circumferential groove located on the outermost side in the tire width direction in the second ground contact region. As the circumferential main grooves, four main grooves (width 13 mm) were arranged.

  In Example 3, as shown in FIG. 8, the sound absorbing material is disposed at a position offset in the tire width direction so that the center of gravity of the cross section of the plane including the tire axis of the sound absorbing material is located in the first ground contact region. The other end of the sound absorbing material in the tire width direction is disposed on the tire equatorial plane side with respect to the shoulder circumferential groove located on the outermost side in the tire width direction in the second ground contact region. As the circumferential main groove, three main grooves (width 13 mm) and one auxiliary groove (width 5 mm) were arranged.

  In Comparative Example 1 and Examples 1 to 3, the following matters were made common. The tire ground contact width is 205 mm. The cross-sectional shape in the cross section orthogonal to the longitudinal direction of the sound absorbing material was a rectangle, and the cross-sectional shape was constant along the tire circumferential direction. The ratio of the volume of the sound absorbing material to the volume of the cavity formed in the tire when assembling the rim was 30%. The sound absorbing material had a hardness of 91 N and the sound absorbing material had a tensile strength of 132 kPa. The adhesive strength for peeling off the adhesive layer was 16 N / 20 mm.

  The pneumatic tires of Comparative Example 1 and Examples 1 to 3 were each assembled to a wheel having a rim size of 20 × 9.5 J, and the tire and the wheel were desorbed twice using a tire changer, and then the air pressure was 150 kPa, the load After running a running test for 100 hours with a drum tester under conditions of 6.9 kN and speed of 150 km / h, the presence or absence of adhesion peeling of the sound absorbing material was visually confirmed. The results are shown in Table 1.

  As shown in Table 1, the sound absorbing material peeled off significantly in the tire of Comparative Example 1, but in the tires of Examples 1 to 3, no sound absorbing material peeled off.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Bead part 3 Side wall part 4 Tire inner surface 5 Adhesive layer 6 Sound absorbing material 7 Cavity part 8 Display part 21 Circumferential groove E0 Tire equatorial plane E1 One side tire ground end E2 The other side tire ground end A1 1st Grounding area A2 Second grounding area G Area center of gravity

Claims (10)

An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. A plurality of circumferential grooves extending in the tire circumferential direction are provided in the tread portion, and a band-shaped sound absorbing material is bonded to a region corresponding to the tread portion on the tire inner surface via an adhesive layer along the tire circumferential direction. In the pneumatic tire, a first contact area is defined between a tire contact end on one side in the tire width direction and the tire equator plane, and a first contact area is defined between the tire contact end on the other side in the tire width direction and the tire equator plane. 2 when defining a contact region, said sound absorbing material so that the area centroid of the cross section with respect to the plane containing the tire axis of said sound absorbing material is located on the first ground region disposed on the biased position of the tire width direction, wherein Placing an end portion of the other side in the tire width direction of the noise absorbing member to the tire equatorial plane side from the shoulder portion circumferential groove located at the outermost side in the tire width direction in the second ground area of several circumferential grooves And the plurality of circumferential grooves include three main grooves having a width of 10 mm or more and one or two auxiliary grooves having a width of less than 10 mm . An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. A plurality of circumferential grooves extending in the tire circumferential direction are provided in the tread portion, and a band-shaped sound absorbing material is bonded to a region corresponding to the tread portion on the tire inner surface via an adhesive layer along the tire circumferential direction. In the pneumatic tire, a first contact area is defined between a tire contact end on one side in the tire width direction and the tire equator plane, and a first contact area is defined between the tire contact end on the other side in the tire width direction and the tire equator plane. When the two ground contact areas are defined, the sound absorbing material is disposed at a position offset in the tire width direction so that the center of gravity of the cross section of the plane including the tire axis of the sound absorbing material is located in the first ground contact area, Among the several circumferential grooves, the other end of the sound absorbing material in the tire width direction is disposed on the tire equatorial plane side than the shoulder circumferential groove located on the outermost side in the tire width direction in the second ground contact region. And the tire flatness ratio is 55% or less, the tire contact width is 150 mm to 280 mm, and the tire contact width direction is the highest in the first contact area and the second contact area among the plurality of circumferential grooves. A pneumatic tire characterized in that at least one groove width of a circumferential circumferential groove located on the outer side is 13 mm or more. An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. A plurality of circumferential grooves extending in the tire circumferential direction are provided in the tread portion, and a band-shaped sound absorbing material is bonded to a region corresponding to the tread portion on the tire inner surface via an adhesive layer along the tire circumferential direction. In the pneumatic tire, a first contact area is defined between a tire contact end on one side in the tire width direction and the tire equator plane, and a first contact area is defined between the tire contact end on the other side in the tire width direction and the tire equator plane. When the two ground contact areas are defined, the sound absorbing material is disposed at a position offset in the tire width direction so that the center of gravity of the cross section of the plane including the tire axis of the sound absorbing material is located in the first ground contact area, Among the several circumferential grooves, the other end of the sound absorbing material in the tire width direction is disposed on the tire equatorial plane side than the shoulder circumferential groove located on the outermost side in the tire width direction in the second ground contact region. a pneumatic tire and, and the ratio of the volume of the sound absorbing material to the volume of the cavity formed in the tire at a rim assembly being greater than 20%. The pneumatic tire according to any one of claims 1 to 3, wherein a mounting direction in which the center of gravity of the sound absorbing material is disposed on the inner side of the wheel from the tire equator when the rim is assembled is displayed on the outer surface of the tire. Among the plurality of circumferential grooves, the cross-sectional areas of the shoulder circumferential grooves located on the outermost sides in the tire width direction in the first ground region and the second ground region are different from each other, and the first ground region The pneumatic tire according to any one of claims 1 to 3, wherein a cross-sectional area of the shoulder portion circumferential groove is smaller than a cross-sectional area of the shoulder portion circumferential groove of the second ground contact region. The pneumatic tire according to any one of claims 1 to 5, characterized in that said sound absorbing material is arranged between said one tire ground contact edge side and the other side of the tire ground contact end. The pneumatic tire according to any one of claims 1 to 6 , wherein each end portion of the sound absorbing material is arranged in a region immediately below a land portion partitioned by a circumferential groove.   The sound-absorbing material is a single sound-absorbing material extending in the tire circumferential direction, and has a uniform thickness at least in a range corresponding to the adhesive surface in a cross section perpendicular to the longitudinal direction, and the cross-sectional shape thereof is in the longitudinal direction. The pneumatic tire according to any one of claims 1 to 7, wherein the pneumatic tire is constant along the tire. The pneumatic tire according to any one of claims 1 to 8 , wherein the sound absorbing material has a hardness of 60 N to 170 N, and the sound absorbing material has a tensile strength of 60 kPa to 180 kPa. The pneumatic tire according to any one of claims 1 to 9 , wherein the adhesive layer is made of a double-sided adhesive tape, and the peel adhesive strength thereof is in the range of 8N / 20mm to 40N / 20mm.

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