Patent Description:
Tyres having noise-supressing characteristics are known e.g. from the document <CIT>. As shown therein, to supress noise sound-absorbing material is provided to an interior of a tyre.

As shown in <FIG> and <FIG> of that document a band-like noise suppressing body extends in the tyre circumferential direction on an inner side of a tyre. The ends of the band may be separated from each other; or the ends may be integrally connected to each other by adhesive.

It has been found that to improve the sound-supressing properties of the tyre, preferably one should rather use more sound-absorbing material than less. Thus, the gap(s) (if any) in between the ends of the band-like element(s) should only be narrow.

As discussed above, if the ends of the band are connected to each other, they are connected by using adhesive. This reduces the problem of the sound-absorbing material wearing in use.

However, it has been found that joining the ends of the band-like element(s) together with adhesive requires a lot of manual work and still oftentimes the band-like element(s) tend to detach from the tyre in use.

Therefore, there is a need for a such a method that a band-like element (hereinafter a ribbon) can be attached to the inner surface of a tyre in a reliable manner so that no gaps or only a narrow gap is arranged between the ends of the ribbon. There is also a need for a tyre, wherein the ribbon is attached in a reliable manner so that no gaps or only a narrow gap is arranged between the ends of the ribbon. Moreover, in line with the prior art, the wear of the sound absorbing material in such a solution should be diminished. Finally, the noise-absorbing material should be applied in such a way that the mass of the tyre is balanced about the rotational axis.

In this field, in the publication <CIT> a sound damper (<NUM>) is formed by affixing foam material to a tire inner cavity surface to form a ring shape, with the other surface of the foam material being toward an outer circumference, and end faces of the foam material in the longitudinal direction abut each other and are bonded. The document <CIT> discloses a pneumatic tire to be attached to a rim, provided with a noise damper made of a spongy material. Noise dampers having the same cross-sectional shape are used in a size group of pneumatic tires which include a minimum volume tire and a maximum volume tire.

It has been found that the detachment problems of the ribbon are related to the ends of the ribbon compressing each other particularly on the side closer to the rotational axis of the tyre.

To this end, it has been found that by using such a ribbon, of which shape tapers towards an end of the ribbon so that its local thickness decreases towards the end of the ribbon, the ends of the ribbon on the inner side of the ribbon do not compress each other, which seemingly overcomes the problem. Moreover, at the same time, to have a lot a noise-supressing material, at least a part of the second end of the ribbon is compressed against the first end of the ribbon.

Moreover, even if the noise-absorbing material of the ribbon is generally lightweight no gap at all generally implies a better mass-balance than a wide gap; unless compensated by other gaps, which however, would imply decreasing the amount of the noise-absorbing material.

Finally, it has been found that the tapering shape of at least one end of the ribbon has the effects that a contact area (if any) of the ends of the ribbon remain small, which decreases the problem of the sound-absorbing material wearing in use.

The method and the tyre according to the invention is disclosed more specifically in the independent claims.

In a preferably embodiment, the shape of the ribbon tapers towards an end of the ribbon so that an angle of inclination is approximately <NUM> degrees (<NUM> to <NUM> degrees, e.g. <NUM> to <NUM> degrees). This, on one hand relieves the compressive stress from the ends of the ribbon, and on the other hand ensures that a significant portion of the ribbon is non-tapering, which implies a reasonably high amount of the noise-suppressing material; and also implies a reasonably good mass balance.

In a preferably embodiment, the shape of the ribbon tapers towards only one end of the ribbon. Also this ensures that a significant portion of the ribbon is non-tapering, which implies a reasonably high amount of the noise-suppressing material; and also implies a reasonably good mass balance.

<FIG> shows in a perspective view a tyre <NUM>. The tyre <NUM> is tubeless pneumatic tyre. The tyre <NUM> is tubeless pneumatic tyre intended for use as a tyre of a passenger car in regular road use. The tyre <NUM> comprises an inner surface <NUM>, which is opposite to an outer surface <NUM> of the tyre <NUM>. The tyre <NUM> comprises a tread <NUM> on its outer surface <NUM>. The tread <NUM> has circumferential and transversal grooves, said grooves defining a number of tread blocks. The tread <NUM> is meant for a rolling contact against a ground surface <NUM>, such as the road. The grooves are meant for draining water and/or slush that is possibly located on the ground surface away from the tread <NUM>, so that the contact between the tread <NUM> and the ground surface <NUM> is as good and consistent as possible. Studs may be provided on the tread <NUM>. The tyre <NUM> has a tubular shape, which defines an axis of rotation AX for the tyre <NUM>. In use, the tyre <NUM> in configured to rotate about the axis of rotation AX.

