TIRE WITH A CONDUCTIVE TREAD CHIMNEY COMPONENT

Abstract

Aspects of the invention relate to a tire that includes a shoulder wedge arranged in a shoulder portion of the tire between the sidewall and the belt package, the shoulder wedge being at least partially inserted between the belt package and the carcass ply. The tread includes a tread chimney component extending from the shoulder wedge to the rolling surface. The overlay coat of the tire's belt package, the tread band except for the tread chimney component, the tread base and the tire sidewall are made from non-conductive rubber. A conductive path between the rolling surface and the rim is provided across the tread chimney component, the shoulder wedge, the carcass ply and the chafer portion.

Claims

1. A tire, including: axially spaced apart annular bead cores; a carcass ply extending between the bead cores; a belt package arranged radially outwardly of the carcass ply, the belt package comprising an overlay coat; a tread disposed radially outwardly of the belt package, the tread comprising a tread band providing a radially outer rolling surface of the tire and a tread base adjacent the overlay coat; a sidewall overlying the carcass in a region between the belt package and one of the bead cores; a chafer portion adjacent to a radially inner portion of the sidewall and positioned around at least a portion of the bead core for contacting a rim; and a shoulder wedge arranged in a shoulder portion of the tire between the sidewall and the belt package, the shoulder wedge at least partially inserted between the belt package and the carcass ply; wherein the tread includes a tread chimney component extending from the shoulder wedge to the rolling surface, at least part of the tread chimney component extending across the tread band; wherein the overlay coat, the tread band except for the tread chimney component, the tread base and the sidewall are made from non-conductive rubber; and wherein a conductive path between the rolling surface and the rim is provided across the tread chimney component, the shoulder wedge, the carcass ply and the chafer portion.

2. The tire as claimed in claim 1, wherein the chafer portion includes a radially innermost toe guard and a chafer adjacent to the toe guard and to the sidewall.

3. The tire as claimed in claim 1, wherein both the toe guard and the chafer are made from conductive rubber.

4. The tire as claimed in claim 1, wherein the carcass ply includes a conductive ply coat extending at least from the shoulder wedge to the chafer portion.

5. The tire as claimed in claim 1, wherein the tread chimney component comprises a chimney base adjacent the overlay coat and a chimney extending across the tread band from the chimney base to the rolling surface.

6. The tire as claimed in claim 5, wherein the chimney is located substantially in an equatorial plane of the tire.

7. The tire as claimed in claim 5, wherein the chimney is located axially offset the equatorial plane of the tire.

8. The tire as claimed in claim 5, wherein the chimney base replaces the tread base between the chimney and the shoulder wedge.

9. The tire as claimed in claim 5, wherein the chimney base replaces part of a height of the tread base between the chimney and the shoulder wedge.

10. A tire, including: first and second axially spaced apart annular bead cores; a carcass ply extending between the first and second bead cores; a belt package arranged radially outwardly of the carcass ply, the belt package comprising an overlay coat; a tread disposed radially outwardly of the belt package, the tread comprising a tread band providing a radially outer rolling surface of the tire and a tread base adjacent the overlay coat; a first and a second sidewall overlying the carcass in a region between the belt package and the first and the second bead core, respectively; a first chafer portion adjacent to a radially inner portion of the first sidewall and positioned around at least a portion of the first bead core for contacting a rim; a second chafer portion adjacent to a radially inner portion of the second sidewall and positioned around at least a portion of the second bead core for contacting the rim; and a first shoulder wedge arranged in a first shoulder portion of the tire between the first sidewall and the belt package, the first shoulder wedge at least partially inserted between the belt package and the carcass ply; wherein the tread includes a tread chimney component extending from the first shoulder wedge to the rolling surface, at least part of the tread chimney component extending across the tread band; wherein the overlay coat, the tread band except for the tread chimney component, the tread base, and the first and second sidewalls are made from non-conductive rubber; and wherein a conductive path between the rolling surface and the rim is provided across the tread chimney component, the first shoulder wedge, the carcass ply and the first chafer portion.

11. The tire as claimed in claim 10, including a second shoulder wedge arranged in a second shoulder portion of the tire between the second sidewall and the belt package, the second shoulder wedge at least partially inserted between the belt package and the carcass ply.

12. The tire as claimed in claim 11, wherein the second shoulder wedge is made from non-conductive rubber.

13. The tire as claimed in claim 11, wherein a further conductive path between the rolling surface and the rim is provided across the tread chimney component, the second shoulder wedge, the carcass ply and the second chafer portion.

14. The tire as claimed in claim 10, wherein each of the first and second chafer portions includes a radially innermost toe guard and a chafer adjacent to the toe guard and to the first or second sidewall.

15. The tire as claimed in claim 10, wherein the carcass ply includes a conductive ply coat extending at least from the first shoulder wedge to the first chafer portion.

