Abstract
In a first aspect of the invention, a pneumatic tire is provided, the pneumatic tire comprising two spaced apart beads, a tread portion, a pair of sidewalls extending radially inward from axially outer edges of the tread portion to join the respective beads, the axially outer edges of the tread portion defining a tread width, a carcass, an innerliner covering the carcass and enclosing a tire cavity when mounted on a rim, and multiple layers of open cell, noise damping foam strip material attached on top of each other to the innerliner within the tire cavity in an area radially below the tread portion, wherein each layer has an axial width from 20% to 80% of the tread width and a radial thickness from 5% to 20% of the tread width and said multiple layers fill together from 8% to 40% of the volume of the tire cavity.
Claims
1. A pneumatic tire, comprising two spaced apart bead portions, a tread portion, a pair of sidewalls extending radially inward from axially outer edges of the tread portion to join the respective bead portions, the axially outer edges of the tread portion defining a tread width, a carcass, an innerliner covering the carcass and defining a tire cavity, and multiple layers of open cell noise damping foam strip material attached on top of one another to the innerliner within the tire cavity in an area radially below the tread portion, wherein each layer has an axial width from 20% to 80% of the tread width and a radial thickness from 5% to 20% of the tread width and said multiple layers fill together from 8% to 40% of the volume of the tire cavity.
2. The tire of claim 1 wherein the open cell noise damping foam strip material has a density ranging from 0.01 g/cm.sup.3 to 1 g/cm.sup.3.
3. The tire of claim 1 wherein said multiple layers are integrally formed and spirally wound on top of one another in the tire cavity.
4. The tire of claim 1 wherein a first layer of said multiple layers has a first butt splice arranged at a first circumferential position of the tire cavity, and wherein a second layer of said multiple layers has a second butt splice arranged at a second circumferential position of the tire cavity which is different from the first circumferential position.
5. The tire of claim 4 wherein the position of the second butt splice of the second layer is arranged at an angular position which is between 100° and 260° circumferentially shifted from an angular position of the first butt splice of the first layer.
6. The tire of claim 1 wherein the layers have one or more of: an axial width ranging from 50% to 70% of the tread width, a radial thickness ranging from 5% to 15% of the tread width, and fill together from 20% to 40% of the volume of the tire cavity.
7. The tire of claim 1 wherein each of the layers is arranged essentially in parallel to the equatorial plane of the tire and has a length covering at least 80% of the inner circumference of the tire.
8. The tire of claim 1 wherein a first foam strip material layer attached to the innerliner has a smaller axial width than a second foam strip material layer arranged on top of the first foam strip material layer attached to the inner liner.
9. The tire of claim 1 wherein at least two of said layers are mechanically interlocked to one another along their length.
10. The tire of claim 9 wherein said interlocking is essentially continuous over the length of the foam strip material between two layers attached on top of each other.
11. The tire of claim 9 wherein said layers are mechanically interlocked by a member selected from the group consisting of one or more dove tail connections, one or more jigsaw connections, hook-and-loop fasteners, plastic rivets, and plastic screws.
12. The tire of claim 1 wherein at least one of the layers has a butt splice mechanically interlocked at its meeting face sides.
13. The tire of claim 1 wherein the layers are interconnected to one another by at least one of: glue, hook-and-loop fastener tape, adhesive tape, double-sided adhesive tape, plastic rivets, and plastic screws.
14. The tire of claim 1 wherein a radially outermost foam strip material layer is attached to the innerliner by at least one of a sealant material and an adhesive.
15. The tire of claim 1 wherein at least one of the layers is coated with metal.
16. The tire of claim 1 wherein at least two layers have the same radial thickness and/or the same radial width.
17. The tire of claim 1 wherein at least two layers are comprised of the same foam strip material.
18. The tire of claim 1 wherein the tire is a passenger car tire.
19. The tire of claim 1 wherein the tire is a bus tire for a rim size of 22.5 inch.
20. The tire of claim 1 wherein the open cell noise dampening foam strip material is comprised a material selected from the group consisting of polyurethane foam, polyethylene foam, and foam rubber.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The structure, operation and advantages of the invention will become more apparent upon contemplation of the following description taken in conjunction with the accompanying drawings, wherein:
[0043] FIG. 1 shows a schematic cross-section of a truck or bus tire having two layers of foam material in accordance with an embodiment of the present invention.
[0044] FIG. 2 shows a schematic cross-section of another truck or bus tire having two layers of foam material with different axial width in accordance with another embodiment of the present invention.
[0045] FIG. 3 shows a schematic cross-section of another truck or bus tire having four layers of foam material connected along the strip length by dove tail connections and bound to the innerliner of the tire by a sealant layer, all in accordance with yet another embodiment of the present invention.
[0046] FIG. 4 shows a schematic cross-section of yet another truck or bus tire in accordance with yet another embodiment of the present invention and having three layers of foam material connected along the strip length by dove tail connections with a male end of the first layer glued to the innerliner of the tire.
[0047] FIG. 5 shows a schematic cross-section in parallel to the equatorial plane of the tire showing two layers of open cell noise damping foam strip material, wherein each layer has a butt splice (the tire as such is not shown in this Figure).
[0048] FIG. 6 shows a schematic cross-section in parallel to the equatorial plane of the tire showing two spirally wound layers of open cell noise damping foam strip material, wherein each layer has a butt splice (the tire as such is not shown in this Figure).