In order to reduce the noise generated by the tyre <NUM> in use, the tyre <NUM> comprises sound-absorbing material on an inner side of the tyre <NUM>. The sound-absorbing material is formed as a ribbon <NUM> and attached to a body <NUM> of the tyre <NUM>. Thus, the ribbon <NUM> comprises the sound-absorbing material. With reference to <FIG>, the ribbon <NUM> is attached on the inner side of the body <NUM> of the tyre, particularly opposite to the tread <NUM>, in such a way that a first main surface <NUM> of the ribbon <NUM> faces the axis AX of rotation of the tyre. The whole ribbon <NUM> needs not be opposite the tread <NUM>; instead, the ribbon <NUM> may be e.g. wider than the tread <NUM>. However, at least a part of the ribbon <NUM> is arranged opposite the tread <NUM>. Typically, the first main surface <NUM> of the ribbon <NUM> forms a part of the inner surface <NUM> of the tyre <NUM>. However, if needed, the ribbon <NUM> could be coated by some other material forming the inner surface <NUM>. Thus, in an embodiment, the first main surface <NUM> of the ribbon <NUM> or a coating thereof forms a part of the inner surface <NUM> of the tyre <NUM>.

As detailed below, the tyre <NUM> (e.g. of <FIG> or <FIG>) has been manufactured by attaching a solid ribbon <NUM> of the sound-absorbing material on an inner side of a body <NUM> (e.g. of <FIG>) of the tyre <NUM>. Such a solid ribbon <NUM> comprises a first end <NUM> and a second end <NUM> (see <FIG>, and <FIG>). Therefore, also in the tyre <NUM>, the ribbon <NUM> comprises a first end <NUM> and a second end <NUM> as detailed in <FIG>, <FIG>, and <FIG>. Referring to <FIG>, a seam <NUM> remains in between the first end <NUM> and the second end <NUM>. In <FIG>, wherein the ends <NUM>, <NUM> are in contact with each other, the seam <NUM> is arranged in between them. In <FIG>, not according to the claimed invention, the ends <NUM>, <NUM> are not in contact with each other, the gap G is arranged in between them. Moreover, the ribbon <NUM> extends from the first end <NUM> of the ribbon <NUM> to the second end <NUM> of the ribbon <NUM>. In particular, the ribbon <NUM> extends from the first end <NUM> of the ribbon <NUM> to the second end <NUM> of the ribbon <NUM> such that only one seam is arranged in between the first end <NUM> and the second end <NUM>.

As shown in <FIG>, <FIG>, the first end <NUM> of the ribbon <NUM> is in contact with the second end <NUM> of the ribbon <NUM>. This has the effect that a lot of sound-absorbing material can be arranged on the inner side of the tyre <NUM>, because, by definition, a gap would be free from sound-absorbing material. This improves the sound-absorbing properties of the tyre <NUM>. In these embodiments, a seam is arranged between the ends <NUM>, <NUM> of the ribbon <NUM>.

As shown in <FIG> and <FIG>, not according to the claimed invention, in an tyre, a gap G is arranged between the first end <NUM> of the ribbon <NUM> and the second end <NUM> of the ribbon <NUM>. However, to improve the sound-absorbing properties of the tyre <NUM>, a maximum width Wg of the gap G is small. Herein the maximum width Wg of the gap G is defined (i.e. measured) along the body <NUM> of the tyre <NUM>. The maximum width Wg of the gap G is defined (i.e. measured) in the circumferential direction SC of the tyre <NUM>. The maximum width Wg of the gap G is at most <NUM>. Moreover, the body <NUM> of the tyre <NUM> refers to the part of the tyre <NUM> to which the ribbon <NUM> is attached. The body <NUM> of the tyre <NUM> may comprise all other parts of the tyre <NUM> than the ribbon <NUM>.

As shown in <FIG> and <FIG>, in the claimed invention, the seam <NUM> widens towards the rotational axis AX of the tyre <NUM>.

However, to increase the amount of sound-absorbing material, preferably the first end <NUM> of the ribbon <NUM> is in contact with the second end <NUM> of the ribbon <NUM> (see <FIG>).

As indicated in <FIG> and <FIG>, and <FIG>, the shape of the ribbon <NUM> tapers such that a thickness Tr of the ribbon <NUM> decreases towards the second end <NUM> of the ribbon <NUM>. This has the effect that on the side of the axis of rotation AX, i.e. on the side of the first main surface <NUM>, the ends <NUM>, <NUM> of the ribbon <NUM> do not compress each other. Therefore, even if there is a lot of sound-absorbing material in the tyre (as evidence by no gap), the ends <NUM>, <NUM> of the ribbon do not compress each other on the side of the axis of rotation AX, which improves the attachment of the ribbon <NUM> to the tyre <NUM> and also reduces the ends <NUM>, <NUM> of the ribbon <NUM> grinding each other.

