JP5973694B2 - Pneumatic tire - Google Patents

Description

  In the tread circumferential direction, the belt reinforcing layer made of twisted cords, bundle filaments, monofilaments, or other reinforcing elements extending in the form of a straight line, a zigzag, or the like is overlapped on the outer peripheral side of the belt reinforcing layer. This invention relates to pneumatic tires suitable for use as heavy duty vehicle tires for trucks, buses, etc., industrial vehicle tires, construction vehicle tires, etc., provided with the arranged belt in the tread part. The present invention proposes a technique for preventing the occurrence of interlayer separation between the side edge of the layer or the vicinity thereof with the belt.

  This conventional belt comprising a belt reinforcing layer composed of reinforcing elements extending in the tread circumferential direction and a belt composed of two or more layers of belt layers in which the cords cross each other and are arranged on the outer peripheral side of the belt reinforcing layer. Examples of such tires include those described in Patent Documents 1 and 2.

JP-A-2-208101 International Publication No. 2008/102667 Pamphlet

  By the way, when each belt reinforcement layer described in Patent Documents 1 and 2 is formed by a spiral wound structure of a ribbon-like strip formed by rubber-covering one or a plurality of reinforcing elements. For example, when a ribbon-like strip having a width of 3 to 20 mm is spirally wound from a position serving as one side edge of the belt reinforcing layer having a required width toward a position serving as the other side edge. The cut end of the reinforcing element is present at each of the winding start end and winding end of the strip, and the position corresponding to each of the winding start end and winding end corresponds to the belt reinforcing layer and the belt. When the belt reinforcement layer is arranged in two layers in order to ensure the required strength under the same winding condition of the ribbon-like strip, As a necessary consequence of spirally winding a strip of a width, there is a portion where a belt reinforcing layer is formed at each of the winding start end and winding end of the strip. In order to solve this problem, if the double layer stack of the strip is ensured at each of the spiral winding start end and the spiral winding end of the strip, this time, the winding start end and winding A portion where the strip overlaps three layers is generated at each end, and a belt cord crossing region of a belt composed of two or more belt layers where cords cross each other is formed on the outer peripheral side of the three layer overlapping portion. When laminated, the thickness of the interlayer rubber, such as the coated rubber layer, between the belt reinforcement layer and the belt at the three-layer overlapping part of the strip is due to the flow of the interlayer rubber during raw tire vulcanization molding, etc. And thin Therefore, separation between them were other problems that tend to occur by a circumferential shear deformation of the belt reinforcing layer and the belt.

  The problem is that the winding mode of the ribbon-shaped strip having a width of 3 to 20 mm is changed, for example, the winding start end of the strip is positioned in the center of the tread, and the strip is moved from the center of the tread to the belt having the required width. After spirally winding up to a position that becomes one side edge of the reinforcing layer, after winding the strip in two layers at that side edge position, to the position that becomes the other side edge of the belt reinforcing layer of the required width The strip is spirally wound, and the strip is laminated and wound in two layers at the other side edge position, and then the strip is spirally wound up to a position before the winding start end. The same applies to the case where the belt reinforcing layer is formed. This also causes a region where the strips overlap in three layers at each side edge portion of the formed belt reinforcing layer. Up Separation such as that there is a problem that tends to occur.

  An object of the present invention is to solve such problems of the prior art, and the object of the present invention is to provide two or more belt reinforcing layers in the form of ribbons. When forming with a spiral wound structure of a stop, it is inevitable that an increased area of the number of winding layers is generated at each side edge portion of the belt reinforcing layer having a required width. Providing a pneumatic radial tire that can effectively prevent the occurrence of interlayer separation between the belt reinforcement layer and the belt consisting of two or more belt layers where the cords cross each other even when the increased area occurs There is.

