Patent Description:
For example, as described in Patent Document <NUM>, a tire having a carcass ply is known.

As a further example, Patent Document <NUM> discloses a pneumatic tire comprising a carcass as a skeletal structure composed of at least one carcass ply extending toroidally between a pair of bead portions, at least one layer of a belt located on the outer side of the carcass in the tire radial direction of the crown portion. The tire is provided with a cushion rubber and a tread rubber forming a tread portion in turn on the outer side of the belt in the tire radial direction, and a composite fiber containing a conductive fiber and a nonconductive fiber is extended at least from the pair of bead portions to portions in contact with the cushion rubber or a pair of belt under cushions, so as to expose the composite fiber to both surfaces of the carcass at the outer and inner sides of the tire.

As a further example, Patent Document <NUM> discloses a pneumatic tire that is provided with a belt layer arranged on the outside of a carcass in the radial direction of a crown part, and a rubber chafer is disposed on the external surface of a bead part in the width direction of the tire. A cushion rubber and a tread rubber are sequentially disposed on the outside of the belt layer in the radial direction of the tire; composite fibers that include conductive fibers and nonconductive fibers are disposed at least from the bead part up to the position of contact with the cushion rubber or the position of contact with a belt under-cushion disposed on the outer end of the belt layer in the width direction of the tire, so as to be exposed on at least one surface on the outside or inside of the tire; and the rubber chafer contains carbon black having a nitrogen adsorption specific surface area of <NUM>-<NUM> m2/g.

As a further example, Patent Document <NUM> discloses a rubber tire, and its preparation, composed of carbon black reinforced rubber carcass with an outer, circumferential rubber tread construction of a rubber composition having a relatively high electrical resistivity. The tire tread construction has an electrically conductive filamentary thread stitched through the tread construction and extending between the inner surface of the tread to its outer surface. An electrically conductive path is thereby created through the tire tread.

In the above tires, reduction of rolling resistance is required. In order to reduce the rolling resistance, for example, an amount of carbon contained in a carcass rubber in a carcass ply may be reduced. However, when the amount of carbon contained in the carcass rubber is reduced, volume resistivity of the carcass rubber increases, and a conductive path from a bead portion to a tread surface portion may be blocked by the carcass ply. Therefore, it may be difficult for static electricity transmitted from a vehicle to the bead portion to be released from the tread surface portion to the ground.

In view of the above circumstances, one aspect of the present invention is to provide a tire having a structure in which static electricity from a vehicle can be easily released to the ground regardless of conductivity of the carcass ply.

According to an aspect of the present invention, there is provided a tire including: a tread portion; a sidewall portion; a bead portion; a bead core provided in the bead portion; and a carcass ply covering at least a portion around the bead core, in which the carcass ply includes a sewn portion in which a conductive thread is sewn. The tire further comprises a conductive portion extending along the carcass ply and located outside the carcass ply in a tire radial direction in the tread portion; and a chafer portion having conductivity and covering at least a portion around the carcass ply. The sewn portion is sewn through the carcass ply, and includes a first seam portion which is in contact with the chafer portion and a second seam portion which is in contact with the conductive portion. A volume resistivity of the conductive portion is smaller than a volume resistivity of the chafer portion.

According to one aspect of the present invention, there is provided a tire having a structure in which static electricity from a vehicle is easily released to the ground regardless of conductivity of a carcass ply.

Hereinafter, a tire according to an embodiment of the present invention will be described with reference to the drawings. Further, in the following drawings, a scale and a number of each structure may be different from a scale and a number of an actual structure in order to make each configuration easy to understand.

A Z-axis direction shown in each drawing is a direction parallel to a tire radial direction. For example, the tire radial direction in <FIG> is an up-down direction. In a portion of the tire shown in each drawing, a positive side in the Z-axis direction, that is, for example, an upper side in <FIG> is an outside in the tire radial direction, and a negative side in the Z-axis direction, that is, for example, a lower side in <FIG> is an inside in the tire radial direction.

A Y-axis direction shown in each drawing is a direction parallel to a tire width direction. In <FIG>, the tire width direction is a left-right direction. In the following descriptions, for a certain object, a side closer to a tire equatorial portion CL in the tire width direction is referred to as an "inside in the tire width direction", and a side far from the tire equatorial portion CL in the tire width direction is referred to as an "outside in the tire width direction". The tire equatorial portion CL is a center in the tire width direction of the tire. In a portion of the tire shown in each drawing, a negative side in the Y-axis direction, that is, for example, a right side of <FIG> is an inside in the tire width direction, and a positive side in the Y-axis direction, that is, for example, a left side of <FIG> is an outside in the tire width direction.

Further, a circumferential direction of the tire around a central axis (not shown) is referred to as a tire circumferential direction. The X-axis direction shown in each drawing is a direction orthogonal to both the Z-axis direction and the Y-axis direction, and indicates the circumferential direction in the cross section of the tire shown in each drawing.

<FIG> shows only a portion of the cross section of a tire <NUM> of an embodiment of the present invention in the tire circumferential direction, which is located on one side in the tire width direction from the tire equatorial portion CL. In the cross section of a portion of the tire <NUM> in the tire circumferential direction, a portion located on the other side of the tire equatorial portion CL in the tire width direction is disposed symmetrically with the portion shown in <FIG> in the tire width direction in a state where the tire equatorial portion CL is interposed therebetween. In the following description, the portion of the tire <NUM> shown in <FIG> will be described, and the portion of the tire <NUM> located on the other side in the tire width direction from the tire equatorial portion CL may be omitted.