<FIG> shows a quarter of a cross-section of a tyre <NUM>. It also shows a radial direction SR (see <FIG>) and an axial direction SAX, which is parallel to the axis of rotation AX. A tubeless pneumatic tyre <NUM> for a vehicle comprises multiple components. A tyre <NUM> typically comprises an innerliner <NUM>. Innerliner <NUM> refers to a layer or layers of rubber or rubber-based components. Thus, a function of the innerliner <NUM> is to resist air or gas diffusion, or, in other words, decrease air or gas permeability of the tyre <NUM>.

Thus, in a preferable embodiment, the tyre comprises an innerliner <NUM>. The innerliner may comprise butyl-rubber, such as halobutyl rubber, in particular bromobutyl rubber and/or chlorobutyl rubber. The innerliner <NUM> or a coating thereof may form a part of the inner surface <NUM> of the tyre <NUM>.

The tyre <NUM>, in particular the body <NUM> thereof, comprises a reinforcement <NUM>. The reinforcement <NUM> comprises at least a first ply <NUM> and a first metal belt <NUM>. Preferably, the reinforcement <NUM> further comprises a textile belt <NUM>, such as a textile belt <NUM> comprising fibrous polyamide (e.g. Nylon, aramid, or Cordura). Preferably, the reinforcement <NUM> further comprises the textile belt <NUM>, a second ply <NUM> and a second metal belt <NUM>. The metal belt(s) <NUM>, <NUM> is/are resilient metal belts, such as steel belts comprising wires. The ply/plies <NUM>, <NUM> may comprise fibrous material, e.g. Kevlar, polyamide, carbon fibres, or glass fibres. The tread <NUM> comprises tread blocks made of rubber material; and it may comprise also other objects such as studs.

In addition to tread area components, the pneumatic tyre <NUM> (and the body <NUM> thereof) comprises a sidewall <NUM>. The sidewall is typically configured to withstand flexing. A bead area of the tyre <NUM> may comprise, for example bead base <NUM> configured to seat to a rim, thereby enabling a tight sealing of the tyre <NUM> with the wheelrim. A bead cable <NUM>, typically comprising metal, helps seating the bead base <NUM> to the rim.

The tyre <NUM> can be manufactured by attaching a ribbon <NUM> to a body <NUM> for a tyre <NUM>. Thus, a method for manufacturing the tyre <NUM> comprises receiving the body <NUM> for the tyre <NUM>. The body <NUM> for the tyre <NUM> comprises an inner surface <NUM> opposite an outer surface <NUM>. The body <NUM> also comprises the tread <NUM>, which is provided on a part of the outer surface <NUM>. The body <NUM> for the tyre <NUM> may comprise other parts of the tyre <NUM> than the ribbon <NUM> and the tape or adhesive (<NUM>, <NUM>) that is used to attach the ribbon <NUM> to the body <NUM>. Thus, what has been said about the structure of the tyre <NUM> applies to the body <NUM> mutatis mutandis.

The body <NUM> for the tyre <NUM> may be manufactured in the way tyres without sound-absorbing material are conventionally manufactured. Examples can be found e.g. from the publication <CIT> and references cited therein. Thus, the body <NUM> can be manufactured. In the alternative, the body <NUM> may be bought. In either case, the body <NUM> is provided; e.g. received. The body <NUM> for the tyre <NUM> comprises rubber.

The method comprises manufacturing a ribbon <NUM> from sound-absorbing material. The sound-absorbing material is physically or chemically different from the material of the body <NUM> for the tyre <NUM>. The sound-absorbing material may be e.g. provided as a long band on a reel, and the ribbon <NUM> can be cut from the band.

In general, a sound-absorbing material may have a low density. In an embodiment, a density of the material of the ribbon <NUM> is less than a density of the body <NUM> for the tyre. In an embodiment, a density of the material of the ribbon <NUM> is less than <NUM>/m<NUM>. The density may be more than <NUM>/m<NUM>. The sound-absorbing material may be reasonably soft. The hardness of the material is preferably from <NUM> N to <NUM> N, such as <NUM> to <NUM> N. The hardness herein refers to the hardness as defined in the standard ISO <NUM> (<NUM>th ed <NUM>-<NUM>-<NUM>), method B, and for the indentation <NUM> % (see section <NUM>. d to <NUM>.

In an embodiment the ribbon <NUM> comprises polymeric foam. Preferably, the ribbon <NUM> comprises polymeric foam; more preferably, the ribbon <NUM> consists of polymeric foam.