16. The tire as claimed in claim 10, wherein the tread chimney component comprises a chimney base adjacent the overlay coat and a chimney extending from the chimney base to the rolling surface, the chimney corresponding to the part of the tread chimney component that extends across the tread band.

17. The tire as claimed in claim 16, wherein the chimney is located substantially in an equatorial plane of the tire.

18. The tire as claimed in claim 16, wherein the chimney is located axially offset the equatorial plane of the tire.

19. The tire as claimed in claim 16, wherein the chimney base extends axially from the first shoulder wedge to the chimney without extending axially beyond the chimney.

20. The tire as claimed in claim 13, wherein the tread chimney component comprises a chimney base adjacent the overlay coat and a chimney extending across the tread band from the chimney base to the rolling surface and wherein the chimney base extends axially from the first shoulder wedge to the second shoulder wedge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention will be described by way of example and with reference to the accompanying drawings in which:

[0054] FIG. 1 is a cross sectional view of a tire according to an embodiment of the invention, cut along a meridian plane thereof;

[0055] FIG. 2 is a cross sectional view of a variant of the tire of FIG. 1;

[0056] FIG. 3 is a cross sectional view of a tire according to a further embodiment of the invention, cut along a meridian plane thereof; and

[0057] FIG. 4 is a cross sectional view of a variant of the tire of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0058] A first embodiment of a pneumatic ultra-low rolling resistance (ULRR) tire in accordance with an embodiment of the invention is illustrated in FIG. 1. Pneumatic tire 10 includes a pair of bead cores 12, which serve to secure the tire 10 to a wheel. The tire 10 further includes a carcass ply 14, which extends between the bead cores 12 so as to confer the tire its generally toroidal shape. The carcass ply 14 is wrapped around the bead cores 12 and terminates in respective turnup portions 16 arranged adjacent the main toroidal portion of the carcass ply 12. Annular apexes 18 arranged in the radially inner sidewall portion, between the bead cores 12, the turnup portions 16 and the main portion of the carcass ply 14 serve as fillers to provide progressive transition from the rather stiff bead portion into the more flexible sidewall portion. A tread 20 is formed in the radially outer part of the tire 10. The tread 20 is formed of a tread band 22, comprising one or more tread layers 22a, 22b and tread base 23 and rests on a belt package 24, which provides stability to the tread 20 and prevents cuts or perforations in the tread band 22 from reaching the carcass ply 14. The belt package 24 comprises an overlay coat 25 adjacent to the tread base 23.

[0059] The zones in which the tread portion and the sidewall portions meet are generally referred to as the shoulder portions 26 of the tire 10. In each shoulder portion 26, the tire 10 comprises a respective shoulder wedge 28 resting on the carcass ply 14 and serving as a support for the axially outer end of the belt package 24 and the axially outer extremity of the tread band 22.

[0060] In the sidewall portions of the tire 10, the axially outer sides of the carcass ply 14 are covered with the sidewalls 30. The sidewalls 30 protect the carcass ply 14, and together with the carcass ply define the flexing behavior of the tire, and withstand weathering. On the radially inward side, the sidewalls 30 connect to the chafer portions 32. The chafer portions 32 include each a radially innermost toe guard 34 and a chafer 36.

[0061] The interior of the tire 10 is lined with an innerliner 38.

[0062] To reduce the rolling resistance of tires, rubber mixes traditionally used in the tire carcass and the tread need to be replaced by less hysteric rubbers. A way to achieve this is to reduce the carbon black content of the rubbers and to use other reinforcement agents, such as, e.g., silica. However, rubbers suitable to achieve the desired lowest rolling resistance, e.g., rolling resistance class A according to EU Regulation 2020/740, i.e., a rolling resistance coefficient (RRC)≤6.5 N/kN for C1 tires (tires for cars), ≤5.5 N/kN for C2 tires (tires for vans) or ≤4.0 N/kN for C3 tires (tires for heavy-duty vehicles), are non-conductive. Accordingly, tires exhibiting good performance in terms of rolling resistance are currently considered as challenging in terms of electrical conductivity, which is needed in practice to prevent charge build-up between ground and the vehicle.

[0063] In the ULRR tire of FIG. 1 at least the tread band 22, the tread base 23, the overlay coat 25 and the sidewall comprise non-conductive rubber. The shoulder wedges 28, the carcass ply 14 and the chafer portion 32 (including toe guard 34 and chafer 36) contain conductive rubber. A tread chimney component 40 comprising conductive rubber is arranged to extend from the one of the shoulder wedges 28 to the rolling surface. The chimney component 40 extends annularly around the tire. A part of the tread chimney component, the chimney 42, extends across the tread band 22. In the illustrated embodiment, the chimney 42 has generally the shape of the frustrum of a cone. If the cone's aperture angle is about 180°, the chimney 42 takes generally the shape of an annulus. The chimney is connected to a further part of the tread chimney component, the chimney base 44, which is arranged adjacent the overlay coat so as to replace the tread base 23 on an axial extent. The chimney base 44 is connected to the shoulder wedge 28. A conductive path is thus formed from the tread surface to the toe guard 34. The conductive path comprises the chimney 42, the chimney base 44, the shoulder wedge 28, the carcass ply 14, the chafer 36 and the toe guard 34.