As shown in <FIG>, the tire <NUM> of the present embodiment of the invention includes a tread portion <NUM>, a sidewall portion <NUM>, and a bead portion <NUM>.

The tread portion <NUM> is disposed outside the bead portion <NUM> in the tire radial direction, and is located at an outer end portion of the tire <NUM> in the tire radial direction. The tread portion <NUM> has an annular shape extending in the tire circumferential direction. The tread portion <NUM> has a tread surface portion 11a which is a ground contact surface of the tire <NUM>. The tread surface portion 11a is a portion of an outer surface of the tread portion <NUM> in the tire radial direction.

For example, the tread surface portion 11a is the ground contact surface of the tread portion <NUM> in a state where the tire <NUM> is mounted on a standard rim specified in "JATMA Year Book", and the tire <NUM> is filled with the internal pressure (hereinafter, referred to as a specified internal pressure) of <NUM>% of an air pressure (maximum air pressure) corresponding to a maximum load capacity (internal pressure - bold load of load capacity correspondence table) in an applicable size and ply rating in "JATMA Year Book" such that a maximum load corresponding to the maximum load capacity is applied.

For example, when a region where the tire <NUM> is produced or used is other than Japan, the tread surface portion 11a is the ground contact surface of the tread portion <NUM> in a state where the tire <NUM> is based on an industrial standard (for example, "TRA Year Book" in the United States, "ETRTO Standard Manual" in Europe, or the like) applied to the region other than Japan.

The sidewall portion <NUM> extends inward in the tire radial direction from an outer end portion of the tread portion <NUM> in the tire width direction. The sidewall portion <NUM> connects the outer end portion of the tread portion <NUM> in the tire width direction and the bead portion <NUM>.

The bead portion <NUM> is connected to an inner end portion of the sidewall portion <NUM> in the tire radial direction. A bead core <NUM> is provided in the bead portion <NUM>. More specifically, the bead core <NUM> is embedded in the bead portion <NUM>.

The tire <NUM> includes a carcass layer <NUM> which serves as a skeleton. For example, the tire <NUM> is configured by assembling a first chafer portion <NUM>, a tire body <NUM>, a belt layer <NUM>, and a belt reinforcing layer <NUM> to the carcass layer <NUM>. The carcass layer <NUM> is provided so as to straddle the tread portion <NUM>, the sidewall portion <NUM>, and the bead portion <NUM>. The carcass layer <NUM> has an annular shape extending along the tire circumferential direction. As shown in <FIG> and <FIG>, the carcass layer <NUM> has a carcass ply <NUM> and a conductive portion <NUM>.

The carcass ply <NUM> covers at least a portion around the bead core <NUM>. The carcass ply <NUM> in the present embodiment extends from the tread portion <NUM> to the bead portion <NUM> via the sidewall portion <NUM> and is folded outward around the bead core <NUM> in the tire width direction. The carcass ply <NUM> has an annular shape extending along the tire circumferential direction. As shown in <FIG>, the carcass ply <NUM> has a carcass rubber 51a and a plurality of ply cords 51b. The carcass ply <NUM> is configured by embedding the plurality of ply cords 51b in the carcass rubber 51a.

In the present embodiment of the invention, a loss tangent tan δ of the carcass rubber 51a is relatively small. The loss tangent tan δ becomes smaller as a carbon content in the carcass rubber 51a is smaller. The smaller the loss tangent tan δ of the carcass rubber 51a, the smaller the rolling resistance of the tire <NUM>. In the present embodiment of the invention, the carcass rubber 51a is relatively difficult to conduct electricity. As a result, the conductivity of the carcass ply <NUM> in the present embodiment is relatively low.

The plurality of ply cords 51b extend from the tread portion <NUM> to the bead portion <NUM> via the sidewall portion <NUM> and are folded outward in the tire width direction around the bead core <NUM> in a state of being embedded in the carcass rubber 51a. The plurality of ply cords 51b are disposed at intervals along the tire circumferential direction. For example, the ply cord 51b is an organic fiber cord or the like.

The conductive portion <NUM> is provided on the outer surface of the carcass ply <NUM>. As shown in <FIG>, the conductive portion <NUM> extends along the carcass ply <NUM>. The conductive portion <NUM> is located outside the carcass ply <NUM> in the tire radial direction in the tread portion <NUM>. In the present embodiment of the invention, the conductive portion <NUM> extends from the tread portion <NUM> to at least the inside of the bead core <NUM> in the tire radial direction. In the present embodiment of the invention, the conductive portion <NUM> extends from the tread portion <NUM> to the bead portion <NUM> via the sidewall portion <NUM>, is folded around the bead core <NUM> to the outside in the tire width direction, and extends to the outside of the bead core <NUM> in the tire width direction.

An outer end portion of the conductive portion <NUM> folded around the bead core <NUM> in the tire radial direction is disposed at the same position in the tire radial direction as an outer end portion of the carcass ply <NUM> folded around the bead core <NUM> in the tire radial direction. In the bead portion <NUM>, the conductive portion <NUM> is provided inside the carcass ply <NUM> folded around the bead core <NUM>. As shown in <FIG>, the plurality of conductive portions <NUM> are attached to the outer surface of the carcass rubber 51a in the tire radial direction inside the bead core <NUM> in the tire radial direction.