A matrix material of the polymeric foam is preferably selected from the group of ethylene-vinyl-acetate, polyethylene (such as LDPE and HDPE), nitrile rubber, polychloroprene, neoprene, polyimide, polypropylene (such as expanded polypropylene and polypropylene paper), polystyrene (such as expanded polystyrene, extruded polystyrene, Styrofoam, and polystyrene paper), polyurethane (such as low-resilience polyurethane, memory foam, and sorbothane), polyvinyl chloride, and silicone.

Other materials having a low density and that are suitable for use as the sound-absorbing material include aerogels, such as silica aerogels or carbon nanotube aerogels, aero graphite, metallic foams, and metallic micro lattices. Such materials that as such are hard and/or brittle may be used e.g. in the form of grains arranged in a bendable matrix material.

What has been said about the material of the ribbon <NUM> as such applies also to the tyre <NUM>, of which part the ribbon <NUM> forms.

As for the shape of the ribbon <NUM> as such, i.e. in the context of the method, reference is made to <FIG>. The ribbon <NUM> comprises a first main surface <NUM> and a second main surface <NUM>. The second main surface <NUM> is opposite the first main surface <NUM>. The ribbon <NUM> also comprises the first end <NUM> and the second end <NUM>, which is opposite the first end <NUM>.

As for the dimensions of the ribbon <NUM>, the ribbon <NUM> has a length Lr, a width Wr, and a thickness Tr. These dimensions are defined in certain directions, which are mutually perpendicular, as usually. The thickness Tr is smaller than the length Lr. The width Wr is smaller than the length Lr. Normally, the thickness Tr is smaller than the width Wr. The thickness Tr is defined in a direction Dt of the thickness Tr.

The first and second main surfaces <NUM>, <NUM> are defined so that the direction Dt of the thickness Tr is normal to at least a part of the first main surface <NUM>. Moreover, the direction Dt of the thickness Tr is normal to the second main surface <NUM>.

To reduce the compression of the ends of the ribbon <NUM> at an inner side of the ribbon (as discussed above in context of the tyre), the shape of the ribbon <NUM> is such that the ribbon <NUM> tapers towards the second end <NUM> of the ribbon in the direction Dt of the thickness Tr, as shown in <FIG>. Referring to <FIG>, in an embodiment, the shape of the ribbon <NUM> is such that the ribbon <NUM> does not taper towards the second end <NUM> of the ribbon in a direction of the width Wr. in an embodiment, the width Wr is constant. However, the shape of the second main surface <NUM> need not be rectangular. Thus, in an embodiment, only a thickness of the ribbon reduces towards the second end <NUM>.

The method comprises attaching the second main surface <NUM> of the ribbon <NUM> on the inner surface <NUM> of the body <NUM> for the tyre <NUM>. Referring to <FIG>, the second main surface <NUM> is attached in such a way that a central line CL of the ribbon <NUM> that is parallel to a direction DI of the length Lr of the ribbon <NUM> becomes parallel to a circumferential direction SC of the body <NUM> for the tyre <NUM>.

Moreover, referring to <FIG>, in an embodiment, the second main surface <NUM> is attached in such a way that the first end <NUM> of the ribbon is in contact with the second end <NUM> of the ribbon <NUM>. Thus, a seam <NUM> is formed between the ends <NUM>, <NUM> of the ribbon.

In addition or alternatively, referring to <FIG>, in a tyre not according the invention, the second main surface <NUM> is attached in such a way that a gap G is arranged between the first end <NUM> of the ribbon <NUM> and the second end <NUM> of the ribbon <NUM>. Even if the ends <NUM>, <NUM> need not be in contact with each other, a maximum width Wg of the gap is at most <NUM>. As detailed in the context of the tyre, the maximum width Wg is measured along the inner surface <NUM> of the body <NUM> of the tyre <NUM>. Moreover, the maximum width Wg is measured in the circumferential direction SC.

As readable from above, the ribbon <NUM> (unless covered by some material) forms a part of the inner surface of the tyre. However, because the body <NUM> does not comprise the ribbon <NUM>, the inner surface of the body <NUM> is not formed by the ribbon <NUM>. Moreover, in the method, before the tyre has been manufactured, the body <NUM> can be considered as being a body for the tyre. However, after the tyre has been made, that part can be considered as being a body of the tyre.

A length Lr of the ribbon <NUM> may be substantially equal to the circumference of the inner surface <NUM> of the body <NUM> for the tyre. First, these lengths may be equal. When these lengths are equal, the first end <NUM> of the ribbon contacts the second end <NUM> of the ribbon, whereby no gap is formed, at least not on the side of the second main surface <NUM> of the ribbon, as shown in <FIG> and <FIG>. However, with reference to <FIG> and <FIG> the seam widens towards the axis of rotation AX. Moreover, because the length of the ribbon equals the circumference, the ribbon <NUM> needs not be pressed, whereby both the ends <NUM>, <NUM> of the ribbon have substantially the same shape when part of the tyre <NUM> as when not part thereof. In such an embodiment, the second end <NUM> of the ribbon is not compressed against the first end <NUM> of the ribbon.