The pneumatic radial tire of the present invention is in the form of a linear shape, a zigzag shape, etc., outside the crown area of the toroidal carcass with the side portion wound around the bead core, inside the tread rubber, in the tread circumferential direction. Two layers of belt reinforcement layer consisting of reinforcing elements made of metallic or organic twisted cords, bundle filaments, monofilaments, etc. and belt layer cords, for example, are opposite to each other with respect to the tire equatorial plane A belt composed of two or more belt layers extending in the direction and intersecting each other is sequentially arranged from the inner side to the outer side in the tire radial direction. tire radial reinforcing elements of the or a plurality of strips formed by subjecting a rubber coating between the strip adjacent in the tire width direction in at least a portion of the belt reinforcing layer Formed by helically wound structure configured in a state of being wound in a spiral shape so as not to overlap the counter, at least partially form a region to become a three-layer structure on each side of the belt reinforcing layer, When the width of the strip of the belt reinforcing layer is A,
Maximum crossing width of belt layer cord of belt <(belt reinforcing layer-2A)
In addition, the width center position of the maximum crossing width of the belt layer cord is positioned corresponding to the width center position of the belt reinforcing layer in the tire radial direction.

Therefore, here, the one or more belt layers in which the belt cords do not cross each other can have the same width as the belt reinforcing layer or a width exceeding the same.
Further, here, when the reinforcing element has a zigzag-shaped detoured extended form, the destructive form may be lost in a state in which the rim-assembled tire is filled with the air pressure defined by the standard. It is preferable for the belt reinforcing layer made of to sufficiently exhibit the diameter growth suppressing function.

The present invention provides a belt reinforcing layer formed by spirally winding a ribbon-like strip. For example, when the belt reinforcing layer has a two-layer laminated structure as described above, the belt reinforcing layer It was made by paying attention to the fact that even if a partial region having a three-layer structure is generated on each side of the layer, the width of the region does not exceed the width of the spirally wound strip. In the pneumatic tire of the present invention, a belt lamination mode with respect to a belt reinforcing layer that becomes a spiral wound structure of a ribbon-like strip,
The width of the belt reinforcing layer strip is A,
Maximum crossing width of belt layer cord of belt <(belt reinforcement width-2A)
In addition, the belt center cord crossing area of the belt layer cord can be obtained by positioning the width center position of the maximum crossing width of the belt layer cord corresponding to the center position of the width of the belt reinforcing layer in the tire radial direction. Are located apart from each side edge of the belt reinforcing layer by a distance larger than the width A of the belt reinforcing layer strip, so that the belt layer cord crossing region of the belt has a three-layer structure of the belt reinforcing layer. Positioning on the outer peripheral side of the partial region can be sufficiently prevented.

  Therefore, even if the belt is disposed on a part of the belt reinforcing layer having, for example, a three-layer structure, the belt is strengthened by heating and pressurizing during vulcanization molding of the raw tire. For example, one belt layer on the outer peripheral side of the three-layer structure region of the layer can be easily escaped and deformed radially outward in a direction away from the belt reinforcing layer. It is possible to effectively suppress the flow of the interlayer rubber such as the cord-covered rubber layer between the belt and the belt, thereby effectively preventing the thickness of the interlayer rubber from being reduced.

  As a result, in the product tire, even when a relative shear deformation in the circumferential direction occurs between the belt reinforcing layer and the belt, the relative deformation can be effectively absorbed under a sufficient interlayer rubber thickness. Therefore, the occurrence of separation between the belt reinforcing layer and the belt can be effectively prevented.

  On the other hand, the belt layer cord crossing region of two or more belt layers is present in a region exceeding the strip width A of the belt reinforcing layer from each side edge position of the belt reinforcing layer. The original function can be fully exhibited in the cord crossing area.

It is a tread width direction sectional view showing the important section of this invention, and a development top view showing a relative relation between a belt reinforcement layer and a belt. FIG. 5 is a cross-sectional view in the tread width direction showing an example of forming a two-layer belt reinforcing layer by a spiral wound structure of a ribbon-like strip. It is an expanded sectional view of the tread width direction which shows typically the strip winding mode of one shoulder side part.