In the present embodiment of the invention, the conductive portion <NUM> is a thread-like member containing metal. For example, the conductive portion <NUM> is a conductive thread in which a metal fiber such as stainless steel is wound around an organic fiber. The plurality of conductive portions <NUM> are provided at intervals along the tire circumferential direction.

<FIG> shows, as an example, a state in which the conductive portion <NUM> is located outside the ply cord 51b in the tire radial direction. A positional relationship between the plurality of conductive portions <NUM> and the plurality of ply cords 51b in the tire circumferential direction is not particularly limited. That is, in <FIG>, a position of the conductive portion <NUM> in the left-right direction may deviate from a position of the ply cord 51b in the left-right direction. Further, the number of the conductive portions <NUM> and the number of the ply cords 51b may be the same or different.

The conductive portion <NUM> has conductivity. Volume resistivity of the conductive portion <NUM> is smaller than volume resistivity of the chafer portion <NUM> described below.

A first chafer portion <NUM> has conductivity. The first chafer portion <NUM> is a rubber member or a composite member of fibers and rubber. As shown in <FIG>, the first chafer portion <NUM> covers a portion of the carcass ply <NUM> provided on the bead portion <NUM> from the inside in the tire radial direction and from both sides in the tire width direction. The portion of the carcass ply <NUM> provided on the bead portion <NUM> includes a portion of the carcass ply <NUM> that covers the bead core <NUM> from the inside in the tire radial direction and from both sides in the tire width direction. In the following description, the portion of the carcass ply <NUM> provided on the bead portion <NUM> is referred to as a core covering portion <NUM>. The core covering portion <NUM> extends from the inside of the bead core <NUM> in the tire width direction through the inside of the bead core <NUM> in the tire radial direction to the outside of the bead core <NUM> in the tire width direction. The first chafer portion <NUM> has an annular shape extending along the tire circumferential direction.

The first chafer portion <NUM> has a radial covering portion <NUM> and widthwise covering portions <NUM> and <NUM>. The radial covering portion <NUM> is a portion that covers the core covering portion <NUM> of the carcass ply <NUM> from the inside in the tire radial direction. The radial covering portion <NUM> extends in the tire width direction. The widthwise covering portions <NUM> and <NUM> are portions that cover the core covering portion <NUM> of the carcass ply <NUM> from both sides in the tire width direction. The widthwise covering portion <NUM> extends from an outer end portion of the radial covering portion <NUM> in the tire width direction to the outside in the tire radial direction, and covers the core covering portion <NUM> from the outside in the tire width direction. The widthwise covering portion <NUM> extends from an inner end portion of the radial covering portion <NUM> in the tire width direction to the outside in the tire radial direction, and covers the core covering portion <NUM> from the inside in the tire width direction. The outer end portions of the widthwise covering portions <NUM> and <NUM> in the tire radial direction are located inside the outer end portion in the tire radial direction in the portion of the carcass ply <NUM> that is folded around the bead core <NUM>, in the tire radial direction.

As shown in <FIG>, the tire body <NUM> has a tread rubber <NUM> and a sidewall rubber <NUM>.

The tread rubber <NUM> is a portion forming a portion of the tread portion <NUM>, and has an annular shape extending along the tire circumferential direction. The tread rubber <NUM> is provided on the outer side of the carcass layer <NUM> in the tire radial direction. The tread rubber <NUM> is connected to the carcass layer <NUM> via the belt layer <NUM> and the belt reinforcing layer <NUM>. In <FIG>, the carcass layer <NUM> is separated from the tread rubber <NUM>, the belt layer <NUM>, and the belt reinforcing layer <NUM> in order to show each portion schematically in an easy-to-understand manner.

The tread rubber <NUM> has a tread under cushion <NUM>, a base layer <NUM>, a cap layer <NUM>, a mini side <NUM>, and an antenna rubber <NUM>.

The tread under cushion <NUM>, the base layer <NUM>, and the cap layer <NUM> are laminated in this order from the inside in the tire radial direction to the outside in the tire radial direction. An outer surface of the cap layer <NUM> in the tire radial direction constitutes the tread surface portion 11a. The mini side <NUM> is connected to outer end portions of the laminated tread under cushion <NUM>, the base layer <NUM> and the cap layer <NUM> in the tire width direction.

The antenna rubber <NUM> is embedded so as to straddle the base layer <NUM> and the cap layer <NUM>. The antenna rubber <NUM> penetrates the base layer <NUM> and the cap layer <NUM> in the tire radial direction. An inner end portion of the antenna rubber <NUM> in the tire radial direction is connected to the outer surface of the tread under cushion <NUM> in the tire radial direction. An outer end portion of the antenna rubber <NUM> in the tire radial direction is exposed on the outer surface of the cap layer <NUM> in the tire radial direction, and forms a portion of the tread surface portion 11a. The antenna rubber <NUM> may extend intermittently, may extend continuously, or may be scattered in the tire circumferential direction.

The base layer <NUM>, the cap layer <NUM>, and the mini side <NUM> are relatively difficult to conduct electricity and have low conductivity. The tread under cushion <NUM> and the antenna rubber <NUM> are relatively easy to conduct electricity and have conductivity.