Second, a length Lr of the ribbon <NUM> may be slightly more than the circumference of the inner surface <NUM> of the body <NUM> for the tyre. Also in this case the first end <NUM> of the ribbon contacts the second end <NUM> of the ribbon, whereby no gap is formed, at least not on the side of the second main surface <NUM> of the ribbon, as shown in <FIG> and <FIG>. However, with reference to <FIG> and <FIG> the seam widens towards the axis of rotation AX. Moreover, because of the difference in the lengths, the ends <NUM>, <NUM> are being pressed to each other. In such an embodiment, at least a part of the second end <NUM> of the ribbon is compressed against the first end <NUM> of the ribbon. A corresponding embodiment of the method comprises compressing at least a part of the second end <NUM> of the ribbon against the first end <NUM> of the ribbon when attaching the ribbon to the body <NUM> of the tyre <NUM>. For example, the length Lr of the ribbon <NUM> may be greater than a circumference of the body <NUM> for the tyre <NUM>. The circumference of the body <NUM> for the tyre <NUM> is defined on a central line of the inner surface <NUM> of the body <NUM> for the tyre <NUM>. For example, the length Lr of the ribbon may be <NUM> to <NUM> greater than the circumference of the body for the tyre <NUM>.

Even if there is a seam between the ends <NUM>, <NUM> of the ribbon <NUM>, as in <FIG>, preferably, the first end <NUM> of the ribbon <NUM> is not attached directly to the second end <NUM> of the ribbon <NUM> with adhesive or tape. Naturally both the ends <NUM>, <NUM> are attached to the body <NUM> of the tyre <NUM>. Correspondingly, preferably, [a] neither adhesive nor tape is arranged between the first end <NUM> of the ribbon <NUM> and the second end <NUM> of the ribbon <NUM> (as in <FIG>) or [b] adhesive or tape is arranged between the first end <NUM> of the ribbon <NUM> and the second end <NUM> of the ribbon <NUM> only on the inner surface of the body <NUM> of the tyre (as the case may be in <FIG>).

In particular, in an embodiment, the ribbon <NUM> comprises a first end surface <NUM> and a second end surface <NUM>, and neither adhesive not tape is provided on either of the first end surface <NUM> and the second end surface <NUM>. These end surfaces <NUM>, <NUM> will be defined in more detail later. Having these end surfaces <NUM>, <NUM> free of adhesive and tape has the benefit that the tyre <NUM> is easier to manufacture. It suffices to provide adhesive or tape on one of: [i] the inner surface <NUM> of the body <NUM> for the tyre or [ii] the first main surface <NUM> of the ribbon <NUM>. Such a process can be automated much more easily than one wherein adhesive is provided also on an end surface <NUM>, <NUM> to join the end surfaces together.

An embodiment of the method comprises attaching the second main surface <NUM> of the ribbon <NUM> to the inner surface <NUM> of the body <NUM> for the tyre using adhesive <NUM> and/or tape <NUM>, such as double-sided tape. A tyre <NUM> made in such a way comprises adhesive <NUM> and/or tape <NUM>, by which the ribbon <NUM> has been attached to the body <NUM> of the tyre <NUM>. A tape comprises carrier material and adhesive on at least one side of the carrier. Double-sided tape comprises the carrier material and adhesive on both sides of the carrier. The adhesive or the tape made be applied in the form of stripes. Such stripes may extend e.g. on an inner surface <NUM> of the body <NUM> for the tire in the circumferential direction SC. Such stripes may extend e.g. on the second main surface <NUM> of the ribbon in the longitudinal direction DI.

Referring to <FIG>, in an embodiment, the ribbon <NUM> does not taper towards the first end <NUM>. Thus, in an embodiment, the shape of the ribbon <NUM> is non-tapering towards the first end <NUM> of the ribbon <NUM>. In other words, in this embodiment, the thickness of the ribbon does not decrease towards the first end <NUM>. Moreover, in this embodiment, the width of the ribbon does not decrease towards the first end <NUM>.

Referring to <FIG>, the shape of the first end <NUM> of the ribbon <NUM> defines a first angle of inclination α'. The first angle of inclination α' may be e.g. <NUM> degrees, e.g. in the case the first end <NUM> is not tapering. However, as shown in <FIG>, in an embodiment, the shape of the ribbon <NUM> is tapering also towards the first end <NUM> of the ribbon <NUM>. In such a case, the first angle of inclination α' is less than <NUM> degrees. Preferably, the first angle of inclination α' is at least <NUM> degrees, more preferably at least <NUM> degrees, such as <NUM> degrees. The first angle of inclination α' herein refers to a minimum angle between the two planes defined by the first end surface <NUM> (which preferably is planar) and the second main surface <NUM> (which preferably is planar).