  In the embodiment shown in FIG. 1, reference numeral 1 in the figure denotes a tread portion, and reference numeral 2 in the figure denotes a toroidal carcass made of one or more carcass plies formed by winding each side portion around a bead core (not shown). The carcass that can have a radial structure 3 is a tread rubber that is disposed on the outer peripheral side of the crown region of the carcass 2 and forms a tread grounding surface.

  Here, at least one layer of reinforcing elements extending in the tread circumferential direction on the outer side in the radial direction of the crown region of the carcass 2 and inside the tread rubber 3, in the drawing, the two belt reinforcing layers 4 and the belt layer cord are mutually connected. Two or more layers extending in a crossing manner, in the drawing, a belt 7 comprising two belt layers 5 and 6 are sequentially arranged from the inner side to the outer side in the radial direction, and the belt reinforcing layer 4 is provided as a single belt. Alternatively, a plurality of reinforcing elements 4a are covered with rubber and formed by a spiral wound structure of, for example, a 3 to 20 mm wide strip.

  In the winding example of the strip 8 illustrated in FIG. 2, the strip 8 is spirally wound around one shoulder side with the central portion of the tread portion 1 as a winding start end, and the strip 8 is wound on the belt reinforcing layer 4. When the predetermined one side edge position of the belt reinforcing layer 4 is reached, the strip 8 is spirally wound toward the other shoulder side. The spiral winding is again performed in the reverse direction to the position on the near side of the winding start end of the center portion of the tread portion 1, and according to this, each of the winding start end and winding end of the strip 8 is The two-layer belt reinforcing layer 4 can be formed without being positioned on the side edge of the belt reinforcing layer 4 to be formed.

  In this case, however, the traveling direction of the spiral winding of the strip 8 is changed. One shoulder side portion and the other shoulder side portion are respectively changed to the winding direction of the strip by taking one shoulder side portion as an example in FIG. As shown schematically in the enlarged cross-sectional view in the tread width direction, the strip wound around the outermost layer generates a part of the overlapping area on the strip already laminated in two layers. In order to ensure the required interlayer rubber thickness between the belt reinforcing layer 4 and the belt 7 in such a three-layer overlapping region, the covering of the reinforcing element 4a in the vulcanization molding of the raw tire It is necessary to prevent the rubber 4b and other rubbers from being pushed away by the belt 7.

  On the other hand, since the strip wound on the innermost layer has a spiral extending form, even if the second layer strip is wound on the outer peripheral side thereof, the inner peripheral side of the second layer strip is also provided. That is, a region where the first strip of the innermost layer does not exist on the lower layer side is generated, but this region is sufficiently close to the tread circumferential direction of the spiral extending direction of the innermost layer strip. Since it can be reduced to such an extent that the required strength of the belt reinforcing layer 4 is hardly affected, there is no problem here.

  By the way, in order to ensure the thickness of the reinforcing element covering rubber 4b and other necessary interlayer rubbers in the region where the strips are overlapped in three layers, the three layers overlap in the heat and pressure such as vulcanization molding of a raw tire. It is important not to allow the covering rubber 4b or the like in the region to flow, and for this reason, here, the overlapping region of the three layers of the strip 8 does not exceed the strip width A from each side edge position of the belt reinforcing layer 4. Paying attention, the belt layer cords intersect on the premise that the belt center position of the maximum crossing width of the belt layer cord and the width center position of the belt reinforcing layer 4 are positioned corresponding to the tire radial direction. The lamination of the side edges of the belt layers 5 and 6 from the respective side edge positions of the belt reinforcing layer 4 to the outer peripheral side of the overlapping region of the three layers of the strip 8 is completely prevented, or FIG. As illustrated , Only one layer of the belt layer, it is assumed to be laminated on the outer peripheral side of the three-layer overlap region, or, it is assumed that the belt layer cord is stacked only at least two belt layers which do not cross each other.