The sidewall rubber <NUM> is a portion forming a portion of the sidewall portion <NUM> and a portion of the bead portion <NUM>, and has an annular shape extending along the tire circumferential direction. The sidewall rubber <NUM> is provided outside the carcass layer <NUM> in the tire width direction. The sidewall rubber <NUM> is connected to the carcass layer <NUM>. The outer end portion of the sidewall rubber <NUM> in the tire radial direction is connected to the outer end portion of the tread rubber <NUM> in the tire width direction. In <FIG>, in order to show each portion schematically in an easy-to-understand manner, the sidewall rubber <NUM> and the carcass layer <NUM> are shown apart from each other, and the sidewall rubber <NUM> and the tread rubber <NUM> are shown apart from each other.

The sidewall rubber <NUM> has a sidewall rubber main body portion <NUM> and a second chafer portion <NUM>.

The sidewall rubber main body portion <NUM> is a portion forming a portion of the sidewall portion <NUM>. The outer end portion of the sidewall rubber main body portion <NUM> in the tire radial direction extends inward in the tire width direction and is located between the carcass layer <NUM> and the tread rubber <NUM>, the belt layer <NUM>, and the belt reinforcing layer <NUM>.

The second chafer portion <NUM> is a portion that constitutes a portion of the bead portion <NUM>. The second chafer portion <NUM> is connected to an inner end portion of the sidewall rubber main body portion <NUM> in the tire radial direction. The second chafer portion <NUM> covers the core covering portion <NUM> in the carcass layer <NUM> from the outside in the tire width direction. The second chafer portion <NUM> is connected to the core covering portion <NUM> and the widthwise covering portion <NUM> of the first chafer portion <NUM> from the outside in the tire width direction. In addition, in <FIG>, in order to show each portion in an easy-to-understand manner, the second chafer portion <NUM> and the core covering portion <NUM> are shown apart from each other, and the second chafer portion <NUM> and the widthwise covering portion <NUM> are shown apart from each other.

A rubber material constituting the sidewall rubber main body portion <NUM> and a rubber material constituting the second chafer portion <NUM> have different volume resistivity from each other. The sidewall rubber main body portion <NUM> is relatively difficult to conduct electricity. The second chafer portion <NUM> is relatively easy to conduct electricity and has conductivity.

In the present embodiment of the invention, the first chafer portion <NUM> and the second chafer portion <NUM> described above constitute a chafer portion <NUM>. That is, the tire <NUM> has the chafer portion <NUM> that covers at least a portion around the carcass ply <NUM>. In the present embodiment of the invention, the chafer portion <NUM> covers at least the inside of the core covering portion <NUM> in the tire radial direction and the outside of the core covering portion <NUM> in the tire width direction. The chafer portion <NUM> has conductivity. In the chafer portion <NUM>, volume resistivity of the first chafer portion <NUM> and volume resistivity of the second chafer portion <NUM> may be the same as each other or may be different from each other. In the present embodiment of the invention, the chafer portion <NUM> covers the inside of the core covering portion <NUM> in the tire radial direction and both sides of the core covering portion <NUM> in the tire width direction, and is connected to the core covering portion <NUM>. The chafer portion <NUM> is a portion that protects the carcass layer <NUM> from friction with a rim to which the tire <NUM> is attached.

The belt layer <NUM> is embedded in the tread portion <NUM>. The belt layer <NUM> is laminated on the outer side of the carcass layer <NUM> in the tire radial direction. The belt layer <NUM> is connected to the carcass ply <NUM> and the conductive portion <NUM>. The belt layer <NUM> is located between the tread rubber <NUM> and the carcass layer <NUM> in the tire radial direction. Although not shown, the belt layer <NUM> is configured by embedding a plurality of steel cords in a belt rubber. The belt rubber of the belt layer <NUM> is relatively easy to conduct electricity and has conductivity. As a result, the belt layer <NUM> has conductivity.

The belt reinforcing layer <NUM> is laminated on the outer side of the belt layer <NUM> in the tire radial direction. The belt reinforcing layer <NUM> is located between the tread rubber <NUM> and the belt layer <NUM> in the tire radial direction. The outer surface of the belt reinforcing layer <NUM> in the tire radial direction is connected to the inner surface of the tread under cushion <NUM> of the tread rubber <NUM> in the tire radial direction.

The belt reinforcing layer <NUM> is configured by, for example, winding a composite cord made of rubber and nylon around an outer circumferential portion of the belt layer <NUM> a plurality of times. One roll of the composite cord constituting the belt reinforcing layer <NUM> is disposed with a gap <NUM> from each other along the tire width direction. Although not shown, the tread under cushion <NUM> and the belt layer <NUM> between which the belt reinforcing layer <NUM> is interposed in the tire radial direction are connected to each other in the gap <NUM> between one roll of the belt reinforcing layer <NUM>. The belt reinforcing layer <NUM> is relatively difficult to conduct electricity.

The carcass ply <NUM> is provided with a sewn portion <NUM> in which a conductive thread is sewn. In the present embodiment, the sewn portion <NUM> is provided in a portion of the carcass ply <NUM> located inside the bead core <NUM> in the tire radial direction. In the present embodiment, the sewn portion <NUM> extends along the tire circumferential direction as shown in <FIG> and <FIG>. The sewn portion <NUM> is provided, for example, along the entire circumference of the carcass ply <NUM> along the tire circumferential direction. That is, in the present embodiment, the sewn portion <NUM> has an annular shape extending along the tire circumferential direction.

The sewn portion <NUM> is sewn through the carcass ply <NUM>. The sewn portion <NUM> penetrates the carcass ply <NUM> in the tire radial direction, for example, as shown in <FIG>. More specifically, the sewn portion <NUM> penetrates the carcass rubber 51a in the tire radial direction. The sewn portion <NUM> has at least one first seam portion 80a and at least one second seam portion 80b. In the present embodiment of the invention, a plurality of the first seam portions 80a and the second seam portions 80b are provided side by side along the circumferential direction.