Referring to <FIG>, because the ribbon <NUM> tapers at least towards the second end <NUM>, a second angle of inclination β' is formed at the second end <NUM>. The second angle of inclination β' is less than <NUM> degrees and may be e.g. at most <NUM> degrees. Preferably, the second angle of inclination β' is <NUM> to <NUM> degrees, e.g. about <NUM> degrees, such as <NUM> to <NUM> degrees. The second angle of inclination β' herein refers to a minimum angle between the two planes defined by the second end surface <NUM> (which preferably is planar) and the second main surface <NUM> (which preferably is planar).

Referring to <FIG>, it is noted that in the tire <NUM> the seam <NUM> extends from one side of the ribbon <NUM> to another, opposite side of the ribbon <NUM>, and it/they extend/extends in a first direction Ds in this way. Within this description the term "direction" refers to two directions that are reverse to each other.

Most preferably, the first direction Ds is parallel to an axial direction SAX of the tyre <NUM> as in <FIG>. The axial direction SAX is a direction that is parallel to the axis of rotation AX. The first direction Ds need not be parallel to an axial direction SAX, as in <FIG>. However, in an embodiment, the first direction Ds or forms a third minimum angle δ of at most <NUM> degrees with the axial direction SAX of the tyre <NUM>. The term "minimum angle" is used, because, when a direction refers to two reverse directions, two directions form four angles, of which at most two are different, and the smaller of these is referred to here, unless there is only the one straight angle, which then is the minimum angle. This applies to also other angles that will be discussed.

When the first direction Ds is parallel to an axial direction SAX of the tyre <NUM>, in the method, the second main surface <NUM> is rectangular. In the context of the method, this is preferable. Reference is made to <FIG>. However, since the third minimum angle δ needs not be zero, the second main surface <NUM> needs not be rectangular, as readable from in <FIG> (note that the second main surface <NUM> remains opposite the first main surface <NUM> shown in <FIG>). In an embodiment of the method, the second main surface <NUM> of the ribbon is quadrangular such that each angle is <NUM> to <NUM> degrees (in line with the third minimum angle δ). As readable from <FIG>, when the third minimum angle δ is not zero, a third normal M1 (see <FIG>) is not parallel to the direction DI of length (as evidenced by the fourth minimum angle ϕ), even if the first angle of inclination α' is <NUM> degrees.

A small third minimum angle δ (e.g. zero) has the effect that the seam remains short, whereby the inclined second end <NUM> takes up less space that in case the third minimum angle δ would be larger. Thus, this is beneficial from the point of view of suppressing noise of the tyre. <FIG> shows an embodiment, wherein the third minimum angle δ is small but not zero, and <FIG> shows a preferable embodiment, wherein the third minimum angle δ is zero.

The first angle of inclination α' and the second angle of inclination β' relate to some other angles, too, observable from the tyre <NUM> and/or the ribbon <NUM>.

Concerning first the tyre <NUM> and with reference to <FIG> (and <FIG> and 2a) the first end <NUM> of the ribbon <NUM> having the first angle of inclination α' also has a first end surface <NUM>. Thus, in an embodiment, the ribbon <NUM> (as such or as part of the tyre <NUM>) comprises a first end surface <NUM> at the first end <NUM>. In a similar way the second end <NUM> of the ribbon <NUM> having the second angle of inclination β' also has a second end surface <NUM>. Thus, in an embodiment, the ribbon <NUM> (as such or as part of the tyre <NUM>) comprises a second end surface <NUM> at the first end <NUM>. In the embodiments of <FIG> the ribbon <NUM> comprises such first and second end surfaces, even if not shown in those figures by a reference numeral.

Referring to <FIG>, in an embodiment, a first normal N1 of the whole first end surface <NUM> is perpendicular to a radial direction SR of the tyre at the location of the first normal N1. In other words, the in an embodiment, a first normal N1 the whole first end surface <NUM> is parallel to a circumferential direction SC of the tyre at the location of the first normal N1 (i.e. at a location of the body <NUM> of the tire, the location of the body <NUM> being arranged on a same radial line as the point at which the first normal N1 is defined). Herein the term parallel covers the options of being unidirectional or being reverse.

In <FIG>, the first normal N1 is normal to the whole first end surface <NUM>, because the first end surface <NUM> is planar. In a preferable embodiment, the first end surface <NUM> is planar. This is beneficial from manufacturing point of view, because then the ribbon <NUM> can simply be cut from a band. However, only a part of the first end surface <NUM> may be planar. Moreover, the first end surface <NUM> needs not be planar. Thus, in an embodiment, a first normal N1 of a part of the first end surface <NUM> is perpendicular to a radial direction SR of the tyre at the location of the first normal N1. In other words, in an embodiment, a first normal N1 of a part of the first end surface <NUM> is parallel to a circumferential direction SC of the tyre at the location of the first normal N1.