In any of these cases, in the vulcanization molding of the raw tire, the covering rubber 4b and other rubbers in the overlapping region of the three layers of the strip 8 are sufficiently prevented from being pushed away and flowed by the belt 7. Thus, the interlayer rubber thickness as required can be reliably ensured in the three-layer overlapping region.
Here, when one or a plurality of belt layers in which the belt layer cords do not intersect with each other are laminated in the three-layer overlap region of the strip 8, the belt layer is used for vulcanization molding of the raw tire. The belt layer itself is deformed so as to escape from the three-layer overlap region without being affected by other belt layers extending in the direction in which the cords intersect.

  As shown in the figure, the belt layer cords 5a and 6a of the belt layers 5 and 6 are extended symmetrically with respect to the tire equator line. Others that incline and intersect with the tire equator line in the same direction can be selected as appropriate.

  Thus, according to this pneumatic radial tire, even if a relative shear deformation in the tread circumferential direction or the like occurs between the belt reinforcing layer 4 and the belt 7, the strip is provided in the region where the three layers overlap. By ensuring the thickness of the interlayer rubber, the shear deformation and the like can be effectively absorbed by the interlayer rubber, so that the separation between the belt reinforcing layer 4 and the belt 7 can be sufficiently prevented.

Interlaminar shear strain between belt reinforcing layer and belt, belt reinforcing layer for each of conventional tire, comparative tire and example tire having dimensions of 435 / 45R22.5 and having dimensions shown in Table 1 The heat generation temperature at the outermost position in the tire width direction of the tire and the durability until an interlayer separation failure between the belt reinforcing layer and the belt occurred in the tire were determined. Got.
In Table 1, shear strain and exothermic temperature indicate better results as the index value is smaller, and durability indicates better results as the index value is larger.

Here, the shear strain is determined by measuring the shear strain between the belt reinforcing layer and the belt when a normal load (50 kN) is statically applied, and evaluating the index,
The heat generation temperature is indexed by measuring the tire internal temperature at the outermost position in the tire width direction of the belt reinforcing layer when a normal load (50 kN) is applied and the tire is rotated at a drum rotation speed of 60 km / h. Sought by
In addition, the durability test was carried out under the condition that the drum rotation speed was 65 km / h and the tire normal load (50 kN) was added, and the tire had a separation failure between the belt reinforcing layer and the belt. The distance traveled until this occurred was evaluated by index evaluation.

According to Table 1, it can be seen that all of the example tires can improve the shear strain, the heat generation temperature, and the durability as compared with the conventional tire.
In addition, although the comparative example tire can reduce the interlaminar shear strain between them by increasing the interlayer thickness between the belt reinforcing layer and the cord crossing belt layer, the calorific value increases because the interlayer thickness is increased. As a result, the risk of thermal degradation of the interlayer rubber and the like increases.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Carcass 3 Tread rubber 4 Belt reinforcement layer 4a Reinforcing element 4b Cover rubber 5, 6 Belt layer 7 Belt 8 Strip

Claims (1)

Two belt reinforcement layers consisting of reinforcing elements extending in the circumferential direction of the tread and the belt layer cord are mutually outside the crown area of the toroidal carcass whose side part is wound around the bead core. In a pneumatic tire in which a belt composed of two or more belt layers extending intersecting each other is sequentially arranged from the inner side to the outer side in the tire radial direction,
The belt reinforcing layer is formed in a spiral shape so that a strip formed by rubber-covering one or a plurality of reinforcing elements does not overlap in the tire radial direction between adjacent strips in the tire width direction in at least a part of the belt reinforcing layer. It is formed by a spirally wound structure configured in a wound state, and at least a part of a three-layer structure is formed on each side of the belt reinforcing layer, and the width of the belt reinforcing layer strip is set to A When
Maximum crossing width of belt layer cord of belt <(belt reinforcing layer width-2A)
And a pneumatic radial tire in which the center position of the maximum width of the belt layer cord is positioned in the tire radial direction so as to correspond to the center position of the width of the belt reinforcing layer.

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