The first seam portion 80a is located inside a portion of the carcass ply <NUM>, which is located inside the bead core <NUM> in the tire radial direction, in the tire radial direction. At least one of the first seam portions 80a is in contact with the chafer portion <NUM>. In the present embodiment, for example, all the first seam portions 80a are in contact with the radial covering portion <NUM> of the first chafer portion <NUM>.

The second seam portion 80b is located outside a portion of the carcass ply <NUM>, which is located inside the bead core <NUM> in the tire radial direction, in the tire radial direction. At least one of the second seam portions 80b is in contact with the conductive portion <NUM>. As a result, the sewn portion <NUM> comes into contact with both the chafer portion <NUM> and the conductive portion <NUM>, and electrically connects the chafer portion <NUM> and the conductive portion <NUM>.

In the present embodiment of the invention, the second seam portion 80b is provided so as to straddle the outside of the conductive portion <NUM> in the tire radial direction in the tire circumferential direction, and is in contact with the conductive portion <NUM> from the outside in the tire radial direction. As a result, in the present embodiment of the invention, the sewn portion <NUM> has at least one of the conductive portions <NUM> sewn into the carcass ply <NUM>. As shown in <FIG>, in the present embodiment of the invention, the sewn portion <NUM> has a plurality of conductive portions <NUM> sewn into the carcass ply <NUM>. That is, in the present embodiment of the invention, each of the plurality of second seam portions 80b is in contact with the conductive portion <NUM>. As a result, the sewn portion <NUM> is in contact with the plurality of conductive portions <NUM>. In the present embodiment of the invention, the sewn portion <NUM> is in contact with all the conductive portions <NUM>. The plurality of second seam portions 80b include a second seam portion 80b that does not come into contact with the conductive portion <NUM>.

As shown in <FIG>, in the present embodiment of the invention, the sewn portion <NUM> is configured such that a bobbin thread <NUM> and a needle thread <NUM> are sewn into the carcass ply <NUM> by, for example, a sewing machine. The bobbin thread <NUM> and the needle thread <NUM> are entangled with each other and are in contact with each other. Accordingly, the bobbin thread <NUM> and the needle thread <NUM> are electrically connected. The bobbin thread <NUM> is a conductive thread that constitutes the plurality of first seam portions 80a. The needle thread <NUM> is a conductive thread that constitutes the plurality of second seam portions 80b. A portion where the bobbin thread <NUM> and the needle thread <NUM> are entangled with each other is embedded in the carcass rubber 51a of the carcass ply <NUM>, for example.

The bobbin thread <NUM> and the needle thread <NUM> are, for example, thread-like members containing metal. The bobbin thread <NUM> and the needle thread <NUM> are configured by, for example, winding a metal fiber such as stainless steel around an organic fiber. The bobbin thread <NUM> and the needle thread <NUM> have conductivity. Volume resistivity of the bobbin thread <NUM> and volume resistivity of the needle thread <NUM> may be the same or different from each other.

As shown in <FIG>, the tire <NUM> includes a conductive path CP that releases static electricity from the vehicle from a rim on which the tire <NUM> is mounted to the ground. The conductive path CP is a path through which static electricity transmitted from the rim in the tire <NUM> passes, and extends from the second chafer portion <NUM> to the tread surface portion 11a through the first chafer portion <NUM>, the sewn portion <NUM>, the conductive portion <NUM>, the belt layer <NUM>, the gap <NUM> of the belt reinforcing layer <NUM>, the tread under cushion <NUM>, and the antenna rubber <NUM> in this order. As a result, the static electricity of the vehicle transmitted from the rim can be released from the tread surface portion 11a to the ground.

In the sewn portion <NUM> of the present embodiment of the invention, the static electricity is transmitted from the bobbin thread <NUM> to the needle thread <NUM>. Further, as described above, the tread under cushion <NUM> and the belt layer <NUM> are connected to each other in the gap <NUM> of the belt reinforcing layer <NUM>. Therefore, the static electricity that has flowed from the conductive portion <NUM> to the belt layer <NUM> flows from the gap <NUM> to the tread under cushion <NUM>.

According to the present embodiment of the invention, the carcass ply <NUM> includes the sewn portion <NUM> in which a conductive thread is sewn. Therefore, in the portion of the carcass ply <NUM> where the sewn portion <NUM> is provided, electricity can easily pass through the sewn portion <NUM>. As a result, even when the conductivity of the carcass ply <NUM> is low, static electricity from the vehicle can pass through the carcass ply <NUM> by the sewn portion <NUM>. Accordingly, regardless of the conductivity of the carcass ply <NUM>, it is possible to obtain the tire <NUM> having a structure that allows static electricity from the vehicle to be easily released to the ground. Therefore, the amount of carbon contained in the carcass rubber 51a of the carcass ply <NUM> can be reduced to reduce the rolling resistance of the tire <NUM>, and the static electricity of the vehicle can be suitably released to the ground.

Further, according to the present embodiment of the invention, the sewn portion <NUM> is provided in the portion of the carcass ply <NUM> located inside the bead core <NUM> in the tire radial direction. Therefore, the portion of the carcass ply <NUM> having the sewn portion <NUM> can be easily brought into contact with the chafer portion <NUM>. As a result, the static electricity from the vehicle transmitted from the rim to the chafer portion <NUM> can easily pass through the carcass ply <NUM> by the sewn portion <NUM>. Therefore, the static electricity from the vehicle can be more suitably released to the ground.