However, as detailed above, the first angle of inclination α' need not be <NUM> degrees (see e.g. <FIG>), whereby the first normal N1 needs not be parallel to the circumferential direction SC or perpendicular to the radial direction SR.

In an embodiment, a first normal N1 of the whole first end surface <NUM> or a part of the first end surface <NUM> forms a first minimum angle α of at least <NUM> degrees, preferably at least <NUM> degrees, most preferably at least <NUM> degrees, with a radial direction SR of the tyre. Herein the radial direction is defined at that location (or radially outward, as indicated above). Reference is made to <FIG>. The term minimum angle is used, because both the first normal N1 and the radial direction SR are considered to be definable in two opposite directions resulting at most two different angles. Correspondingly, in an embodiment, a first normal N1 of the whole first end surface <NUM> or a part of the first end surface <NUM> forms a minimum angle of at most <NUM> degrees, preferably at most <NUM> degrees, most preferably at most <NUM> degrees, to a to a circumferential direction SC of the tyre at the location of the first normal N1. Thus, the first angle of inclination α' may be e.g. at least <NUM> degrees, at least <NUM> degrees, or at least <NUM> degrees, such as <NUM> degrees. Correspondingly, the third minimum angle δ may be e.g. at most <NUM> degrees; and the second main surface <NUM> of the ribbon may be quadrangular such that each angle is <NUM> to <NUM> degrees.

Referring to <FIG>, in an embodiment, a second normal N2 of the whole second end surface <NUM> forms a second minimum angle β of <NUM> to <NUM> degrees with a radial direction SR of the tyre, wherein the radial direction SR is defined at the location of the second normal N2 (i.e. at a location of the body <NUM> of the tire, the location of the body <NUM> being arranged on a same radial line as the point at which the second normal N2 is defined). Reference is made to <FIG> with the note that the curvature of the body <NUM> is highly exaggerated. Thus, in an embodiment, the second normal N2 of the whole second end surface <NUM> forms a minimum angle of least <NUM> degrees with a circumferential direction SC of the tyre at the location of the second normal N2. Thus, the second angle of inclination β' may be e.g. at most <NUM> degrees.

In an embodiment, the second minimum angle β is <NUM> to <NUM> degrees, and more preferably <NUM> to <NUM> degrees, such as <NUM> degrees. The upper limit relates to a sufficient amount of tapering in view of e.g. reducing the wear problems at the ends <NUM>, <NUM> of the ribbon, and the lower limit ensures sufficient mass balance and amount of sound-absorbing material.

The second surface normal N2 is a normal of the whole the second end surface <NUM> when the second end surface <NUM> is planar. In a preferably embodiment, the second end surface <NUM> is planar. In an embodiment, at least the part of the second end surface <NUM> is planar. However, the second end surface <NUM> needs not be planar. Thus, in an embodiment, a second normal N2 of a part of the second end surface <NUM> forms the second minimum angle β with the radial direction SR, the value of the second minimum angle β being discussed in detail above.

These values of the first minimum angle α and the second minimum angle β apply particularly when the third minimum angle δ is small in the meaning discussed above.

As for the shape of the first end surface <NUM> and the second end surface <NUM>, <FIG> show embodiment wherein the second end surface <NUM> is not planar. However, as conventional, a normal (e.g. the second normal N2 discussed above) of such a surface is definable as a normal of a tangential plane of the surface.

However, as detailed above, preferably the first angle of inclination α' is about <NUM> degrees, the second angle of inclination β' is about <NUM> degrees, and the third minimum angle δ is small (e.g. less than <NUM> degrees). How these relate to the tire, particularly the first and second minimum angles α and β was discussed above.

The preferable values for the first angle of inclination α' and the second angle of inclination β' are observable also from the ribbon <NUM> as such (i.e. in the context of method, before the ribbon <NUM> has been attached to the body <NUM> of the tyre). In an embodiment, the ribbon <NUM> comprises a first end surface <NUM> at the first end <NUM> of the ribbon <NUM> and a second end surface <NUM> at the second end <NUM> of the ribbon <NUM>.