[0064] FIG. 2 illustrates a variant of the embodiment of FIG. 1, which may be advantageous if the carcass ply 14 is not sufficiently conductive by itself. In this case, a ply coat 46 comprising conductive rubber and extending at least from the shoulder wedge 28 to the chafer portion 32 may be provided. Such conductive ply coat 46 is arranged electrically in parallel with the carcass ply 14, which efficiently reduces electrical resistance in the sidewall portion of the tire. Apart from that difference, the tire of FIG. 2 is identical to the tire of FIG. 1 and the reader may refer to the description above of the embodiment shown FIG. 1. In addition to a ply coat 46 comprising conductive rubber or as an alternative thereto, gas bleeder cords also functioning to conduct electrical charge from the shoulder wedge 28 to the chafer portion 32 (electrically conducting bleeder cords) may be provided.

[0065] FIG. 3 illustrates a further embodiment of an ULRR pneumatic tire 110 in accordance with aspects of the invention. Pneumatic tire 110 includes first and second axially spaced bead cores 112. A carcass ply 114 extends between the first and second bead cores 112 so as to confer the tire 110 its generally toroidal shape. Carcass ply 114 terminates in first and second turnup portions 116 wrapped around the first and second bead cores 112, respectively. First and second apexes 118 are arranged in the radially inner sidewall portion, between the respective bead core 112, the respective turnup portion 116 and the respective main portion of the carcass ply 114. A tread 120 is formed in the radially outer part of the tire 110. The tread 120 comprises a tread band 122, itself comprising one or more tread layers 122a, 122b and a tread base 123. The tread 120 is supported on its radially inner side by a belt package 124. The belt package 124 comprises an overlay coat 125 adjacent to the tread base 123.

[0066] In the first and second shoulder portions 126 of the tire 110, a first and a second shoulder wedges 128 are provided. First and second shoulder wedges 128 are supported by the carcass ply 114 and serve as supports for the axially outer ends of the belt package 124 and the axially outer extremities of the tread band 122.

[0067] In the sidewall portions of the tire 110, the axially outer sides of the carcass ply 114 are covered with first and second sidewalls 130. On their radially inward sides, the first and second sidewalls 130 connect to first and second chafer portions 32, respectively. Each chafer portion 132 includes each a radially innermost toe guard 134 and a chafer 136. The interior of the tire 110 is lined with an innerliner 138.

[0068] At least the tread band 122, the tread base 123, the overlay coat 125 and the sidewalls 130 comprise non-conductive rubber mixes. The shoulder wedges 128, the carcass ply 114 and the chafer portions 132 (including toe guards 134 and chafers 136) contain conductive rubber. A tread chimney component 140 comprising conductive rubber is arranged to extend from the first and/or the second shoulder wedge 128 to the rolling surface. The chimney component 140 extends annularly around the tire 110. A part of the tread chimney component 140, the chimney 142, extends across the tread band 122. In the illustrated embodiment, the chimney 42 has generally the shape of a flat annulus (like a washer) arranged essentially in the equatorial plane of the tire 110. The chimney 142 connects to another part of the tread chimney component 140, the chimney base 144, which is arranged adjacent the overlay coat so as to replace the tread base 123 in part of its height throughout an axial extent from the chimney 142 to the first axial end of the tread base 123. The chimney base 144 is connected to one of the shoulder wedges 128. A conductive path, which comprises the chimney 142, the chimney base 144, the first shoulder wedge 128, the carcass ply 114 and the first chafer portion 132 (including chafer 136 and toe guard 134) is thus formed from the tread surface to the toe guard 134.

[0069] FIG. 4 illustrates a variant of the embodiment of FIG. 3. In the variant of FIG. 4, the chimney base 142 extends from the first shoulder wedge to the second shoulder wedge, adjacent a tread base 123 of reduced thickness (height). According to the variant illustrated in FIG. 4, a first and a second conductive paths are provided between the tread surface and the toe guard 134 and have the chimney 142 in common. The first conductive path is as described with reference to FIG. 3, while the second conductive path comprises the chimney 142, the (other side of) the chimney base 144, the second shoulder wedge 128, the carcass ply 114 and the second chafer portion 132 (including chafer 136 and toe guard 134).

[0070] Although FIGS. 3 and 4 show the chimney 142 to be located in the equatorial plane of the tire 110, it may also be located axially offset therefrom. As in the embodiment discussed with reference to FIG. 1, the carcass ply could be arranged to include a conductive ply coat extending at least from the first and/or the second shoulder wedge to the first and/or the second chafer portion, respectively, to decrease electrical resistance across the first and/or second conductive path.

[0071] Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.