Further, for example, when a raw tire is put into a mold and vulcanized to make a tire <NUM>, a rubber of the raw tire is deformed according to a shape of the mold. In this case, the rubber is less likely to be deformed inside the bead core <NUM> in the tire radial direction. Therefore, by providing the sewn portion <NUM> in the portion of the carcass ply <NUM> located inside the bead core <NUM> in the tire radial direction, the bobbin thread <NUM> and the needle thread <NUM> constituting the sewn portion <NUM> are not easily affected by the deformation of the rubber when the raw tire is vulcanized in the mold. As a result, it is possible to prevent the bobbin thread <NUM> and the needle thread <NUM> from being cut.

Further, according to the present embodiment of the invention, the sewn portion <NUM> is sewn through the carcass ply <NUM> and includes the first seam portion 80a which is in contact with the chafer portion <NUM> and the second seam portion 80b which is in contact with the conductive portion <NUM>. Therefore, even when the volume resistivity of the carcass rubber 51a in the carcass ply <NUM> is relatively large and the conductivity of the carcass ply <NUM> is low, the static electricity from the vehicle transmitted from the rim to the chafer portion <NUM> can be transferred to the conductive portion <NUM> via the sewn portion <NUM>. As a result, the static electricity from the vehicle can be transferred to the tread portion <NUM> via the conductive portion <NUM>, and the static electricity can be released from the tread surface portion 11a to the ground at the tread portion <NUM>. Therefore, the static electricity from the vehicle can be more suitably released to the ground.

Further, the volume resistivity of the conductive portion <NUM> is smaller than the volume resistivity of the chafer portion <NUM>. Therefore, it is easy to suitably reduce the volume resistivity of the conductive portion <NUM>. As a result, the static electricity can suitably flow to the conductive portion <NUM> that forms a relatively long conductive path CP from the bead portion <NUM> to the tread portion <NUM>. Therefore, the static electricity from the vehicle can be more easily released to the ground.

Further, according to the present embodiment of the invention, the conductive portion <NUM> is a thread-like member containing metal. Therefore, it is easy to reduce the volume resistivity of the conductive portion <NUM> more suitably, and the static electricity is more easily flown from the bead portion <NUM> to the tread portion <NUM> by the conductive portion <NUM>. Therefore, the static electricity from the vehicle can be more easily released to the ground. Further, according to the present embodiment of the invention, the plurality of conductive portions <NUM> are provided at intervals along the tire circumferential direction. Therefore, it is possible to increase the conductive path CP that allows the static electricity to flow from the bead portion <NUM> to the tread portion <NUM>, and the static electricity is more easily flown from the bead portion <NUM> to the tread portion <NUM> by the conductive portion <NUM>. Therefore, the static electricity from the vehicle can be more suitably released to the ground.

Further, according to the present embodiment of the invention, the sewn portion <NUM> extends along the tire circumferential direction. Therefore, the sewn portion <NUM> can easily cross the conductive portion <NUM>, and the second seam portion 80b in the sewn portion <NUM> can be easily brought into contact with the conductive portion <NUM>. Further, as in the present embodiment of the invention, one sewn portion <NUM> can be easily brought into contact with a plurality of conductive portions <NUM>.

Further, according to the present embodiment of the invention, the sewn portion <NUM> is in contact with the plurality of conductive portions <NUM> via the second seam portion 80b. Therefore, by providing one sewn portion <NUM>, the plurality of conductive portions <NUM> can be connected to the chafer portion <NUM>, and it is possible to increase the conductive path CP that allows static electricity to flow from the bead portion <NUM> to the tread portion <NUM>. Therefore, the static electricity from the vehicle can be suitably released to the ground while reducing the time and effort required to provide the sewn portion <NUM>.

Further, according to the present embodiment of the invention, the sewn portion <NUM> has at least one of the conductive portions <NUM> sewn into the carcass ply <NUM>. Therefore, the second seam portion 80b can be more reliably brought into contact with the conductive portion <NUM>.

Further, according to the present embodiment of the invention, the carcass rubber 51a is relatively difficult to conduct electricity. Therefore, it is difficult for the static electricity from the vehicle to pass through the carcass ply <NUM>. However, as described above, according to the present embodiment, the static electricity from the vehicle is easily released to the ground regardless of the conductivity of the carcass ply <NUM>. That is, the effect that the static electricity is easily released to the ground regardless of the conductivity of the carcass ply <NUM> described above can be obtained more usefully in a configuration in which the carcass rubber 51a is relatively difficult to conduct electricity.

The present invention is not limited to the above embodiments, and the following configurations can also be adopted.

The sewn portion is not particularly limited as long as it is provided in the carcass ply. The sewn portion may be provided at any position in the carcass ply.

In the above-described embodiment, the sewn portion <NUM> has the structure in which two conductive threads are entangled and sewn, but the sewn portion <NUM> is not limited to this. The sewn portion may be formed by sewing, for example, one conductive thread. In this case, for example, one conductive thread penetrates the carcass ply in the tire radial direction to form each of the first seam portion and the second seam portion. The conductive thread constituting the sewn portion is not particularly limited as long as it is a conductive thread.