Concerning the first angle of inclination α', in more specific terms, in an embodiment of the method the direction DI of the length Lr of the ribbon <NUM> is parallel or forms a fourth minimum angle ϕ of at most <NUM> degrees with a third normal M1, the third normal M1 being a normal of a part of the first end surface <NUM> or a normal of the whole first end surface <NUM>. The fourth minimum angle ϕ is shown in <FIG> and <FIG>. Even if not shown, clearly also in the embodiment of <FIG>, the fourth minimum angle ϕ is greater than zero. Preferably, the first end surface <NUM> is planar, and the third normal M1 is a normal of the whole first end surface <NUM>. More preferably, the direction DI of the length Lr of the ribbon <NUM> is parallel or forms the fourth minimum angle ϕ of at most <NUM>, such as at most <NUM> degrees, with the third normal M1 of a part of the first end surface <NUM> or the third normal M1 of the whole first end surface <NUM>. It is noted that both the first angle of inclination α' and the third minimum angle δ affect the fourth minimum angle ϕ defined above. Correspondingly, the third minimum angle δ may be e.g. at most <NUM> degrees; and the second main surface <NUM> of the ribbon may be quadrangular such that each angle is <NUM> to <NUM> degrees.

Concerning the second angle of inclination β', in more specific terms, in an embodiment of the method the direction DI of the length Lr of the ribbon <NUM> forms a fifth minimum angle γ of at least <NUM> degrees with a fourth normal M2 of a part of the second end surface <NUM> or the whole second end surface <NUM>. Reference is made to <FIG>. Preferably the second end surface <NUM> is planar and the fourth normal M2 is a normal of the whole second end surface <NUM>. The lower limit for the fifth minimum angle γ ensures sufficient tapering.

In an embodiment, the direction DI of the length Lr of the ribbon <NUM> forms the fifth minimum angle γ of <NUM> to <NUM> degrees, more preferably <NUM> to <NUM> degrees, with the fourth normal M2; which is a normal of a part of the second end surface <NUM> or a normal of the whole second end surface <NUM>. The upper limit for the fifth minimum angle γ ensures sufficient length of non-tapering part, which affect both sound-suppressing properties and mass balance of the tire.

As detailed above, most preferably the first angle of inclination α' is <NUM> degrees, the second angle of inclination β' is <NUM> degrees and the third minimum angle δ is zero degrees. Thereby, in that embodiment, the first minimum angle α is <NUM> degrees, the second minimum angle β is <NUM> degrees, the fourth minimum angle ϕ is zero, and the fifth minimum angle γ is <NUM> degrees.

In an embodiment a thickness Tr of the ribbon <NUM> is <NUM> to <NUM>, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>. In particular, these values of thickness apply to the non-tapering part of the ribbon <NUM>. Given that the second angle of inclination β' may be e.g. <NUM> degrees and that a radius of a tyre is typically at least <NUM> (making a circumference of the inner surface <NUM> about <NUM>), obviously a major portion of the ribbon <NUM> has a constant thickness. In an embodiment, the ribbon <NUM> has a constant thickness within an area of the second main surface <NUM>, the area being at least <NUM> % of the area of the second main surface <NUM>. The constant thickness within this area may be within the limits disclosed above for the thickness. Naturally, within the tapering part of the ribbon <NUM>, the thickness may be less, and may decrease continuously to zero.

Claim 1:
A tyre (<NUM>) comprising
- an inner surface (<NUM>) opposite an outer surface (<NUM>),
- a tread (<NUM>) forming a part of the outer surface (<NUM>), and
- a ribbon (<NUM>) comprising sound-absorbing material such that
- at least a part of the ribbon (<NUM>) is arranged opposite the tread (<NUM>),
- the ribbon (<NUM>) extends from a first end (<NUM>) of the ribbon to a second end (<NUM>) of the ribbon,
- the shape of the ribbon (<NUM>) tapers such that a thickness (Tr) of the ribbon (<NUM>) decreases towards the second end (<NUM>) of the ribbon, and
- the first end (<NUM>) of the ribbon is in contact with the second end (<NUM>) of the ribbon, wherein
- a seam (<NUM>) is arranged between the first end (<NUM>) of the ribbon (<NUM>) and the second end (<NUM>) of the ribbon (<NUM>),
- the ribbon (<NUM>) comprises a first end surface (<NUM>) at the first end (<NUM>) and a second end surface (<NUM>) at the second end (<NUM>), and
- a first normal (N1) of a part of the first end surface (<NUM>) or the whole first end surface (<NUM>) is perpendicular to a radial direction (SR) of the tyre or forms a first minimum angle (α) of at least <NUM> degrees with a radial direction (SR) of the tyre,
characterized in that
- a second normal (N2) of the part of the second end surface (<NUM>) or the second normal (N2) of the whole second end surface (<NUM>) forms a second minimum angle (β) of <NUM> to <NUM> degrees with a radial direction (SR) of the tyre,
- the seam (<NUM>) widens towards the rotational axis (AX) of the tyre (<NUM>), and
- at least a part of the second end (<NUM>) of the ribbon is compressed against the first end (<NUM>) of the ribbon.