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0049] FIG. 1 is a schematic cross-section of a bus or truck tire 1. The tire 1 has a tread 10, an inner liner 13, a belt structure comprising a plurality of belt plies 12, a carcass ply 9, two sidewalls 2, and two bead regions 3 comprising bead filler apexes 5 and beads 4. The carcass ply 9 includes a pair of axially opposite end portions 6, each of which is associated with a respective one of the beads 4. Each axial end portion 6 of the carcass ply 9 may be turned up and around the respective bead 4 to a position to anchor each axial end portion 6. The turned-up portions 6 of the carcass ply 9 may engage the axial outer surfaces of two flippers 8 and axial inner surfaces of two chippers 7. As shown in FIG. 1, the example tread 10 may have four circumferential grooves 20, each groove essentially defining a U-shaped opening in the tread 10. In accordance with a first embodiment of the invention, the tire 1 comprises two (stacked) layers 30 of a noise damping foam strip material. They are attached to the radially inner side of the innerliner 13, preferably by means of a glue such as Loctite® from Henkel, for instance the 5900 series including 5900, 5910 and 5970. Both layers 30 are essentially arranged in the circumferential direction in parallel to the equatorial plane EP of the tire 1. The radial direction r, the circumferential direction c and the axial direction a have been indicated for the sake for easier reference. It is noted however, that the depicted orientations of the axial direction a and the circumferential direction c shall not be limiting the invention. The volume covered by the two layers 20 shall be in accordance with the invention at least 8% (preferably 15%) of the tire cavity volume but less than 40% of the latter. The volume of the tire cavity shall be understood as the volume enclosed by the innerliner of the tire (especially in an unmounted and uninflated state) and closed by an (imaginary) circumferential ring-shaped plane contacting the radially innermost edges of both bead portions 3. That plane is schematically shown in FIG. 1 by a dashed line connecting the radially innermost edges of the tire 1.
[0050] As shown in FIG. 5, each layer of multiple layers may be wound in the circumferential direction, wherein each layer 30 may have a butt splice 31. Preferably, butt splices of different layers 30 are not provided at same angular positions but are for instance mounted opposite to each other as shown in FIG. 5 (shifted by 180° with respect to the circumferential direction). For the sake of clarity, the tire 1 as such is not shown in FIG. 5. The axial direction a is indicated in the center of the circumferentially arranged layers 30.
[0051] Alternatively, and as depicted in FIG. 6, multiple layers 30′ could be spirally wound on top of each other. This limits the number of splices and simplifies mounting. As in other embodiments, multiple layers 30′ may for instance be glued to one another. Alternatively, other means may be used such as adhesive tapes or for instance Velcro connections. Further options are described in the context of other embodiments.
[0052] While the embodiment of FIG. 1 suggests a plurality of tire components including for instance apexes 5, chippers 7 and flippers 8, such components are not mandatory for the invention. Also, the turned-up end of the carcass ply 9 is not necessary for the invention or may pass on the opposite side of the bead area 3 and end on the axially inner side of the bead 4 instead of the axially outer side of the bead 4. The tire 1 could also have for instance more or less than four grooves or a different number of belt plies than depicted.
[0053] FIG. 2 shows another example of a tire 101 which has multiple layers 103, 103′ of open cell noise dampening foam strip material. For the sake of easier reference, the same reference numerals as in FIG. 1 have been used for other elements of the tire 101. The same applies to FIGS. 3 and 4 respectively. In contrast to the embodiment of FIG. 1, FIG. 2 shows a first layer 103 of open cell noise dampening foam strip material which has a first axial width and a second layer 103′ which has a second, larger axial width than the first layer 103. This arrangement may help to improve cooling of the tire in an area below the tread 10. This effect may be further improved by providing an open cell noise dampening foam strip material with lower density in layer 103 than in layer 103′. Thus, layer 103′ may have better noise dampening properties than layer 103 while allowing a better cooling of the tread area than in the arrangement shown in FIG. 1.
[0054] FIG. 3 shows yet another embodiment in accordance with the invention in which a tire 110 has four layers 130 of open cell noise dampening foam strip material. A first layer 130 is attached to the innerliner 13 by means of a sealant layer 11. Thus, the sealant layer 11 acts as adhesive. Sealants are typically used to seal punctures in the tread 10, as for instance by screws or nails. Such sealant material is typically very sticky and known to the person skilled in the art. Instead of gluing multiple layers 130 to one another, layers 130 are connected to each other by dove tail connections. In particular, each layer 130 has on one side a male element and on its opposite side a female element for mechanically interconnecting or fitting layers between each other. Preferably, such interconnecting elements are provided in a center area of the layers 130. This modular system allows easy adding of layers in dependence of the actual tire. Glues are avoided completely in this embodiment.
[0055] FIG. 4 shows another embodiment in accordance with the present invention in which a tire 111 has three layers 133 mechanically interconnected again by dove tail connectors. In this embodiment, the male dove tale connector element of a first layer 133 is glued to the innerliner 13 of the tire. This configuration has the advantage that the male element has a smaller axial width than the whole axial width of the first layer 133 and creates a distance between the majority of the surface of the layer 133 facing the innerliner 13 below the tread. Thereby, a slot is created between the first layer 133 and the inner liner 13 which improves the cooling properties of the shown example. Said first layer 133 has a female dove tail connector element on a side of the layer 133 opposite to the side on which the male connector is arranged. In other words, the female connector is provided on a radially inner side of the layer 133, whereas the male connector is provided on a radially outer side of the layer 133. The same may apply respectively for one or more further layers attached to the first layer 133.
[0056] Variations in the present invention are possible in light of the provided description. While certain representative embodiments, examples 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 invention. It is, therefore, to be understood that changes may be made in the particular example embodiments described which will be within scope of the invention as defined by the following appended claims. In any case the above described embodiments and examples shall not be understood in a limiting sense. In particular, the features of the above embodiments may also be replaced or combined with one another.