Further, the method of sewing the conductive thread when forming the sewn portion is not particularly limited. The sewn portion may not be sewn with the conductive portion. The second seam portion may be in contact with the conductive portion from the inside in the tire radial direction. The sewn portion may be provided on only one of the portions of the carcass ply provided on each of the pair of bead portions, or may be provided on both thereof.

A plurality of sewn portions may be provided as in a sewn portion <NUM> of a tire <NUM> shown in <FIG>. The plurality of sewn portions <NUM> are disposed so as to be spaced apart from each other along the tire circumferential direction. Each of the plurality of sewn portions <NUM> extends in the tire circumferential direction. A dimension of the sewn portion <NUM> in the tire circumferential direction is smaller than a distance between the conductive portions <NUM> adjacent to each other in the tire circumferential direction. The sewn portion <NUM> is configured by sewing two conductive threads in the same manner as the sewn portion <NUM> described above, for example. Each of the plurality of sewn portions <NUM> is in contact with the conductive portions <NUM> that are different from each other. Other configurations of the tire <NUM> are the same as the other configurations of the tire <NUM> described above.

According to this configuration, a region where the conductive thread is sewn in the carcass ply <NUM> can be easily reduced as compared with the case where the sewn portion is provided over the entire circumference in the tire circumferential direction. Specifically, for example, since it is not necessary to sew the conductive thread between the sewn portions <NUM> in the tire circumferential direction, the region where the conductive thread is sewn can be made smaller than that in the case where the sewn portion is provided so as to straddle the adjacent conductive portions <NUM>. As a result, the total amount of conductive threads required to form the sewn portion <NUM> can be reduced. Therefore, a manufacturing cost of the tire <NUM> can be reduced. In addition, an amount of work for sewing the conductive thread can be reduced.

In the configuration shown in <FIG>, positions of the plurality of sewn portions <NUM> in the tire width direction may be displaced from each other, for example. Further, the plurality of sewn portions <NUM> may be provided side by side in the tire width direction. Further, one sewn portion <NUM> may come into contact with two or more conductive portions <NUM>. The conductive portion <NUM> with which the sewn portion <NUM> is not in contact may be provided.

The carcass ply may include another sewn portion at a position different from the sewn portion described above. Other sewn portions may be provided, for example, on at least one of the carcass plies located on both sides of the bead core in the tire width direction. When the other sewn portion is provided on the outside of the bead core of the carcass ply in the tire width direction, the other sewn portion may be in contact with the second chafer portion and the conductive portion such that the second chafer portion and the conductive portion are connected to each other.

The conductive portion is not particularly limited as long as it extends along the carcass ply, is located outside the carcass ply in the tire radial direction in the tread portion, and has conductivity. The conductive portion may not contain metal. The conductive portion may be made of, for example, a conductive rubber. The conductive portion may not be a thread-like member, and may be a layered member laminated on the carcass ply.

The chafer portion is not particularly limited as long as it has conductivity and covers at least a portion around the carcass ply. For example, in the above-described embodiment, the first chafer portion <NUM> may not have either or both of the widthwise covering portions <NUM> and <NUM>. When the first chafer portion <NUM> does not have the widthwise covering portion <NUM>, for example, the first chafer portion <NUM> is connected to the second chafer portion <NUM> at the outer end portion of the radial covering portion <NUM> in the tire width direction. The first chafer portion and the second chafer portion may be integrally molded.

In the above-described embodiment, the carcass ply has one layer of carcass ply, but may be two or more layers of carcass ply. That is, the carcass ply may be configured by laminating a plurality of carcass plies having the same configuration as the carcass ply <NUM> of the above-described embodiment. In this case, for example, the sewn portion may connect the chafer portion and the conductive portion by collectively penetrating a plurality of layers of carcass ply in the tire radial direction.

Further, when the carcass ply has two or more layers, the sewn portion may be configured by sewing different conductive threads for each layer. Specifically, for example, when the carcass ply is configured by laminating a first carcass ply and a second carcass ply located outside in the tire radial direction of the first carcass ply in the tread portion, the sewn portion may have a first sewn portion sewn into the first carcass ply and a second sewn portion sewn into the second carcass ply. In this case, the first sewn portion and the second sewn portion are electrically connected to each other, the first sewn portion has a first seam portion which is in contact with the chafer portion, and the second sewn portion has a second seam portion which is in contact with the conductive portion. The first sewn portion and the second sewn portion may be electrically connected to each other by being in direct contact with each other, or may be electrically connected to each other via another conductive portion provided between the first carcass ply and the second carcass ply. Another conductive portion may have the same configuration as the conductive portion <NUM> described above, except that it is disposed between the first carcass ply and the second carcass ply, for example. The first sewn portion and the second sewn portion can each adopt the same configuration as the sewn portion <NUM> of the above-described embodiment.

The carcass layer may have an inner liner attached to the inner surface of the carcass ply.

The configuration of the tread portion is not particularly limited as long as static electricity can flow from the conductive portion extending to the tread portion to the tread surface portion.

The tire of the above-described embodiment may be used in any vehicle.

The configurations described in the present specification can be appropriately combined within a range that does not contradict each other.

According to one aspect of the tire of the present invention, the carcass ply includes a sewn portion in which a conductive thread is sewn. Therefore, it is possible to easily conduct electricity through the sewn portion in a portion of the carcass ply where the sewn portion is provided. As a result, even when the conductivity of the carcass ply is low, the static electricity from the vehicle can be passed through the carcass ply by the sewn portion. Therefore, regardless of the conductivity of the carcass ply, it is possible to obtain the tire having a structure that allows static electricity from the vehicle to be easily released to the ground. Therefore, the amount of carbon contained in the carcass rubber of the carcass ply can be reduced to reduce the rolling resistance of the tire, and the static electricity of the vehicle can be suitably released to the ground.

The sewn portion may be provided in a portion of the carcass ply located inside the bead core in the tire radial direction.

According to this configuration, the portion of the carcass ply having the sewn portion can be easily brought into contact with the chafer portion. As a result, static electricity from a vehicle transmitted from a rim to the chafer portion can easily pass through the carcass ply by the sewn portion. Therefore, the static electricity from the vehicle can be more suitably released to the ground.

Further, for example, when a raw tire is put into a mold and vulcanized to make a tire, a rubber of the raw tire is deformed according to a shape of the mold. In this case, the rubber is less likely to be deformed inside the bead core in the tire radial direction. Therefore, by providing the sewn portion in the portion of the carcass ply located inside the bead core in the tire radial direction, the conductive thread constituting the sewn portion are not easily affected by the deformation of the rubber when the raw tire is vulcanized in the mold. As a result, it is possible to prevent the conductive thread from being cut.

The tire further comprises a conductive portion extending along the carcass ply and located outside the carcass ply in the tire radial direction in the tread portion, and a chafer portion having conductivity and covering at least a portion around the carcass ply, and the sewn portion includes the first seam portion which is sewn through the carcass ply and in contact with the chafer portion and a second seam portion which is in contact with the conductive portion.

According to this configuration, even when the volume resistivity of the carcass rubber in the carcass ply is relatively large and the conductivity of the carcass ply is low, the static electricity from the vehicle transmitted from the rim to the chafer portion can be transferred to the conductive portion via the sewn portion. As a result, the static electricity from the vehicle can be transferred to the tread portion via the conductive portion, and the static electricity can be released from the tread surface portion to the ground at the tread portion. Therefore, the static electricity from the vehicle can be more suitably released to the ground.

The volume resistivity of the conductive portion is smaller than the volume resistivity of the chafer portion.

According to this configuration, it is easy to suitably reduce the volume resistivity of the conductive portion. As a result, the static electricity can be suitably flown to the conductive portion that forms a relatively long conductive path from the bead portion to the tread portion. Therefore, the static electricity from the vehicle can be more easily released to the ground.

The conductive portion is a thread-like member containing metal, and may be a plurality of conductive portions provided at intervals along the tire circumferential direction.

According to this configuration, it is easy to reduce the volume resistivity of the conductive portion more suitably, and the static electricity is more easily flown from the bead portion to the tread portion by the conductive portion. Therefore, the static electricity from the vehicle can be more suitably released to the ground. Further, according to this configuration, the plurality of conductive portions are provided at intervals along the tire circumferential direction. Therefore, it is possible to increase the conductive path that allows the static electricity to flow from the bead portion to the tread portion, and the static electricity is more easily flown from the bead portion to the tread portion by the conductive portion. Therefore, the static electricity from the vehicle can be more suitably released to the ground.

The sewn portion may extend along the tire circumferential direction. According to this configuration, the sewn portion can easily cross the conductive portion, and the second seam portion in the sewn portion can be easily brought into contact with the conductive portion. In addition, one sewn portion can be easily brought into contact with the plurality of conductive portions.

The sewn portion may be in contact with a plurality of the conductive portions. According to this configuration, by providing one sewn portion, the plurality of conductive portions can be connected to the chafer portion, and it is possible to increase the conductive path that allows static electricity to flow from the bead portion to the tread portion. Therefore, the static electricity from the vehicle can be suitably released to the ground while reducing the time and effort required to provide the sewn portion.

The sewn portion may have a configuration in which at least one of the conductive portions is sewn into the carcass ply.

According to this configuration, the second seam portion can be more reliably brought into contact with the conductive portion.

The plurality of the sewn portions may be provided, and the plurality of sewn portions each may be in contact with the conductive portions that are different from each other.

According to this configuration, it is easy to reduce the region where the conductive thread is sewn in the carcass ply. As a result, the total amount of conductive threads required to form the sewn portion can be reduced. Therefore, a manufacturing cost of the tire can be reduced. In addition, an amount of work for sewing the conductive thread can be reduced.

Claim 1:
A tire (<NUM>, <NUM>) comprising:
a tread portion (<NUM>);
a sidewall portion (<NUM>);
a bead portion (<NUM>);
a bead core (<NUM>) provided in the bead portion (<NUM>); and
a carcass ply (<NUM>) covering at least a portion around the bead core (<NUM>),
wherein the carcass ply (<NUM>) includes a sewn portion (<NUM>, <NUM>) in which a conductive thread (<NUM>, <NUM>) is sewn,
wherein the tire (<NUM>, <NUM>) further comprises:
a conductive portion (<NUM>) extending along the carcass ply (<NUM>) and located outside the carcass ply (<NUM>) in a tire radial direction in the tread portion (<NUM>); and
a chafer portion (<NUM>) having conductivity and covering at least a portion around the carcass ply (<NUM>),
characterized in that
the sewn portion (<NUM>, <NUM>) is sewn through the carcass ply (<NUM>), and includes a first seam portion (80a) which is in contact with the chafer portion (<NUM>) and a second seam portion (80b) which is in contact with the conductive portion (<NUM>);
wherein a volume resistivity of the conductive portion (<NUM>) is smaller than a volume resistivity of the chafer portion (<NUM>).